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Program for HOPV17

21st May 2017 - Day 0 (Sunday)
16.30 - 17.30 Registration
17.30 - 18.30 Welcome reception
22nd May 2017 - Day 1 (Monday)
General session G1
8.45 - 9.00 Opening
Chair: Anders Hagfeldt
9.00 - 9.45 G1.K1 Park, Nam-Gyu
Sungkyunkwan University

Organic-Inorganic Halide Perovskites: From PV to ReRAM

Nam-Gyu Park*

Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon, 440, KR

Since the first report on solid-state perovskite solar cell with power conversion efficiency (PCE) of 9.7% in 2012, intensive researches led to its PCE upto 22%. It is believed that perovskite solar cell is promising next-generation photovoltaics (PVs) thanks to superb performance and very low cost. Besides photovoltaics, halide perovskite exhibits multifunctional properties. In this talk, methodologies for high PCE perovskite solar cell will be given in terms of grain size control and grain boundary engineering. Grain boundary is found to play important role in charge transporting, where charge conduction is pronounced for the perovskite film prepared from grain boundary healing process. Stability and I-V hysteresis are now critical issues in perovskite solar cell. Light-soaking and temperature-dependent test results will be discussed to understand photo- and thermal-stability of perovskite solar cells. Nonstoichiometric approaches extend to light emitting diode application, where we discovered highly efficient green light emitting materials and devices. Extremely sensitive X-ray imaging system was developed based on halide perovskite, which is highly beneficial for low radiation doses for medical examinations such as mammography and even computed tomography. Halide perovskite enables nonvolatile resistive random access memory (ReRAM) device with extremely high on-off ratio and millivolt switching, which will be discussed in detail.

9.45 - 10.15 G1.I1 De Angelis, Filippo
ISTM-CNR Perugia

Light-induced processes in organohalide perovskites: Defects and polarons

Filippo De Angelis*

a, ISTM-CNR Perugia, Via Elce di Sotto 8, Perugia, 6123, IT
b, 3CompuNet, Istituto Italiano di Tecnologia, , Via Morego 30, 16163 Genova, Italy, IT

We illustrate the results of ab initio molecular dynamics simulations coupled to first principles electronic structure calculations on the effect of light absorption on the electronic and dynamical properties of organohalide lead perovskites. The role of the organic cation dynamics and of ion/defect migration is analyzed in relation to photoinduced structural transformations and solar cell operation. Iodine defects, such as vacancies and interstitials, undergo a light-induced dynamical transformation leading to their mutual annihilation, accounting for the observed enhanced photoluminescence quantum yield following light irradiation. We also show how most of perovskites unusual properties in terms of defects and trapping dynamics can be explained by the close similarity between the perovskite properties and the photochemistry of iodine, both for 3D and 2D materials. Along with the unusual defect chemistry, the role of large polarons in screening charge carriers from recombination is finally illustrated based on quantitative models that allow us to estimate the extent and size of polaron distortion in various perovskites from first principles. The combination of unusual defect chemistry and of polaron screening of the charge carriers largely contributes to the outstanding optoelectronic properties of organohalide perovskites materials.   


J.M. Azpiroz et al. Energy Env. Sci. 2015, 8, 2118.

C. Quarti et al. Energy Env. Sci. 2016, 9, 155.

E. Mosconi et al. ACS Energy Lett. 2016, 1, 182.

E. Mosconi et al. Energy Environ. Sci. 2016, 9, 3180.

D. Cortecchia et al. J. Am. Chem. Soc. 2017, 139, 39.

K. Domansk et al.  Energy Environ. Sci. 2017, DOI: 10.1039/C6EE03352K.

J. Bisquert et al. ACS Energy Lett. 2017, 2, 520.

10.15 - 10.45 G1.I2 Stingelin, Natalie
Imperial College London

Organic Photovoltaics: Challenges and Opportunities

Natalie Stingelin*

a, Imperial College London, Department of Materials, Exhibition Road, London, 0, GB
b, Georgia Institute of Technology, Materials Science, USA

In the past decade, significant progress has been made in the fabrication of organic photovoltaic devices (OPVs), predominantly due to important improvements of existing materials and the creation of a wealth of novel compounds. Many challenges, however, still exist. Real understanding of what structural and electronic features determine, for instance, the short-circuit current (Jsc), open-circuit voltage (Voc) and fill factor are still lacking; and the role of charge transfer states and which charge transfer states are critical for efficient charge generation are still debated. Here we attempt to obtain further insight of relevant structure/processing/performance interrelations using classical polymer processing ‘tools’. We present a survey on the principles of structure development of this material family and how it can be manipulated, with focus on how to control the phase morphology and important interfaces (molecular and between different phase regions). Goal is to tailor and tune the final ‘morphology’ towards establishing correlations with relevant device characteristics. We will discuss interrelations of the presence of intermixed phases with charge transfer absorption, how we can manipulate the charge transfer energy and what structural features seem to influence Voc. In addition, examples are given how device performances can be further increased, e.g., by use of light/heat management structures and use of anti-reflection coatings.

10.45 - 11.15 Coffee Break
Chair: Anders Hagfeldt
11.15 - 11.45 G1.I3 Hayase, Shuzi
Kyushu Institute of Technology

Enhancement of efficiency for mixed metal Sn/Pb perovskite solar cells-What lowers efficiency-

Yuhei Ogomia, Kengo Hamadaa, Daisuke Hirotania, Ayumu Yonahaa, Erina Yamaguchia, Shen Qingb, Taro Toyodab, Kenji Yoshinoc, Takashi Minemotod, Ripolles Teresaa, Shuzi Hayase*a

a, Kyushu Institute of Technology , 204 Hibikino Wakamatsu-ku, Kitakyushu - Fukuoka, 808, JP
b, The University of Electro-communications, 1-5-1 Chofugaoka, Choufu, 18208585, JP
c, Miyazaki University, 1-1, Gakuennkonohanadainishi, Miyazaki, 889-2192, JP
d, Ritsumeikan Universitry, 1-1, Tourohigashi, Kusatsushi, 525-8577, JP

The efficiency of the perovskite solar cells consisting of Pb has been reported to be over 20%.  Absorption edge of perovskite (PVK) solar cells consisting of MAPbI3 is 800nm (Band gap: 1.55eV) which limiting the enhancement of the efficiency from the view point of Jsc. According to our simulation, light harvesting in the area of near IR up to 900nm (band gap:1.38eV) is necessary for enhancing the efficiency. This prompted us to develop new solar cells having photoconversion properties in longer wavelength region. We have already reported that mixed metal perovskite (MAPbxSnyI3) showed photoconversion properties in IR region (up to 1000 nm) (1-2).  The short circuit current (Jsc) was high, reaching to 30 mA/cm2 (for comparison, 24mA/cm2 for MAPbI3) because of the wide range of light harvesting properties from visible to IR regions.  However, the open-circuit voltage (Voc) was lower than 0.3 V and the voltage loss expected from the band gap was 0.6-0.7 V, which was much larger than that of MAPbI3 (0.4 V), suggesting the presence of high density charge recombination centers. We discuss why the perovskite solar cells consisting of Sn have low efficiency, compared to MAPbI3 from the view point of hetero-interface architecture. We found that Ti-O-Sn bonds formed at the interface between Tiania and MAPbxSnyI3 layer by using Quartz Crystal Microbalance systems (QCM) and XPS analysis.  Surprisingly, under the presence of Ti-O-Sn linkages, at -4.2 eV from the vacuum level, the trap density of the interface increased from 1013/cm3 to 1014/cm3, implying that Ti-O-Sn at the TiO2/perovskite interface creates new traps, resulting in increasing opportunities of charge recombination at the interfaces. Actually, drastic decrease in the efficiency of solar cells (MAPbI3) was observed when Ti-O-Sn linkages were inserted in the interface between TiO2 and MAPbI3 layer for the MAPbI3 solar cells.  After removing the Ti-O-Sn bond, the efficiency drastically increased from 4.0 % to 13.8 % and the stability was improved. Voc loss was reduced to 0.4-0.5 V, which became close to that for MAPbI3. It was proved that interface architecture is quite important for enhancing the MAPbxSnyI3 solar cells.

References1. S. Nakabayashi, et al., J. Photonics for Energy; 2015, 5, 057410. 2. Y. Ogomi, et al., J. Phys. Chem. Lett. 2014, 5, 1004-1011.

11.45 - 12.15 G1.I4 Segawa, Hiroshi
The University of Tokyo

Basics and Applications of Organometal Halide Perovskite Solar Cells

Hiroshi Segawa*

a, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo, 1538904, JP
b, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo, 1538902, JP

Next-generation solar cells based on new concepts and/or novel materials are currently attracting wide interests.Among them, organometal halide perovskite solar cells (PSC) based on CH3NH3PbI3 have attracted attention in the last few years due to their outstanding performance as photovoltaics. Despite the unique properties and higher efficiencies of PSCs, several important issues still remained, e.g., mysterious hysteresis in I-V curves and dispersion of the performances. It has been found the hysteresis strongly depends on the device architecture, where the planar PSCs show relatively large hysteresis than meso-structured PSCs. In this study, we found that an equivalent circuit model with a series of double diodes, capacitors, shunt resistances, and single series resistance produces simulated I-V curves with large hysteresis matching with the experimentally observed curves. On the other hand, we found that the inhomogeneous photo-physical properties of the organometal halide perovskite. In order to improve the energy conversion efficiency, we should control the properties. Additionally, we have prepared the various tandem solar cells with spectral splitting system showing a high overall power conversion efficiency.

12.15 - 12.45 G1.I5 Boschloo, Gerrit
Uppsala University, Dept. Chemistry Ångström Laboratory

Pyridine-Mediated Recrystallization of CH3NH3PbI3 leading to Improved Perovskite Solar Cells

Sagar Jaina, Tomas Edvinssonb, Gerrit Boschloo*a

a, Uppsala University, Dept. Chemistry Ångström Laboratory, Box 523, Uppsala, 75120, Sweden
b, Uppsala University, Dept. Engineering Sciences, Box 534, Uppsala, 751 21, Sweden

Films of the hybrid lead halide perovskite CH3NH3PbI3 were found to react with pyridine vapor at room temperature, leading to complete bleaching of the film. In dry air or nitrogen atmosphere recrystallization takes place, leading to perovskite films with markedly improved optical and photovoltaic properties. The physical and chemical origin of the reversible bleaching and recrystallization mechanism was investigated using a variety of experimental techniques and quantum chemical calculations. The strong Lewis base pyridine attacks the CH3NH3PbI3. The mechanism can be understood from a frustrated Lewis pair formation with a partial electron donation of the lone-pair on nitrogen together with competitive bonding to other species as revealed by Raman spectroscopy and DFT calculations. The bleached phase consists of methylammonium iodide crystals and an amorphous phase of PbI2(pyridine)2. After spontaneous recrystallization the CH3NH3PbI3 thin films have remarkably improved photoluminescence and solar cell performance increased from 9.5 % for as-deposited films to more than 18 % power conversion efficiency with negligible hysteresis conversion efficiency under AM1.5G illumination for recrystallized films for solar cells with planar geometry (FTO / compact TiO2 / CH3NH3PbI3 / spiro-MeOTAD / Au). Hysteresis was negligible and open-circuit potential was remarkably high, 1.15 V. The results show that complete recrystallization can be achieved with a simple room temperature pyridine vapor treatment of CH3NH3PbI3 films leading to high quality crystallinity films with drastically improved photovoltaic performance.

12.45 - 13.00 Sponsor talk: TCI Europe
13.00 - 14.30 Lunch
Session A1
Chair: Michael McGehee
14.30 - 15.00 A1.IS1 Unger, Eva L.
Division of Chemical Physics, Department of Chemistry

Recent Trends in Tuning the Band Gap of Metal-Halide Perovskites

Eva L. Unger*a, b, Steve Albrechtc, Bernd Rechd

a, Division of Chemical Physics, Department of Chemistry, Lund University, Sweden
b, Young Investigator Group Hybrid Materials Formation and Scaling, , Germany
c, Young Investigator Group Perovskite Tandem Solar Cells, , Germany
d, Institute for Silicon Photovoltaics, Helmholtz-Zentrum Berlin fr Materialien und Energie, Germany

Metal halide perovskite semiconductors might have their most important purpose for the development of large area low-cost hybrid tandem photovoltaics. One prerequisite to achieve this goal is the tunability of the semiconductor band gap, which can be feasibly achieved through chemical engineering in ABX3 alloys. Tremendous progress has been made in this field of research and many valuable data sets for a great variety of ABX3 alloys provided that we recently reviewed to highlight the progress of perovskite photovoltaics in general and reflect on the potential of higher as well as lower band gap materials for hybrid tandem devices. This overview allowed us to fully appreciate the limitations to the band gap tunability of higher band gap metal halide perovskites imposed by photo-induced phase segregation phenomena in mixed bromide/iodide alloys that seem to occur quite independently of the particular preparation methods of sample series investigated in various different data sets. This phenomena was first described by Hoke et al. and limits the open circuit voltage and hence power conversion efficiency of mixed bromide/iodide compounds with band gaps larger than 1.7 eV. In regard to hybrid tandem device technology based on bottom absorber materials such as silicon or CIGS, photostable higher band gap metal-halide perovskite materials are available that will enable the realization of high efficiency hybrid tandem device technology with efficiencies approaching 30% power conversion efficiencies

15.00 - 15.15 A1.O1 McMeekin, David
Clarendon Laboratory, University of Oxford

Crystallization kinetics and morphology control of mixed-cation lead mixed-halide perovskite via tunability of the colloidal precursor solution

David McMeekina, Zhiping Wanga, Waqaas Rehmana, Federico Pulvirentib, Jay Patela, Nakita Noela, Michael Johnstona, Seth Marderb, Laura Herza, Henry Snaith*a

a, Clarendon Laboratory, University of Oxford, Robert Hooke Building, Parks Road, Oxford, 0, GB
b, School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332-0400, US

The meteoric rise of the perovskite solar cell field has been fueled by the ease with which a wide range of high-quality materials can be fabricated via simple solution processing methods. However, to date, little effort has been devoted to understanding the precursor solutions, and the role of additives such as hydrohalic acids upon film crystallization and final optoelectronic quality. In this work, we establish a direct link between the colloids concentration present in the [HC(NH2)2]0.83Cs0.17Pb(I0.8Br0.2)3 precursor solution and the nucleation and growth stages of the thin film formation. Using dynamic light scattering analysis, we monitor the dissolution of colloids over a time span triggered by the addition of hydrohalic acids. These lead polyhalide colloids appear to provide nucleation sites for the perovskite crystallization, which critically impacts morphology, crystal quality, and optoelectronic properties. Via two-dimensional X-ray diffraction we observe highly ordered and textured crystals for films prepared from solutions with lower colloidal concentrations. This increase in perovskite crystal quality allows for a significant reduction in microstrain along with a twofold increase in charge-carrier mobilities leading to values exceeding 20cm2V-1s-1. Using a solution with an optimized colloidal concentration, we fabricated devices that reach current-voltage measured power conversion efficiency of 18.8%, and stabilized efficiency of 17.9%.

15.15 - 15.30 A1.O2 Galisteo-López, Juan F.
Instituto de Ciencia de Materiales de Sevilla (ICMS-CSIC)

3D Optical Tomography and Correlated Elemental Analysis of Hybrid Perovskite Microstructures

Juan F. Galisteo-López*a, Yuelong Lib, Hernán Míguez*a

a, Instituto de Ciencia de Materiales de Sevilla (ICMS-CSIC) , C/ Américo Vespucio 49, Seville, 41092, ES
b, Nankai University, 94 Weijin Road, Nankai District, Tianjin 300071, CN

Hybrid organic inorganic perovskites have shown a great potential for optoelectronic applications over the past few years. The interest in these materials was originally triggered by studies of methyl ammonium lead iodide (MAPbI3) leading to photovoltaic devices presenting unprecedented efficiencies for a solution processed material. In parallel with the outstanding properties from the point of view of light harvesters came evidences of an excellent performance as light emitter paving the way for its use in light emitting applications. [1]

Recent studies have focused on two technologically relevant applications from the point of view of light emitters: light emitting diodes and lasers. In the latter approach the perovskite can be used as a gain material to be incorporated into an optical cavity following the conventional lasing approach or, due to the possibility of crystallizing these structures into polygonal shapes, use nano and microstructures as lasing resonators themselves profiting from the feedback provided by internal reflections. The use of microstructures is particularly appealing from the point of view of developing components for micro and nanoscale photonic and optoelectronic devices. Whether its use is intended as active elements for LEDs or coherently emitting lasers a precise knowledge of the emissive properties of the micro structure is essential.

Herein we propose the use of correlated optical (laser scanning confocal microscopy - LSCM) and structural (scanning electron microscopy - SEM) characterization together with elemental information (provided by energy dispersive spectroscopy - EDS) as a tool to evaluate the viability of hybrid organic inorganic based perovskite micro structures for light emitting purposes. [2] In particular we concentrate on methyl ammonium lead bromide (MAPbBr3) structures which have demonstrated the most efficient emission in the visible leading to lasing. This combined approach provides a bulk spatially and spectrally resolved map of the PL of these structures which reflects its homogeneity and allows tackling certain fundamental aspects of the emission of these structures such as the role of light-induced ion migration in their optical properties. Further the structural and optical implications of light induced material degradation, a fundamental issue for this material as many applications will demand external illumination, are discussed evidencing the role of the migration of the halide component in this type of materials.

[1] Y-H.Kim, H. Cho and T-W. Lee, Proc. Natl. Acad. Sci. U. S. A. 2016, 113, 11694–11702.

[2] J.F. Galisteo-López, Y. Li and H. Míguez, J. Phys. Chem. Lett. 2016, 7, 5227-5234.

15.30 - 15.45 A1.O3 Barolo, Claudia
Department of Chemistry, NIS Interdepartmental Centre and INSTM Reference Centre, Università degli Studi di Torino

Quasi-solid Aqueous Electrolytes based on bio-derived polymers

Simone Gallianoa, Federico Bella*b, Marisa Falcob, Giovanni Proveraa, Claudia Barolo*a, Fabrizio Giordanoc, Gerrit Boschlood, Michael Graetzelc, Anders Hagfeldtc, Claudio Gerbaldib, Guido Viscardia

a, Department of Chemistry, NIS Interdepartmental Centre and INSTM Reference Centre, Università degli Studi di Torino, Via Pietro Giuria 7, TORINO, 10125, IT
b, GAME Lab, CHENERGY Group, Department of Applied Science and Technology (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 - Torino, Italy, IT
c, Laboratory of Photonics and Interfaces, Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH1015 Lausanne, Switzerland, CH
d, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry, Uppsala University, Box 523 SE 75120 Uppsala Sweden, SE

In recent years, with the idea of creating efficient, safe, and low-cost DSSCs, the research moved the attention towards alternative solvent-based electrolytes. Above all, DSSCs with water-based electrolytes have been proposed as one of the possible solution providing reduced costs, non-flammability and environmental compatibility.[1] Recently we demonstrated that stability issues can be properly addressed by choosing the appropriate dye.[2] Moreover, the possibility of gelling the liquid solvent into a polymeric matrix can reduce the electrolyte leakage outside the device, increasing the long-term stability.

In this contribution, the investigation on a series of iodine and cobalt-based 100% aqueous electrolytes is presented. Thanks to our previous experience [3] and to a multivariate approach (Design of Experiment), the effects of the change in redox mediator concentrations and in photoanode preparation on DSSCs performances have been evaluated. Finally, the gelation of the best aqueous electrolytes with bio-derived polymers has been performed.[4] Photovoltaic performances and stabilities will be discussed by comparing liquid and gel electrolytes. In lab-scale solar cells interesting photovoltaic performances superior to 4% were achieved.



 [1] F. Bella, C. Gerbaldi, C. Barolo and M. Grätzel, Chem. Soc. Rev. 44 (2015) 3431-3473.

[2] S. Galliano, F. Bella, C. Gerbaldi, M. Falco, G. Viscardi, M. Grätzel and C. Barolo, Energy Technol. (2016) DOI:10.1002/ente.201600285.

[3] F. Bella, S. Galliano, M. Falco, G. Viscardi, C. Barolo, M. Grätzel and C. Gerbaldi, Chem. Sci. 7 (2016) 4880-4890.

[4] F. Bella, S. Galliano, M. Falco, G. Viscardi, C. Barolo, M. Grätzel and C. Gerbaldi, Green Chem., DOI: 10.1039/C6GC02625G.


15.45 - 16.00 A1.O4 Molina-Ontoria, Agustin

Tailoring Hole-transporting Materials Based on Benzotrithiophene for Perovskites Solar Cells: Isomerism effect on the photovoltaic properties

Agustin Molina-Ontoria*a, Iwan Zimmermannb, Javier Urieta-Morac, Ines García-Benitoc, Juan Aragód, Enrique Ortí*d, Mohammad Khaja Nazeeruddin*b, Nazario Martin*c

a, IMDEA , C/faraday, 9, Madrid, 28049, Spain
b, Ecole Polytechnique Fédérale de Lausanne, Sion, 1951, Switzerland, Switzerland
c, Department of Organic Chemistry, Faculty of Chemistry, University Complutense, E-28040 Madrid, Spain
d, Instituto de Ciencia Molecular, Universidad de Valencia, Catedrático José Beltrán 2, 46980 Paterna, Spain

Since the advent of organic–inorganic hybrid methylammonium (MA) lead halide MAPbX3 perovskites as active materials for photovoltaic applications in 2009, [1] the PCE of perovskite-based solar cells (PSCs) has dramatically increased from the initial 3.8% to a recently certified 22.1%. [2] Emerging from this groundbreaking discovery, an unprecedented scientific research has sprouted in the field of photovoltaics due to their exceptional physical properties. Therefore, the development of cost-effective HTMs with high efficiency along with a good stability is an important task to address.Planar and sulfur-rich polycyclic aromatic hydrocarbons bearing arylamine moieties have demonstrated to be a successful approach for designing new highly efficient HTMs for PSCs. [3] Conventionally, the π-extended conjugation associated with the planar and electron-rich structure of the fused heterocycles enable them to show strong stacking through intermolecular interactions (π‒π, S···S), thereby bestowing enhanced hole-carrier mobilities. This behaviour is beatifully exemplified by anthra[1,2-b:4,3-b′:5,6-b′′:8,7-b′′′]tetrathiophene-based (ATT) HTMs. [4] Here we report a readily available new class of multi-armed, sulfur-rich hole transporting materials based on pi-conjugated central cores. Devices were fabricated using state-of-the-art mixed anion mixed halide perovskite composition with the nominal formula [FAPbI3]0.85[MAPbBr3]0.15 (FA = formamidinium, MA = methylammonium). The performance of the solar cells employing the novel HTMs were measured under simulated 1 sun irradiation and conversion efficiencies of up to 19 % were obtained. 

References [1]    Kojima A., Teshima K., Shirai Y. and Miyasaka T., “Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells”,J. Am. Chem. Soc., 131, 17, (2009), pp 6050-6051.[2]    National Renewable Energy Laboratory, N.R.E.L.[3]    Molina-Ontoria A., Zimmermann I., Garcia-Benito I., Gratia P, Roldán-Carmona C., Aghazada S., Graetzel M., Nazeeruddin M.K., and Martín, “Benzotrithiophene-Based Hole-Transporting Materials for 18.2 % Perovskite Solar Cells”, Angew. Chem. Int. Ed., 55, 21, (2016), pp 6270-6274.[4]    Zimmermann I, Urieta-Mora J., Gratia P., Aragó J., Grancini G., Molina-Ontoria A., Ortí E., Martín N. and Nazeeruddin M. K., “High-Efficiency Perovskite Solar Cells Using Molecularly Engineered, Thiophene-Rich, Hole-Transporting Materials: Influence of Alkyl Chain Length on Power Conversion Efficiency”, Adv. Energy Mater., (2016), DOI: 10.1002/aenm.201601674.

16.00 - 16.30 Coffee break
Chair: Michael McGehee
16.30 - 16.45 A1.O5 Urano, Toshiyuki
Chemical materials evaluation and research base(CEREBA)

Evaluation of flexible organic and hybrid perovskite photovoltaic device stability

Toshiyuki Urano*a, Akira Suzukia, Hideo Yamagishia, Hiroshi Tomiyasua

Chemical materials evaluation and research base(CEREBA), 1-1-1 Higashi AIST 5-2, Tsukuba, 305-8565, Japan

The Chemical Materials Evaluation and Research Base (CEREBA) was founded in 2011 as a common R&D base for the Japanese chemical industry with the purpose to accelerate commercialization of new chemical materials for organic electronic devices. Also, since October 2013, CEREBA is conducting additional projects aimed at the developing novel materials and evaluation methods for flexible perovskite solar cells (Flex-PVS SC). Precise determination of water vapor and oxygen transmission rates (WVTR and OTR) are of considerable importance for the optimization of shelf life and production cost of encapsulated Flex-PVS SC devices. Several evaluation methods for WVTR in the range of 10-3 g/m2/day were already reported by using reference films with different orifice size as barrier film standards [1]. However, the reliable evaluation of WVTR below 10-3 g/m2/day is a well-known problem, because different measurement methods [2,3] yield different WVTR values with discrepancies greater than one order of magnitude. In this report, we present our progress on development of reliable WVTR evaluation methods as well as on development of Flex-PVS SCs [4] fabricated by low-temperature process and encapsulated by high-quality barrier films [5]. We have successfully developed an original approach to the reliable evaluation of WVTR, which is accurate down to the 10-6 g/m2/day level. We have used highly precise orifices fabricated by electroplating method in an aluminum foil attached to a 100 μm thick PET film with the orifice opening areas (S) in the range of 10-6-10-4 m2 corresponding to WVTR of 10-6 - 10-1 g/m2/day. We have compared WVTR of the films with single and multiple pinholes and obtained a good linear relationship between WVTR and S in both cases, even by different evaluation methods such as atmospheric pressure ionization mass spectrometry, cavity ring-down spectroscopy and differential pressure system method. We have also demonstrated fabrication of Flex-PVS SC with PCE of 8% encapsulated by the barrier film with WVTR of 10-2 g/m2/day. In the next research stage, we plan to apply the OTR evaluation methods that we previously developed for our OLED R2R technology in order to evaluate stability of the Flex-PVS SCs depending on OTR properties of the barrier film.


[1] T. Urano, HOPV15, 345 (2015).

[2] P. E. Burrows et. al., Displays 22, 65 (2001).

[3] S. Hara, A. Suzuki, H. Takahagi, Proc. International Display Workshop (2013).

[4] Japanese Patent 2015-103389.

[5] Japanese Patent 2015-177454.

16.45 - 17.00 A1.O6 Luo, Jingshan
Laboratory of Photonics and Interfaces

Perovskite Solar Cells for the Generation of Fuels from Sunlight

Jingshan Luo*a, Matthew T. Mayera, Marcel Schreiera, Michael Grätzela

Laboratory of Photonics and Interfaces, École Polytechnique Fédérale de Lausanne, Lausanne, CH-1015, Switzerland

Fossil fuels are finite energy resources, and their burning causes air pollution and emits large amount of CO2 leading to global warming. Inspired by natural photosynthesis, converting solar energy directly into chemical fuels through water splitting and CO2 reduction is considered as a promising strategy to fulfill human’s energy demand in a green and sustainable way, and in the meantime solves the solar intermittency issue for photovoltaics. Splitting water requires an applied voltage of at least 1.23 V to provide the thermodynamic driving force. Because of the practical overpotentials associated with reaction kinetics, a substantially larger voltage is generally required, and the overpotential to drive CO2 reduction is even larger. This complicates conventional solar cells—such as Si, thin-film copper indium gallium selenide (CIGS), and cadmium telluride (CdTe)—because of their incompatibly low photovoltage.1 The emergence of perovskite solar cells provides new opportunities, mainly due to their high photovoltage and bandgap tunability.2 They can either serve as a bias source for photovoltaic-photoelectrochemical tandem water splitting devices or take the lead in photovoltaic electrolysis approach by connecting in series.3,4 In this talk, we will provide an overview of our recent demonstrations of solar fuel generation with perovskite solar cells.1-6  


1. J Luo, JH Im, MT Mayer, M Schreier, MK Nazeeruddin, NG Park, SD Tilley, HJ Fan, M Grätzel, Science, 2014, 345, 1593-15962.

2. J Luo, MT Mayer, M Grätzel, Organic-Inorganic Halide Perovskite Photovoltaics, 2016,285-305.

3. J Luo, Z Li, S Nishiwaki, M Schreier, MT Mayer, P Cendula, YH Lee, K Fu, A Cao, MK Nazeeruddin, YE Romanyuk, S Buecheler, SD Tilley, LH Wong, AN Tiwari, M Grätzel, Adv. Energy Mater., 2015, 5, 1501520.

4. J Luo, DA Vermaas, D Bi, A Hagfeldt, WA Smith, M Grätzel, Adv. Energy Mater., 2016, 6, 160010. 

5. P Dias, M Schreier, SD Tilley, J Luo, J Azevedo, L Andrade, D Bi, A Hagfeldt, A Mendes, M Grätzel, MT Mayer, Adv. Energy Mater., 2015,5, 1501537.

6. M Schreier, L Curvat, F Giordano, L Steier, A Abate, SM Zakeeruddin, J Luo, MT Mayer, M Grätzel, Nat. Commun., 2015, 6, 7326.

17.00 - 17.15 A1.O7 Maciejczyk, Michal
School of Chemistry, University of Edinburgh

Novel hole transporting materials based on spiro[fluorene-9,9′-xanthene] (SFX) and (diacetylide-triphenylamine) (DATPA) core

Michal Maciejczyka, Neil Robertson*a, Rosinda Fuentesa

School of Chemistry, University of Edinburgh, West Mains Rd , Edinburgh, EH9 3FJ, GB

Novel hole transporting materials based on cost-efficient spiro[fluorene-9,9′-xanthene] (SFX) have been recently reported by our group.1 Namely SFX-TAD, SFX-TCz, SFX-TPTZ and SFX-MeOTAD were fully characterized by 1H/13C NMR spectroscopy, mass spectrometry, XRD and DSC. Their thermal, optical and electrochemical properties were investigated. The use of different substituents affects the highest occupied molecular orbital (HOMO) energy level proving the versatility of the central core towards the facile and low-cost preparation of spiro-hole-transport materials. Among them, we have so far studied SFX-MeOTAD in detail for application in perovskite solar cells with device architecture glass/FTO/compact TiO2/mesoporous Al2O3/CH3NH3PbI3−xClx/HTM/Au. This material shows high glass transition temperature, high solubility, purely amorphous state and HOMO level alignment almost identical to spiro-MeOTAD. We show that devices employing SFX-MeOTAD show high power conversion efficiency up to 12.4%, compared with 13.0% for spiro-MeOTAD, but with the significant advantage of more than 5 times lower cost of synthesis. Furthermore, the easy synthesis of this series has enabled us to prepare examples of varying redox potential, offering a choice of HTM tailored to other emerging perovskite solar cell materials. Herein, we will show further development of SFX-based hole transporting materials as well as new materials based on DATPA (diacetylide-triphenylamine) core, previously reported in our group.2,3 In particular we studied the influence of tert-butyl and different alkoxy groups on materials properties like film forming quality, energy levels, crystallinity/amorphousness, thermal stability, solubility and device performance.

1. M. Maciejczyk, A. Ivaturi and N. Robertson, J. Mater. Chem. A, 2016, 4, 4855–4863.

2. M. Planells, A. Abate, D. J. Hollman, S. D. Stranks, V. Bharti, J. Gaur, D. Mohanty, S. Chand, H. J. Snaith and N. Robertson, J. Mater. Chem. A, 2013, 1, 6949.

3. A. Abate, M. Planells, D. J. Hollman, V. Barthi, S. Chand, H. J. Snaith and N. Robertson, Phys. Chem. Chem. Phys., 2015, 17, 2335–2338. 

17.15 - 17.30 A1.O8 Noel, Nakita
University of Oxford

A Low Viscosity, Low Boiling Point, Clean Solvent System for the Rapid Crystallisation of Highly Specular Perovskite Films

Nakita Noela, Severin Habisreutingera, Bernard Wengera, Matthew Kluga, Maximilian Hoerantnera, Michael Johnstona, Robin Nicholasa, David Moorea, Henry Snaith*a

University of Oxford, Clarendon Laboratory, Parks Road, Oxford, 0, GB

Perovskite-based photovoltaics have, in recent years, become poised to revolutionise the solar industry. While there have been many approaches taken to the deposition of this material, one-step spin-coating remains the simplest and most widely used method in research laboratories. Although spin-coating is not recognised as the ideal manufacturing methodology, it represents a starting point, from which more scalable deposition methods, such as slot-dye coating or ink-jet printing can be developed. Here, we introduce a new, low-boiling point, low viscosity solvent system that enables rapid, room temperature crystallisation of methylammonium lead triiodide perovskite films, without the use of strongly coordinating aprotic solvents. Through the use of this solvent, we produce dense, pinhole free films with uniform coverage, high specularity, and enhanced optoelectronic properties. We fabricate devices and achieve stabilised power conversion efficiencies of over 18 % for films which have been annealed at 100˚C, and over 17 % for films which have been dried under vacuum and have undergone no thermal processing. This deposition technique allows uniform coating on substrate areas of up to 125 cm2, showing tremendous promise for the fabrication of large area, high efficiency, solution processed devices, and represents a critical step towards industrial upscaling and large area printing of perovskite solar cells.

Session B1
Chair: Filippo de Angelis
14.30 - 15.00 B1.IS1 Schmidt-Mende, Lukas
University of Konstanz

Charge generation at organic-inorganic hybrid interfaces

Philipp Ehrenreicha, Eugen Zimmermanna, Lukas Schmidt-Mende*a

University of Konstanz, Universitaetsstr. 10, POB M680, Konstanz, 78457, DE

The stability of metal-oxides in combination with unlimited design possibilities of organic semiconductors make hybrid solar cells a promising candidate for future solar cell application. Contrary to expectations, charge generation has turned out to be less efficient in comparison to fully organic solar cells. Beside charge separation, also charge collection has been demonstrated to be affected by significant losses. In this contribution we present some fundamental findings on major loss mechanisms that can occur in a charge separation process. We will show that Coulomb forces in a charge transfer states are rather strong and geminate recombination is enhanced. In this context we will discuss the role of trap states in the metal oxide as well as the relevance of energy cascades or Förster resonant energy transfer. Both, electronic measurements on solar cell devices as well as time-resolved spectroscopy results are presented for organic-inorganic hybrid interface and compared to fully organic donor-acceptor interfaces.

15.00 - 15.15 B1.O1 Moons, Ellen
Karlstad university

Photodegradation of polymer solar cell materials

Rickard Hanssona, Leif K.E. Ericssona, Vanja Blazinica, Ellen Moons*a

Karlstad university, Universitetsgatan 1, Karlstad, 65188, SE

After two decades of research, organic photovoltaics has now reached record efficiencies above 10%, strongly competitive processing costs and shorter energy payback times. To break through as a reliable technology, these advantages need to be accompanied by an acceptable durability. Enhancing the stability of OPV modules, which are continuously exposed to external factors such as light, heat, in-diffusing oxygen and humidity, is the next critical issue.

We focus here on the photodegradation in air of the active layer materials in polymer solar cells. We have studied changes in composition and electronic structure of the fullerene derivative PC60BM, the conjugated polymer TQ1, and blends of those, using near-edge X-ray absorption fine structure (NEXAFS), X-ray Photoelectron Spectroscopy (XPS) and FT-IR spectroscopy. Despite the strong photobleaching of pure TQ1 films in air, we find that the lowest occupied molecular orbital (LUMO) of pure TQ1 films is almost unaffected by exposure in air to simulated solar light (AM1.5). On the contrary, exposure of pure PC60BM films in air to light affects its occupied as well as its unoccupied molecular orbitals. This change is assigned to a transition of sp2 to sp3 hybridized carbons in the C60 cage, as a consequence of photo-oxidation and possible photo-oxidation products are suggested, based on experimental and DFT-calculated FTIR and NEXAFS spectra. Moreover, when these changes to the electronic structure of TQ1 and PCBM films are compared to those in TQ1:PC60BM (1:3) blend films, we found that the photo-degradation of PC60BM is accelerated by the presence of TQ1, while the TQ1 is protected by the fullerene. 

15.15 - 15.30 B1.O2 Míguez, Hernán

Strong quantum confinement effects in perovskite nanocrystals by supramolecularly templated scaffolds

Miguel Anayaa, Andrea Rubinoa, Mauricio Calvoa, Juan Galisteoa, Hernán Míguez*a

ICMS (CSIC-US), C/Americo Vespucio 49, Seville, 41092, ES

The reduction of the size of a semiconductor crystal below the exciton Bohr radius represents a very versatile strategy to tune its optical properties as a consequence of the quantum confinement effects induced.[1]

In this talk, we will discuss about our recent advances on the spatial confinement of MAPbI3 nanocrystals.[2] We employ a novel strategy that consists on the synthesis of perovskite crystallites within supramolecularly templated mesostructured metal oxide films that display an ordered three-dimensional pore network. The fine control over the pore sizes of the inorganic films allows us obtaining MAPbI3 nanocrystals with narrow size distribution and radius from 1 nm to 4 nm, adjustable by the template selected. The resulting ensembles show stable optical properties on demand over a wide range of 0.34 eV (wavelengths from 640 nm to 775 nm), which are representative of the strong quantum confinement regime. The high optical quality of the materials is maintained over several squared centimeter areas, opening the path to the fabrication of perovskite-based optoelectronic devices with performances governed by quantum size effects.

[1] A. D. Yoffe, Adv. Phys. 1993, 42, 173.

[2] M. Anaya et al. Adv. Opt. Mater. 2017. DOI: 10.1002/adom.201601087.

15.30 - 15.45 B1.O3 Trifiletti, Vanira
Università del Salento

Engineering Titania based Planar Heterojunction for Hysteresis-Less Perovskite Solar Cells

Vanira Trifiletti*a, b, Norberto Manfredib, Andrea Listortia, c, Davide Altamurad, Cinzia Gianninid, Silvia Colellaa, c, Giuseppe Giglia, c, Aurora Rizzoc

a, Università del Salento, Via per Arnesano, LECCE, 73100, IT
b, Milano-Bicocca Solar Energy Research Center, Via Cozzi 55, MILANO, 20125, IT
c, CNR-Nanotec, Via Monteroni, LECCE, 73100, IT
d, CNR Istituto di Cristallografia, Via Amendola 122/O, BARI, 70126, IT

We adopted a procedure to achieve an optimised CH3NH3PbI3 layer in a planar TiO2 based Planar Heterojunction, which finally results in hysteresis-less and high-efficiency solar cells. We explored the optimisation of the perovskite film thickness, by using a super-saturated solution of CH3NH3I and PbI2 precursors, which also impact on the quality and size of perovskite domains, and the fine-tuning of the perovskite layer surface by a thermal-vacuum post-deposition treatment. Using this procedure, we have obtained a pinhole-free perovskite film with large grain size, reduced surface defects, and generate high photovoltaic performance almost independent on the voltage scan direction. Through photophysical characterization, we proved that the fine setting of the combined thermal-vacuum treatments results in extra-large grains, simultaneously offsetting film defect concentration. Our finding suggests how hysteresis can be efficiently stemmed by simply optimising perovskite processing conditions targeting different device layouts.[1] Moreover, we present a well know p-type doping material as an additive for the Hole Transport Material (HTM), 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane, i.e. F4TCNQ: we have tested various doping concentration in the two most used HTM material for perovskite-based solar cells, Spiro-OMeTAD and P3HT, defining the best doping condition and testing stability in months.  



[1] Trifiletti, V.; Manfredi, N.; Listorti, A.; Altamura, D.; Giannini, C.; Colella, S.; Gigli, G.; Rizzo, A. Engineering TiO2/Perovskite Planar Heterojunction for Hysteresis-Less Solar Cells. Advanced Materials Interfaces 2016, 3, 1600493.

15.45 - 16.00 B1.O4 Shen, Qing
The University of Electro-Communications

Slow Hot Carrier Cooling in Bulk CsPbI3 Perovskite and CsPbI3 Quantum Dots

Qing Shen*a, Feng Liua, Teresa Ripollesb, Naoki Nakazawaa, Yaohong Zhanga, Yuhei Ogomib, Koji Nishinakab, Taro Toyodaa, Shuzi Hayase*b

a, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182, JP
b, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu, Kitakyushu 808-0196, JP

 Lead halide perovskites are attracting a great deal of interest for optoelectronic applications such as solar cells, LEDs and lasers because of their unique properties. In solar cells, heat dissipation by hot carriers results in a major energy loss channel responsible for the Shockley–Queisser efficiency limit. Hot carrier solar cells offer the possibility to overcome this limit and achieve energy conversion efficiency as high as 66% by extracting hot carriers [1]. Therefore, fundamental studies on hot carrier relaxation dynamics in lead halide perovskites are important. On the other hand, very recently, all-inorganic cesium lead halide (CsPbX3) perovskite solar cells show the potential for making stable photovoltaic devices, even more stable than the standard MAPbI3 solar cells [2-6], and phase stabilization can be reached in CsPbI3 quantum dot (QD) based solar cells [7].

In this study, we have investigated ultrafast photoexcited carrier relaxation dynamics, especially hot carrier cooling, in bulk perovskite CsPbI3 and CsPbI3 QDs using a transient absorption (TA) technique. We have clarified the hot carrier cooling dynamics in bulk CsPbI3 perovskite and CsPbI3 QDs. We find that a non-thermalized carrier population is created within a few 100 fs after excitation. Hot carriers cool slowly to reach the room temperature in a few 10 ps for higher photoexcited carrier density, which originates from a bottleneck of the carrier-phonon interactions. Most importantly, we find that hot carrier cooling can be slowed down a few times in CsPbI3 QDs compared to bulk CsPbI3. This result suggests that energy loss from hot carrier to phonons can be suppressed in the QDs, which may originate from quantum confinement effects in the QDs.

[1] R.T. Ross and A. J. Nozik, J. Appl. Phys. 53, 3813 (1982).  

[2] T. S. Ripolles, K. Nishinaka,Y. Ogomi, Y. Miyata, S. Hayase, Solar Energy Materials & Solar Cells 144, 532 (2016).

[3] G. E. Eperon, G. M. Paternò, R. J. Sutton, A. Zampetti, A.A. Haghighirad, F. Cacialli, H. J. Snaith, J. Mater. Chem. A 3, 19688 (2015).

[4] R. E. Beal, D. J. Slotcavage, T. Leijtens, A. R. Bowring, R. A. Belisle, W. H. Nguyen, G. F. Burkhard, E. T. Hoke, and M. D. McGehee,J. Phys. Chem. Lett.7,746 (2016).

[5] M. Kulbak, D. Cahen, G. Hodes et al., J. Phys. Chem. Lett. 6, 2452 (2015).

[6] S. Dastidar S. et al., Nano Letters 16, 3563-3570 (2016).

[7] A. Swarnkar A. et al., Science 354, 92-95 (2016).

16.00 - 16.30 Coffee break
Chair: Filippo de Angelis
16.30 - 16.45 B1.O5 Malinauskas, Tadas
Kaunas University of Technology

Quick & easy: efficient enamine hole transporting materials for perovskite solar cells

Tadas Malinauskas*a, Sanghyun Paekb, Zhiping Wangc, Maryte Daskevicienea, Michael Salibab, Kasparas Rakstysb, Artiom Magomedova, Henry J. Snaithc, Mohammad K. Nazeeruddinb, Vytautas Getautisa

a, Kaunas University of Technology, Kaunas, 50254, LT
b, École Polytechnique Fédérale de Lausanne, Lausanne, 1015, CH
c, University of Oxford, Oxford, OX1 3PU, UK

Hybrid organic-inorganic hybrid materials, particularly the perovskite family, have shown great promise for use in field-effect transistors, light-emitting diodes, lasers, tandems with silicon, plasmonics, sensors and photodetectors. In recent five years the power conversion efficiency of lead halide perovskite based thin film photovoltaic devices (PSC) has reached 22%. Although progress has been made on each layer, major emphasis was placed on perovskite film processing and relevant material design. Despite significant efforts dedicated towards development of new hole transporting materials the field is still dominated by costly 2,2´,7,7´-tetrakis(N,N-di-p-methoxyphenylamine)-9-9´-spirobifluorene (spiro-OMeTAD) and even more expensive poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA).

High cost of these HTM arises from the prohibitively expensive synthesis and purification procedures used. For example, spiro-OMeTAD is synthesized in five reaction steps that require low temperature, sensitive and aggressive reagents. In addition, high-purity sublimation-grade spiro-OMeTAD is required to obtain high-performance devices.

For some time now we have investigated possibilities to reduce synthesis complexity and ultimately price of the organic semiconductors. We have developed a new group of enamine-based hole transporting materials, which are synthesized via very simple route (one step, no expensive catalysts) from commercially available and relatively inexpensive starting reagents, resulting in up to one order of magnitude lower cost of the final product compared to the commercial spiro-OMeTAD. The materials have been tested in the perovskite solar cells and displayed high power conversion efficiency (up to 18%). These materials show great promise to become a viable p-type organic charge conductor to be employed in the scale-up and manufacturing of perovskite solar modules.

16.45 - 17.00 B1.O6 Agrios, Alexander G.
Department of Civil & Environmental Engineering, University of Connecticut

Attachment of nanocatalysts to bifunctional dyes for low-overpotential regeneration by iodide/triiodide

Bowen Yanga, b, Ian Weissc, Peter Catsoulisc, Elena Galoppinic, Alexander G. Agrios*a, b

a, Department of Civil & Environmental Engineering, University of Connecticut, 261 Glenbrook Rd U-3037, Storrs, CT, 06269, USA
b, Center for Clean Energy Engineering, University of Connecticut, 44 Weaver Rd U-5233, Storrs, CT, 06269, USA
c, Department of Chemistry, Rutgers University-Newark, 73 Warren St, Newark, NJ 07102, USA

The iodide/triiodide redox couple is by most criteria an excellent system for dye regeneration in dye-sensitized solar cells (DSSC). Both the oxidized and reduced forms are very cheap, highly soluble, small (for good mass transport), and have minimal light absorbance. The system has uniquely low rates of recombination with electrons in the photoanode (e.g. TiO2), which is often credited to the fact that even the oxidized species carries a negative charge. However, iodide requires a large overpotential (ca. 0.5 V) to reduce an oxidized dye molecule. This prompted an intense search for alternatives to iodide/triiodide that resulted in recent years in its replacement with cobalt(II/III) complexes. But these and other iodide/triiodide alternatives tend to be bulky and to exhibit rapid recombination, requiring very thin photoanode films. 

This group has been engaged in a collaborative project to overcome the overpotential problem by anchoring platinum nanoparticles to dye molecules. Recent results include the syntheses of novel ruthenium complexes containing carboxyl groups for attachment to TiO2 and a dithiolane unit for binding to Pt nanoparticles. The osmium analogue of one such complex has also been prepared, which has a significantly more negative HOMO level, allowing testing of the ability of Pt nanocatalysts to relieve the overpotential problem that limits its performance in DSSC devices. Characterization by cyclic voltammetry (both in solution and adsorbed to Pt), UV-vis and Raman spectroscopy, and X-ray photoelectron spectroscopy demonstrate attachment of Pt nanoparticles to the sulfur atoms of these molecules. Synthetic schemes, and results of these measurements and of DSSC devices, will be presented along with future directions for the study and improvement of molecularly tethered nanocatalysis in these and related systems.

17.00 - 17.15 B1.O7 Calabrò, Emanuele

Low Temperature solution process planar Perovskite Solar Module with an Aperture Area efficiency exceeding 10%

Emanuele Calabrò*a, Alessandro Lorenzo Palmaa, Fabio Matteoccia, Antonio Agrestia, Sara Pescetellia, Aldo Di Carloa

C.H.O.S.E., via Giacomo Peroni 400/402, Roma, 00131, IT

Organic/inorganic hybrid perovskite [1] shows to be a promising low cost, high efficient and solution processed photovoltaic (PV) technology with an impressive certified power conversion efficiency (PCE), of 22.1% [2]. To reduce the energy payback time of such PV technology, however, is it important to eliminate high temperature steps, for example that related to the sintering of the mesoscopic TiO2 scaffold. To this end, several investigation were made to find TiO2 alternative for the Electron Transporting Layer (ETL). One of the most promising Low Temperature (L-T) ETL material is the SnO2 [3] for his high transparency, high electron mobility and easy pinholes free solution deposition. This last aspect became fundamental for the up-scaling of high efficient large area cells and modules, to avoid recombination phenomena at FTO/perovskite interface. In this work we report the realization of  a n-i-p planar CH3NH3PbI3 based L-T Perovskite solar module (FTO/SnO2/CH3NH3PbI3/Spiro-OMeTAD/Au) with an Aperture Area Efficiency of 10.8%  (Aperture Area = 14 cm2) up-scaled from an high efficient (PCE=17.3%) small area cells (0.09 cm2). For both cell and module, the perovskite precursor is deposited via anti-solvent quenching method [4] to induce a rapid and homogeneous crystallization of perovskite layer. By using appropriate laser patterning (P1, P2, P3)  for the fabrication of monolithic series-connected module with 5 sub-cells [5], we were able to achieve a geometrical factor (ratio of active area/dead area from laser etching) of 91%, one of the higher value for a fully laser processed module. This upscaling process of a planar structure shows the possibility to realize low temperature efficient module by solution process that could be also used in flexible and tandem applications.        

[1] Lee, M. M. et Al. Science 338, 643–647 (2012).

[2]BestResearch-CellEfficiencies, ⟨⟩ (accessed February 2017).                      

[3] J. Song, et Al, J. Mater. Chem. A, 2015, 3, 10837-    10844.                                                                                                              

[4] N. Ahn, et Al, J.Am.Chem.Soc. 137(2015) 8696–8699.                                                                                                                             

[5] A. Palma et al. Submitted  

17.15 - 17.30 B1.O8 Edvinsson, Tomas
Uppsala University

Resonance Raman Spectroscopy of Hybrid Organometallic Perovskite Materials

Tomas Edvinsson*

Uppsala University, Box 534, Uppsala, 751 21, SE

Organo-metal halide perovskites (OMHPs) have recently emerged as very promising thin film solar cell materials and show remarkably high charge separation capabilities and defect tolerance. Halide substitution (I, Br, or Cl) in OMHPs influences the band gap, charge quantum yield, morphology, and local interaction with the organic cation. Here, as well as for A-cation exchange, the resonance Raman effect can be utilized to analyze both the possible change in charge transfer mechanism upon electronic excitation [1] and the intercalation progress during formation of the perovskites. [2] The approach was also used recently to study the mechanism of a room-temperature recrystallization using a strong Lewis base yielding planar perovskite thin film solar cells with remarkably high photovoltage (1.15 V) and over 18% power conversion efficiency for pristine CH3NH3PbI3.[3] The Raman and resonance Raman effect will here be briefly reviewed as well as the interpretations in terms of the change in the local symmetry and long-range order that give important clues for the mechanism of the crystal formation, providing a useful characterization tool that can be cross-correlated with other characterizations. [4] 


[1] Resonance Raman and Excitation Energy Dependent Charge Transfer Mechanism in Halide-Substituted Hybrid Perovskite Solar Cells, Park B., Jain S.M., Zhang X., Hagfeldt A., Boschloo B., Edvinsson T. ACS Nano, 2015, 9, 2088–2101

[2] Vapor phase conversion of PbI2 to CH3NH3PbI3: spectroscopic evidence for formation of an intermediate phase, Jain, S.M., Philippe, B., Johansson E. MJ. Park, B., Rensmo, H., Edvinsson,T., Boschloo, G. J. of Materials Chem. A, 2016, 4, 2630-2642

[3] Frustrated Lewis pair-mediated recrystallization of CH3NH3PbI3 for improved optoelectronic quality and high voltage planar perovskite solar cells  Jain, S.M., Qiu, Z. L Häggman, Mirmohades, M, Johansson, MB, Edvinsson, T., Boschloo, G. Energy & Environmental Science, 2016, 9 , 3770-3782

[4] Photoinduced Stark Effects and Mechanism of Ion Displacement in Perovskite Solar Cell Materials Pazoki, M , Jacobsson, TJ, Kullgren, J , Johansson, EMJ, Hagfeldt, A., Boschloo, G. and Edvinsson, T. ACS Nano (under revision)

Session C1
Chair: Wolfgang Tress
14.30 - 15.00 C1.IS1 Nogueira, Ana Flavia
University of Campinas

Perovskite Materials for LED and Solar Cells

Ana Flavia Nogueira*

University of Campinas, Instituto de Quimica, UNICAMP, Campinas, 13083970, BR

Perovskite materials have been extensively investigated as thin films or colloidal nanoparticles in several technological applications, such as photovoltaic cells (PV), lasers, photodetectors and light emitting diodes (LED). Perovskite is the name given to materials that have the general formula ABX3 with a structure similar to the mineral CaTiO3. In perovskite materials for PV, the monovalent cation “A” is an organic cation such a methylammonium (CH3NH3+, MA) or formamidinium (CH(NH2)2+, FA). For LED applications, “A” is an inorganic cation as Cs+. In both applications, “B” is a divalent cation Pb2+ or Sn2+, and “X” a halogen anion Cl-, Br- or I-. The optoelectronic properties that make perovskites attractive are their direct and tunable band gap, high absorption coefficient, ambipolar transport of charges, high mobility of electrons and holes compared with organic semiconductors, and electron diffusion lengths that can exceed micrometers in large crystals.

In this presentation we will discuss some aspects that limit or need to be improved in both PV and LED development.

Perovskite solar cells (PSC) are very sensitive to moisture and the highest reported efficiencies are for tiny devices assembled under very controlled conditions. A dry atmosphere found in glove boxes significantly increases equipment and operational costs for industrial processes; so ambient perovskite fabrication is much less expensive and thus more attractive. In our laboratory we prepare PSC under ambient conditions with efficiency of 13% by the intramolecular exchange method. We will discuss in more details how, by changing the deposition parameters, bulk perovskite formation occurs immediately, or thermal annealing is required to promote the full conversion. A new formation mechanism is proposed for perovskite materials prepared at ambient conditions.

Colloidal perovskite nanocrystals are promising for LED applications. The most used synthetic method to prepare them relies on a mixture of oleylamine and oleic acid (OA) as surfactants. The resulting nanocrystals exhibit poor colloidal stability due to facile proton exchange between the oleate and amine surfactants and the readily precipitate from the crude solution.Oleylamine itself can also accelerate the degradation of the nanocrystals. We will discuss an amine-free synthesis that utilizes tetraoctylammonium halides for preparation of OA-capped CsPbX3 PQDs without the need of post-anion exchange methods. The nanocrystals show PLQY of 70%, narrow emission spectra and enhanced colloidal stability. We will show the results of red,  green and blue (RGB) LED with utilizing solution-processed polymer based hole transport layers. 



15.00 - 15.15 C1.O1 Cappel, Ute
Uppsala University

Photo-induced effects of perovskite surfaces studied by photoelectron spectroscopy

Ute Cappel*a, Håkan Rensmoa

Uppsala University, Department of Physics and Astronomy, Uppsala, 75120, SE

Lead halide perovskites have raised a lot of attention in the scientific community due to their breakthrough power conversion efficiencies achieved in solar cells. The materials have developed from the initially used methylammonium lead iodide (MAPbI3) to structures containing two anions (Br- and I-) and several cations (formamidinium, MA, Cs+ and Rb+). Many aspects related to these materials still need to be understood including the materials’ photo-stability. Processes such as ion migration are likely to play a role in the photon to electron conversion mechanism and for the long term stability. 

In our constellation, we use X-ray based spectroscopies including photoelectron spectroscopy to study the electronic structure and related properties of functional materials and their interfaces at an atomic level. In these studies, we make use of advanced X-ray sources for example at synchrotron facilities. Specifically, the effect of external factors on the chemical distribution and on the electronic structure can be determined.  

In this talk, we will present a study of mixed-ion perovskite materials. The surface sensitivity of the measurements can be varied through a variation in the photon energy using Hard and Soft X-ray set-ups. Therefore, the distribution of the different elements in the perovskite structure from surface towards bulk can be determined. Moreover, implementing the new LowDose photoemission beamline at the synchrotron Bessy II, we combine a low photon flux with a highly efficient and high resolving spectrometer. This enables us to study the electronic structure of the perovskite surface without any X-ray degradation. At this beamline, a visible laser (515 nm) is available for pump-probe measurements. Using this laser, we were able to study how the perovskite surface is affected by illumination including effects on the chemical composition of the surface and on the Fermi level of the material. With our methods we directly follow ion migration processes and the surface chemistry induced by illumination.

15.15 - 15.30 C1.O2 Su, Tzu-Sen
National Tsing Hua University

Novel anodic co-electrodeposition for the fabrication of metal-doped electron transporting layer for high-efficiency perovskite solar cell

Tzu-Sen Sua, Tzu-Chien Wei*a

National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, Taiwan 30013, R.O.C., Hsinchu, Taiwan, 30013, TW

A perovskite solar cell (PSC) equipping with an efficient electron transporting layer (ETL) is considered most promising in terms of efficiency, reproducibility and hysteresis control. However, as the most commonly used ETL material, TiO2 has imperfect electrical properties such as unfavorable band position, low electron mobility and conductivity. To amend this, elemental doping is regarded as a paramount method to remedy these properties. In this study, we developed a unique method to deposit either n-type or p-type doped TiO2 ETL on FTO glass for PSCs by adding various metal salts such as Nb, Sn, and Co ions in a single electrodepositing bath. Electrodeposition is a bottom-up growth method which offers excellent controllability on both thickness and morphology of TiO2 film by simply manipulating the depositing parameters such as current density and applied voltage. The electrodeposited TiO2 film are characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to examine its morphology and crystalline structure. The optical and electrical properties of TiO2 ETL are measured by UV-Visible (UV-Vis), photoluminescence (PL), mott-schottky (MS) and electrochemical impedance spectroscopy (EIS). As a result, the Nb and Sn-doped TiO2 ETLs exhibit improved carrier density and conductivity, both are beneficial for improving the photovoltaic properties in PSCs. On the other hand, the Co-doped TiO2 ETLs increase the energy level of TiO2, leading to increase the Voc of device. Interestingly, we found that doping Nb, Sn and Co have minor effects on the energy alignment of TiO2 but significantly improve the cell performance. Our current analysis suggests that the carrier injection and charge extraction are the most two key factors in determining the quality of ETL and thus to achieve high efficiency of PSCs.

15.30 - 15.45 C1.O3 Lozano, Gabriel
Instituto de Ciencia de Materiales de Sevilla (CSIC-US)

A roadmap to design perovskite based tandem solar cells of superior performance

Gabriel Lozano*a, Miguel Anayaa, Mauricio Calvoa, Hernán Mígueza

Instituto de Ciencia de Materiales de Sevilla (CSIC-US), Americo Vespucio 49, Seville, 41092, ES

Optical design of perovskite solar cells (PSCs) has been demonstrated to boost the performance of this emerging photovoltaic technology.[1, 2, 3]

Recently, the research interest has put under the spotlight ABX3 perovskites for their application in tandem solar cells that can surpass the Shockley-Queisser limit.[4] In our talk we will discuss about the importance of optical modelling in order to optimize the performance of perovskite on perovskite tandem devices. In particular, we will analyse the potential of perovskite absorbers in which the lead cation is gradually substituted by tin. The tunability of their absorption onset in the spectral range from 780 nm to 1100 nm makes them ideal candidates for tandem applications. From the optical point of view, such cells are complex multilayered stacks in which both unwanted parasitic absorption and reflections are enhanced. In this regard, we combine semi-analytical models based on the transfer matrix and genetic algorithms to find the ideal device architectures that fully optimize light harvesting within the active layers. Designed solar cells are fabricated and simulations are experimentally confirmed with an in-depth electro-optical characterization.

[1] M. Anaya et al., Journal of Physical Chemistry Letters (2015), 6, 48-53.

[2] W. Zhang & M. Anaya et al., Nano Letters (2015), 15, 1698-1702.

[3] J.-P. Correa-Baena & M. Anaya et al. Advanced Materials (2016), 28, 5031–5037.

[4] M. Anaya & J.-P. Correa-Baena et al., Journal of Materials Chemistry A (2016), 4, 11214–11221.

15.45 - 16.00 C1.O4 Klug, Matthew
Department of Physics, University of Oxford

Tailoring Metal Halide Perovskites through Partial Cobalt Substitution

Matthew Kluga, b, Anna Osherovc, Amir Haghighiradb, Samuel Stranksc, d, Patrick Browne, Sai Baib, f, Jacob Wangb, Xiangnan Dangg, Vladimir Bulovićc, h, Henry Snaith*b, Angela Belcher*g, i, j

a, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK
b, Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA
c, The Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA
d, Department of Physics, University of Cambridge, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
e, Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA
f, Biomolecular and Organics Electronics, IFM, Linköping University, Linköping 58183, Sweden
g, Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA
h, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA
i, Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA
j, The Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA

As evidenced through a series of materials characterisation techniques, we demonstrate that partially substituting Pb2+ at the B-sites of the perovskite lattice is not restricted to Group IV elements but is also possible with at least Co2+. Adjusting the molar ratio of Pb:Co in the methylammonium mixed-metal triiodide perovskite affords new opportunities to tailor the material properties while maintaining stabilised device efficiencies above 16% in optimised solar cells. Specifically, crystallographic analysis reveals that Co2+ incorporates into the perovskite lattice and increasing its concentration can mediate a crystal structure transition from the cubic to tetragonal phase at room-temperature. Likewise, Co2+ substitution continually modifies the perovskite work function and band edge energies without either changing the band gap or electronically doping the intrinsic material. By leveraging this orthogonal dimension of electronic tunability, we achieve remarkably high open-circuit voltages up to 1.08 V with an inverted device architecture by shifting the perovskite into a more favourable energetic alignment with the PEDOT:PSS hole transporting material. 

16.00 - 16.30 Coffee break
Chair: Wolfgang Tress
16.30 - 16.45 C1.O5 Baran, Derya

Fullerene-free organic solar cells exceeding 1V open circuit voltage limit

Derya Baran*a, Iain McCullocha, James Durrantb, Thomas Kirchartzc

a, KAUST, King Abdullah University of Science and Technology, Building 5, level 3, office 3336, Thuwal, 23955, SA
b, Imperial College, Imperial College, Center for Plastic Electronics, SW7 2AZ, London, UK
c, FZJ, Forschungszentrum Julich, IEK-5, 52425, Julich, GE

Optimization of the energy levels at the donor–acceptor interface of organic solar cells has driven their efficiencies to above 10%. However, further improvements towards efficiencies comparable with inorganic solar cells remain challenging because of high recombination losses, which empirically limit the open-circuit voltage (Voc) to typically less than 1 V. Here we show that this empirical limit can be overcome using non-fullerene acceptors blended with the low band gap polymer PffBT4T-2DT leading to efficiencies approaching 10% (9.95%). We achieve Voc up to 1.12 V, which corresponds to a loss of only Eg/q − Voc = 0.5 ± 0.01 V between the optical bandgap Eg of the polymer and Voc. This high Voc is shown to be associated with the achievement of remarkably low non-geminate and non-radiative recombination losses in these devices. Suppression of non-radiative recombination implies high external electroluminescence quantum efficiencies which are orders of magnitude higher than those of equivalent devices employing fullerene acceptors. Using the balance between reduced recombination losses and good photocurrent generation efficiencies achieved experimentally as a baseline for simulations of the efficiency potential of organic solar cells, we estimate that efficiencies of up to 20% are achievable if band gaps and fill factors are further optimized.

16.45 - 17.00 C1.O6 Yang, Xudong
Shanghai Jiao Tong University

Large-area Uniform Perovskite Thin Films via Control of Morphology and Crystallization

Xudong Yang*a, Han Chena, Fei Yea, Wentao Tanga, Maoshu Yina, Liyuan Han*b

a, Shanghai Jiao Tong University, 800 Dongchuan Road, Minhang District, Shanghai, China, Shanghai, 200240, CN
b, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, 3050047, JP

As a promising high cost-performance photovoltaic technology, organometal halide perovskite solar cells (PSCs) have attracted great research attention owing to the high energy conversion efficiency and low-cost manufacture. However, most reported high efficiency PSCs were obtained by traditional spin coating method, which suffers the disadvantage in large-area film deposition with the material utilization ratio as low as only 1%. For devices based on non-spin-coating methods, the efficiency was relatively low due to the formation of structural defects in perovskite films, such as nanoscale pin-holes, dense crystal grain boundaries and rough borders. Here I would like to introduce a new method, namely soft-cover deposition (SCD), for the deposition of uniform perovskite films with high material utilization ratio. We control the film morphology and crystallization by controlling the processing key factors like surface wettability, solution viscosity and thermal evaporation temperature, etc. We made scaling-up, pinhole-free, large crystal grain and rough-border-free perovskite films over a large area of 51 cm2. The new deposition can be processed continuously in ambient air with a significantly enhancement in material utilization ratio of up to ~80%. This new method also enabled power conversion efficiencies of up to 17.6% on PSCs with working area of 1 cm2, leading to a higher overall cost-performance than that of spin coating method. We believe that the present SCD technology will benefit the low-cost fabrication of highly efficient perovskite solar cells and open a route for the deposition of other solution processed thin-films. Secondly, we also developed a technique for instant-crystallization of perovskite films without thermal annealing. The formed perovskite films exhibited large crystal grains. This instant-crystallization technique offers a way to simplify the device fabrication, which will reduce the cost of manufacturing efficient PSCs.


[1] Ye, F.; Chen, H.; Xie, F. X.; Tang, W. T.; Yin, M. S.; He, J. J.; Bi, E. B.; Wang, Y. B.; Yang, X. D.*; Han, L. Y.*, Energy Environ. Sci. 2016, 9 (7), 2295-2301.

[2] Yin, M. S.; Xie, F. X.; Chen, H.*; Yang, X. D.; Ye, F.; Bi, E. B.; Wu, Y. Z.; Cai, M. T.; Han, L. Y.*, J. Mater. Chem. A 2016, 4 (22), 8548-8553

[3] Chen H., Ye F., Tang W., He J., Yin M., Wang Y., Xie F., Bi E., Graetzel M.,* Yang X.D.,* Han L.Y.,* in submission.

17.00 - 17.15 C1.O7 Correa-Baena, Juan-Pablo

A Path Towards Lead-Free Perovskite Inspired Materials

Juan-Pablo Correa-Baena*

MIT, 77 Massachusetts Ave, USA

Perovskite solar cells (PSCs) have achieved certified power conversion efficiencies (PCEs) of 22.1% by low cost and low temperature solution processing. However, these materials are based on toxic lead and pose a threat to the commercialization efforts. Our efforts focus on screening criteria for defect-tolerant photovoltaic (PV) absorbers, identifying several classes of semiconducting compounds with band structures and dielectric constants similar to lead-halide perovskites. Further, we evaluate the carrier lifetimes of several Pb-free PV absorbers using a consistent combined experimental and theoretical approach. The carrier lifetimes of five candidate materials exceed 1 ns, a threshold for promising PV device performance. However, there are variations between these materials, and none achieve carrier lifetimes as high as those of the lead halide perovskites, suggesting that the understanding of defect-tolerant semiconductors are incomplete. Additional work is ongoing to add more complexity to our models to obtain Pb-free materials with charge carrier lifetimes that exceed 1 ns. 

17.15 - 17.30 C1.O8 Abate, Antonio
Helmholtz-Zentrum Berlin

Active Materials and interfaces for stable perovskite solar cells

Antonio Abate*

Helmholtz-Zentrum Berlin, Kekuléstraße 5,Berlin, D-12489 , Germany

Organic-inorganic perovskites are quickly overrunning research activities in new materials for cost-effective and high-efficiency photovoltaic technologies.  Since the first demonstration from Kojima and co-workers in 2009, several perovskite-based solar cells have been reported and certified with rapidly improving power conversion efficiency.  Recent reports demonstrate that perovskites can compete with the most efficient inorganic materials, while they still allow processing from solution as a potential advantage to deliver a cost-effective solar technology.Compare to the impressive progress in power conversion efficiency, stability studies are rather poor and often controversial.  An intrinsic complication comes from the fact that the stability of perovskite solar cells is strongly affected by any small difference in the device architecture, preparation procedure, materials composition and testing procedure.In the present talk, we will focus on the stability of perovskite solar cells in working condition.  We will discuss a measuring protocol to extract reliable and reproducible ageing data.  We will present new materials and preparation procedures which improve the device lifetime without giving up on high power conversion efficiency.

Session D1
Chair: Hiroshi Segawa
14.30 - 15.00 D1.IS1 Fabregat-Santiago, Francisco
Universitat Jaume I

Electrical properties of perovksite solar cells

Francisco Fabregat-Santiago*

Universitat Jaume I, Avda. V. Sos Baynat s/n, Castello, 12006, ES

Perovskite solar cells have made an extraordinary journey from 3.8% efficiency in 2009 to 22.1% in just 7 years. In the way, new phenomena such giant capacitance and different hysteretic phenomena found in the devices, have been puzzling researchers when trying to explain such responses and how to link them with the fundamental physicochemical properties of this material. The presence of hysteresis in the current density-voltage curve when performing a cyclic voltammetry, is generally ascribed to the presence of capacitances that introduce an extra contribution to current when sweeping the potential. In perovskite solar cells, a single capacitance is not enough to describe the hysteresis found in some systems. This work is focused on the description of the parameters that dominate the electrical response of the perovskite solar cell and are responsible of these characteristic behavior. Particular attention will be given to capacitive processes associated with ionic and electronic accumulation at interfaces and their effect on recombination, photovoltage and device hysteresis.

15.00 - 15.15 D1.O1 Kegelmann, Lukas
Helmholtz-Zentrum Berlin

Double-layer charge selective contacts in perovskite solar cells for improved device performance and reduced hysteresis

Lukas Kegelmann*a, Christian M. Wolffb, Celline A. Omondia, Felix Langa, Eva L. Ungerc, Lars Kortea, Thomas Dittricha, Dieter Neherb, Bernd Recha, Steve Albrechtd

a, Helmholtz-Zentrum Berlin, Kekuléstr. 5, Berlin, 12489, DE
b, University of Potsdam, Institute of Physics and Astronomy, Karl-Liebknecht-Str. 24–25, Potsdam, 14476, DE
c, Lund University, Department of Chemistry and NanoLund, Lund, 124, SWE
d, Helmholtz-Zentrum Berlin, Young Investigator Group Perovskite Tandem Solar Cells, Kekuléstr. 5, Berlin, 12489, DE

Solar cells made from inorganic-organic perovskites gradually approach market requirements as efficiency and stability improved tremendously in recent years. Planar low-temperature processed perovskite solar cells are advantageous for a possible large-scale production but are more prone to exhibit photocurrent hysteresis, especially in the regular n-i-p structure.

Here, a systematic characterization of different electron selective contacts with a variety of chemical and electrical properties in planar n-i-p devices processed below 180 °C is presented. The inorganic metal oxides TiO2 and SnO2, the organic fullerene derivatives C60, PCBM and ICMA as well as double-layers with a metal oxide/PCBM structure are used as electron transport materials (ETMs). Perovskite layers deposited atop the different ETMs with the herein applied fabrication method show a similar morphology according to scanning electron microscopy. Further, surface photovoltage spectroscopy measurements indicate comparable perovskite absorber qualities on all ETMs except TiO2 showing a more prominent influence of defect states. Transient photoluminescence studies together with current-voltage scans over a broad range of scan speeds reveal faster charge extraction, less pronounced hysteresis effects and higher efficiencies for devices with fullerene compared to metal oxide ETMs. Beyond this, only double-layer ETM structures substantially diminish hysteresis effects for all performed scan speeds and strongly enhance the power conversion efficiency up to a champion stabilized value of 18.0 %.

The results indicate reduced recombination losses for a double layer TiO2/PCBM contact design: First a reduction of shunt paths through the fullerene to the ITO layer. Second, an improved hole blocking by the wide band-gap metal oxide. Third, decreased transport losses due to an energetically more favorable contact as implied by photoelectron spectroscopy measurements. The herein demonstrated improvements of multi-layer selective contacts may serve as a general design guideline for perovskite solar cells.

15.15 - 15.30 D1.O2 Eames, Chris
University of Bath

Role of oxygen in degradation and photobrightening of CH3NH3PbI3

Chris Eames*a, Nic Aristidoub, Saif Haqueb, Jessica Dillona, Sam Stranksc, Saiful Islam*a

a, University of Bath, Department of Chemistry, GB
b, Imperial College London, Department of Chemistry, GB
c, University of Cambridge, Department of Chemistry, GB

Hybrid organic-inorganic lead halide perovskites have rapidly become a prime material for photovoltaic devices due to their high efficiency, strong light absorption, long carrier lifetimes and diffusion lengths, ease of large scale synthesis and defect tolerance. However, major concerns exist which may present barriers to commercialization, such as the presence of toxic lead and long term stability issues. A number of studies have shown that the archetypal composition methylammonium lead iodide CH3NH3PbI3 is fundamentally unstable1 to degradation in high temperatures, high illumination and environments that contain O2 and/or H2O.    

In this talk we show, using a range of experimental and computer modelling techniques, that CH3NH3PbI3 degrades more rapidly in environments containing both O2 and H2O than when just one of these is present. The possible degradation pathways of CH3NH3PbI3 are analysed to reveal that the presence of O2 provides alternative reaction routes in which hydrated phases are not formed, with a consequent increase in the heat of reaction. We show that the catalytic role of water is not to act as a proton donor in oxygen reduction, but to accelerate the breakup of the 3D perovskite structure to form the 2D PbI2 structure. This pathway leads to the  release of electrons and the reduction of O2 to form H2O via deprotonation of the CH3NH3+ organic cations. We suggest that iodide vacancies can act as sites for enhanced rates of oxygen reduction, and reveal how surface coatings of iodide containing salts can backfill the iodide vacancies to dramatically reduce the rate of degradation. Finally, we discuss the beneficial role of oxygen in photobrightening phenomena.

 1Snaith et al, Adv. Energy. Mater., 2015, 5, 1500963.

15.30 - 15.45 D1.O3 Hatton, Ross
University of Warwick

Plasmon-active silver and copper nanohole films as light-catching electrodes for organic photovoltaics

Jaemin Leea, Jessica Pereiraa, Oliver Huttera, b, Ross Hatton*a

a, University of Warwick, Department of Chemistry, Library Road, Coventry, CV47AL, GB
b, (Current address) Stephenson Institute for Renewable Energy, University of Liverpool, Department of Physics, L69 7ZF, GB

Organic photovoltaics (OPV) offer the possibility of exceptionally short energy payback times and low fabrication cost. Their low toxicity and compatibility with flexible substrates also makes them very well matched to a number of buildings integration, transportation and consumer electronics applications not accessible to conventional photovoltaics. However, the low charge carrier mobility in organic semiconductors constrains the thickness of the light harvesting layer to less than that needed to absorb all of the incident light over a broad range of wavelengths, particularly in the near-infrared part of the spectrum, which in turn limits device power conversion efficiency. One scalable approach to addressing this constraint, that has received relatively little attention to date but is well matched to OPV device architectures, is to trap the incident light as plasmonic excitations (i.e. collective oscillations of the conduction band electrons) at the surface of a metal electrode having a random array of sub-optical wavelength apertures [Ref. 1]. Similar to metal nanoparticles, nano-holes in a metal film can have a very large absorption cross-section, which enables strong coupling with plane wave incident light, whilst having the advantage of being confined to the plane of the electrode. Due to the very large absorption coefficient in many organic semiconductors, it is possible that this trapped light can be harnessed to directly excite electrons from the highest occupied molecular orbital to the lowest unoccupied molecular orbital in an adjacent organic semiconductor, before the plasmonic excitations dissipate their energy as heat due to ohmic losses in the metal. This talk will show, for the first time, how the low cost metal copper can be used for this purpose, and demonstrate an important advantage of this class of electrode over conducting oxide glass for practical applications. Together these findings provide a compelling motivation for the advancement of this class of window electrode.   

[1] H.M. Stec, R.A. Hatton, Plasmon-active nano-aperture window electrodes for organic photovoltaics, Adv. Energy Mater. 3 (2013) 193–199.

15.45 - 16.00 D1.O4 Barbero, David
Umea University

Nano-engineered PVs with enhanced efficiency

David Barbero*

Umea University, Chemistry Department, Umea, 90187, SE

Due to their very fast charge transport and ultrafast charge separation when mixed with a semiconducting polymer, carbon nanotubes are promising candidates for enhancing exciton dissociation and for transporting charges to the electrodes in a nano-carbon solar cell. Recently, we showed that nano-engineering of carbon nanotube networks embedded in a semiconducting polymer film strongly enhances charge transport through the nanotube network, even at very low tube loadings [1,2]. 

Here we demonstrate integration of a nano-engineered network inside the active layer of a photovoltaic device, and we test its performance under simulated sunlight. Our results show an enhancement of Jsc , FF, VOC compared to a traditional random network, and and increase in PCE by more than 2 fold. The importance of the nanotube loading, and applications to different designs (e.g. for perovskite PVs) will also be discussed.  



1. Nano-engineering of SWNT networks for enhanced charge transport at ultralow nanotube loading, D. R. Barbero, N. Boulanger, M. Ramstedt, J. Yu, Advanced Materials, 26 (19), 3111, 2014.

2. A solvent method to form ordered and highly conductive carbon nanotube nano-networks in a semiconducting polymer film, N. Boulanger and D. R. Barbero, Adv. Electr. Mater., 1(5), 1400030,2015.

16.00 - 16.30 Coffee break
Chair: Hiroshi Segawa
16.30 - 16.45 D1.O5 Jumabekov, Askhat

Dynamic Chemical Passivation of Absorber Layer Trap States and its Real-time Effect on the Device Performance in Back-Contact Perovskite Solar Cells

Askhat Jumabekov*

CSIRO, 002 - Offices 36 Gardiner Road, Clayton, 3168, AU

Hybrid organic-inorganic perovskites have been identified as one of the most promising classes of materials for photovoltaic and optoelectronic applications, due to their excellent electronic and optical properties, combined with their ease of fabrication. The efficiency of perovskite solar cells (PSCs) has increased at a remarkably fast pace, with the current maximum certified power conversion efficiency (PCE) reaching 22.1%. Conventional solid-state hybrid organic-inorganic perovskite-based solar cells have a sandwich type structure in which the perovskite absorber layer is positioned between bottom and top electrodes, typically a transparent conducting oxide (TCO) layer on glass, and an evaporated thin layer of gold or silver, respectively. Such an architecture for PCSs allows illumination of the cells only from the TCO side. Alternatively, the back-contact architecture offers the possibility of positioning both electrodes on one side of the absorber layer and shining light directly on the photoactive layer (1, 2). This helps to avoid the occurrence of transmission losses caused by the charge collecting TCO electrode in the conventional sandwich structure for PSCs, and may have some potential application in constructing four or two terminal tandem solar cell devices. The back-contacted device architecture is also useful for conducting fundamental studies as it has an exposed photoactive area, permitting in situ measurements on the effects of chemical treatment, passivation and annealing. I will present a successful application of back-contact PSCs (3) in studying the dynamic effect of a chemical passivation of the perovskite absorber layer and it is real-time influence on the device performance.



1.  P. Khoram, S. Brittman, W. I. Dzik, J. N. H. Reek, E. C. Garnett, Growth and characterization of pdms-stamped halide perovskite single microcrystals. J. Phys. Chem. C 120, 6475-6481 (2016).

2.  L. M. Pazos-Outón, M. Szumilo, R. Lamboll, J. M. Richter, M. Crespo-Quesada, M. Abdi-Jalebi, H. J. Beeson, M. Vrućinić, M. Alsari, H. J. Snaith, B. Ehrler, R. H. Friend, F. Deschler, Photon recycling in lead iodide perovskite solar cells. Science 351, 1430-1433 (2016).

3.  A. N. Jumabekov, E. Della Gaspera, Z.-Q. Xu, A. S. R. Chesman, J. van Embden, S. A. Bonke, Q. Bao, D. Vak, U. Bach, Back-contacted hybrid organic-inorganic perovskite solar cells. J. Mater. Chem. C 4, 3125-3130 (2016).

16.45 - 17.00 D1.O6 Munir, Rahim

Hybrid Perovskite Thin Film Formation from Solution: An In Situ Investigation of Microstructural Control through Solvent Engineering

Rahim Munira, Arif D. Sheikha, Yufei Zhonga, Ming-Chun Tanga, Ruipeng Lib, Detlef M. Smilgiesb, Aram Amassian*a

a, KSC, KAUST, Building 5, LFO34, KAUST, Thuwal, 23955, SA
b, CHESS, Cornell University, Ithaca, NY, USA, USA

Thanks to their excellent optoelectronic properties, organic-inorganic lead halide perovskite semiconductors have found their way into a variety of applications like solar cells, LEDs, sensors, etc. The ease of processing these perovskites through solution routes, such as spin-coating, blade-coating and spray coating makes them particularly attractive. Solvent engineering has recently emerged as a critical step for controlling the microstructural and morphological outcome of ink drying and solidification and has been shown to produce pin-hole-free films, justifying its broad adoption across the field. This talk will describe our recent investigations into the role of anti-solvent dripping on the solution-to-solid phase transformation of MAPbI3, FAPbI3 and FAxCs1-xPbI3 perovskite systems. To do so, we utilize a suite of in situ diagnostic probes including high speed optical microscopy, optical reflectance and absorbance, and grazing incidence wide angle x-ray scattering (GIWAXS), all performed during spin coating, to monitor the solution thinning behavior, changes in optical absorbance, and nucleation and growth of crystalline phases of the precursor and perovskite. Our investigations reveal that the choice of processing solvent, namely DMSO vs. GBL, and their ratios, strongly impact the effectiveness of the anti-solvent drip. Our time resolved observations reveal the anti-solvent drip must be applied before the crystallization of the precursor solvates, which also depends upon the solvent mixture, placing additional importance on the timing of the drip in achieving optimal morphology and device performance reproducibility. The insight provided by in situ studies should improve perovskite thin film manufacturability in terms of solar cell performance, yield and reproducibility.

17.00 - 17.15 D1.O7 Sajedi Alvar, Mohammad
Max-Planck Institute for Polymer Research

Absence of ferroelectricity in the perovskite MAPbI3

Mohammad Sajedi Alvara, Cristina Momblonab, Lidón Gil-Escringb, Hendrik Jan Bolinkb, Paul Bloma, Gert-Jan Wetzelaera, Kamal Asadi*a

a, Max-Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany
b, Instituto de Ciencia Molecular, Universidad de Valencia, Edificios Institutos de Paterna, Calle Catedrático José Beltrán Martínez, 2, 46980 Paterna, València, Spain

Hybrid organic-inorganic perovskites solar cells (PSCs) have reached power conversion efficiencies (PCE) in excess of 22%. Despite the great progress in the PCE, our understanding of the device physics is still in the early stages. One of the controversial issues around PSCs is the observation of the hysteretic behavior in current-voltage (J-V) characteristic of the cells. Three mechanism have been proposed for the observed behavior, namely ferroelectricity of the perovskite layer, ion movement, and charge trapping-detrapping. In our contribution we address whether ferroelectricity can be held accountable for the observed hysteresis. PSCs based on Methylammonium Lead Iodide (MAPbI3) were fabricated. Conventional ferroelectric test were performed to obtain the displacement loops as function of electric field (D-E loop) at different frequencies. Hysteretic D-E loops were typically observed at low frequencies. We rule out ferroelectricity as the origin of the observed hysteretic behavior. We suggest slow dynamic of mobile ionic charges as the origin of the observed hysteresis. The result obtained resolves a long standing yet controversial issue related to PSCs. 

17.15 - 17.30 D1.O8 Di Giacomo, Francesco
Holst Centre/TNO - Solliance

Up-scalable sheet-to-sheet production of high efficiency perovskite module and solar cells on 6-inch substrate using slot die coating

Francesco Di Giacomo*a, Santhosh Shanmugama, Henri Fledderusa, Weiming Qiub, Wiljan Verheesc, Maarten Dorenkamperc, Robert Gehlhaarb, Yulia Galagana, Herbert Lifkaa, Tom Aernoutsb, Sjoerd Veenstrac, Ronn Andriessena

a, Holst Centre/TNO - Solliance, High Tech Campus 21, Eindhoven, 5656AE, N, Eindhoven, 5611L
b, imec - Solliance, Thin Film PV, Leuven, B-3001, BE
c, ECN – Solliance, High Tech Campus 21, Eindhoven, 5656AE, NL

Organometallic halide perovskite are extremely promising novel materials for thin-film photovoltaics, exhibiting efficiencies over 20% [1]. This presentation will focus on the current status of one of the main challenges in the industrial development of this novel PV technology, the upscaling of the sheet-to-sheet (S2S) deposition of the constitutive layers aiming towards the roll-to-roll (R2R) production. Slot die coating was chosen as an upscalable technique for the deposition of the solution processed layers (perovskite and hole transport). 

A planar n-i-p structure was used in this work, with a Glass/ITO/TiOx/CH3NH3PbI3/Spiro-OMeTAD/Au stack of layers. A single step deposition (based on a Pb(CH3COO)2. (3 H2O) and PbCl2 mixed lead source) is adopted for the perovskite synthesis, enabling the reach of high PCE with relatively fast crystallization[2]. Amorphous TiOx was e-beam evaporated and gold was thermally evaporated. By coating the perovskite on a 152x152 mm2 glass/ITO by slot die coating is possible to dice out 16 small substrates with 4 cells each (0.16 cm2 ). The cells fabricated using this up-scalable method exhibit an average PCE of 14.6 ± 1.3 % (stabilized PCE of the best cell of each substrate gives a PCE of 14.2 ± 0.4 % with 300 s of tracking). The Jsc measured is confirmed by EQE. Preliminary stability measurement with MPPT at 1 sun show a T80 of about 250 hours (with a PCE starting from 14% and degraded to 11%).  

To enable the fabrication large area module also the slot die coating of Spiro-O-MeTAD layer was optimized, resulting in a stabilized PCE of 14.3%. Optimization of the “classic” P1, P2, P3 laser patterning results in modules with 95% geometrical fill factor. These modules were encapsulated with flexible R2R water oxygen permeation barrier and  PCE on aperture area up to 10-11% were measured (reverse JV scan).

  An outlook about the upscaling of a water based SnO2 ETL in combination with a double cation (Cesium Fromamidinium) perovskite will be provided, with insight about upscaling of the antisolvent and of the gas-quenching assisted crystallization process.


[1] NREL chart,     

[2] Qiu, W. et al. Pinhole-free perovskite films for efficient solar modules. Energy Environ. Sci. (2016). doi:10.1039/C5EE03703D

17.30 - 19.00 Posters/Exhibition and wine
23rd May 2017 - Day 2 (Tuesday)
General session G2
Chair: Mohammad Nazeeruddin
9.00 - 9.45 G2.K1 Nguyen, Thuc-Quyen
University of California Santa Barbara

Understanding Open-Circuit Voltage of Organic Bulk Heterojunction Solar Cells

Thuc-Quyen Nguyen*

University of California Santa Barbara, Department of Chemistry and Biochemistry, Santa Barbara, 0, US

Solution-processed organic solar cells potentially offer low cost, large area, flexible, and light-weight alternative energy sources. However, power conversion efficiencies (PCEs) and operational lifetimes of these devices are still low. The PCE of solar cells and their open circuit voltage (Voc) are directly related. In the majority of conjugated polymer:fullerene bulk heterojunctions (BHJ) solar cells, the Voc is significantly lower than the energy of photon absorption, as determined by the donor material bandgap (Eg). In this talk, I will discuss factors that affect Voc including energetic disorder, molecular orientation at the donor/acceptor interface, and charge recombination. While theoretical calculations have addressed questions about the importance of molecular orientation at the donor/acceptor interface, experimentally it is challenging to control molecular orientation to be edge-on or face-on, while maintaining identical contacts and a sharp donor/acceptor interface. I will introduce a system with which orthogonal molecular orientation is achieved, while maintaining identical contacts and a sharp donor/acceptor interface. Given a well-controlled donor/acceptor bilayer system, we uncover the genuine effects of molecular orientation on charge generation and recombination. We found that devices where the donor molecules are face-on to the acceptor interface suffer from less non-radiative recombination than edge-on devices. Non-radiative recombination significantly reduces the efficiency of solar cells and light emitting diodes, and thus must be minimized. Efficient charge generation is critical to photovoltaics and photodetectors. Answering the fundamental question regarding charge generation/recombination across donor-acceptor interfaces allows for continued development of improved solar cell devices and photodetectors. 

9.45 - 10.15 G2.I1 Snaith, Henry
University of Oxford

Metal halide perovskites: fundamental operation and advanced devices

Henry Snaith*

University of Oxford, Clarendon Lab, Parks Road,, Oxford, 0, GB

Over the last few years metal halide perovskites have risen to become a very promising PV material, captivating the research community. In the most efficient devices, which now exceed 22% solar to electrical power conversion efficiency, the perovskite is present as a solid polycrystaline absorber layer sandwiched between n and p-type charge collection contacts. Increasing importance of improving solar cell operation is reliant upon understanding and controlling thin-film crystallisation and controlling the nature of the heterojunctions between the perovskite with the p and n-type charge extraction layers. In addition, understanding and enhancing long term stability of the materials and devices if a key driver. Despite the competitive efficiency, and assuming that stability challenges will be surmountable, for perovskites to feasibly enter the PV market, the commercial modules need to deliver something which other technologies cannot: Their unique selling point is ease of tuning the band gap, which can deliver both hybrid and all-perovskite multi-junction solar cells, with a feasibility of much higher efficiency than current commercial flat plate PV technologies. I will highlight the key factors which are important for reaching the maximum efficiencies, and also areas where we know require further improvement. I will specifically highlight recent advances in understanding the thin film crystallisation and enhancing the long term operational stability through compositional design of the perovskite, in addition to appropriate choice and adaptation of charge selective contacts. I will demonstrate efficient perovskite solar cells with band gaps ranging from 1.2 to 1.8 eV and show these materials integrated into hybrid tandem solar cells with silicon and all perovskite monolithic 2-terminal tandem cells. As part of improving the materials and devices, knowledge of the fundamental operational mechanisms within the thin films and devices is required. I will present some of our recent studies in understanding the optoelectronic properties of metal halide perovskites.   

10.15 - 10.45 G2.I2 Janssen, Rene
Eindhoven University of Technology

Material design toward practical useful polymers for efficient polymer solar cells

Rene Janssen*

Eindhoven University of Technology, ,

For future commercialization of semiconducting polymers for organic solar cells a high efficiency is not the only important factor, but aspects like easy synthesis, processing from non-chlorinated solvents, and being able to employ thick layers (> 200 nm) are likewise crucial to enable roll-to-roll manufacturing. Presently, only a few polymers afford high efficiencies at active layer thickness exceeding 200 nm and molecular design guidelines for developing successful materials are lacking. We found that alternating, but random copolymerization of benzodithiophene and two matched fluorinated benzothiadiazole monomers forms a successful approach to synthesize state-of-the-art semiconducting polymers for practical application in polymer solar cells. Over a reasonable range of compositions, the random copolymers provide power conversion efficiencies (PCEs) of about 8.0% with little batch-to-batch variation, even when the active layer is deposited from non-halogenated solvents at room temperature. In the same family of polymers we also studied the critical role of thiophene rings introduced in the backbone to investigate the fill factor and overall efficiency for thick layer solar cells. We established a steady increase of the fill factor and power conversion efficiency when introducing thiophene rings between the donor and acceptor units. The increased performance is a synergistic result of an enhanced hole mobility and a suppressed bimolecular charge recombination, which we attribute to more favorable polymer chain packing and finer phase separation. In single-junction cells these materials provide efficiencies of about 8%, almost independent of layer thickness up to 250 nm.

10.45 - 11.15 Coffee Break
Chair: Mohammad Nazeeruddin
11.15 - 11.45 G2.I3 Han, Liyuan
National Institute for Materials Science

High Performance of Perovskite Solar Cells: from Cells to Modules

Liyuan Han*

National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047 JAPAN, Tsukuba, 305, JP

Perovskite solar cell (PSC) unprecedentedly developed in recent years due to its excellent photovoltaic performance and simple solution processing method. Here I will introduce our main achievements obtained from inverted PSC devices with working area over one centimetre square. Firstly, reproducibility of device performance is improved through controlling the morphology and uniformity of perovskite layer and charge extraction layers in the solar cells. The thick charge extraction layerswith high conductivity, such as NiO and TiO2 heavily doped with Mg2+ , Li+ and Nb5+ , are usedto reduce pinhole of the film and increase the long-term stability of device.1 Secondly, we develop efficient inverted-structure with a perovskite-fullerene graded heterojunction (GHJ), which is featured with a gradient distribution of electron accepting material in the light absorption perovskite layer. This structure is found capable of enhancing the PCE of inverted structured PSCs as it improves the photoelectron collection and reduces recombination loss, especially for the formamidinium (FA) cation based perovskites that have superior spectra response and thermal stability. The conformal fullerene coating on perovskite during the GHJ deposition facilitates a full coverage of fullerene with reduced layer thickness, thus minimize the resistive loss in larger size devices. By employing this strategy, we have achieved certified efficiency exceeding 19.2% based on a cell with an aperture area greater than one centimetre square.2 Furthermore, the cost of PSCs module is simulated and key factors to lower the cost of PSCs modules are concluded as efficiency of a proper device structure and the long-term stability. The costs of modules are found to be only one third of that of commercial silicon solar cells.3

 (1) Chen, W.; Wu, Y.; Yue, Y.; Liu, J.; Zhang, W.; Yang, X.; Chen, H.; Bi, E.; Ashraful, I.; Graetzel, M.; Han, L. Science 2015, 350, 944.

(2) Wu, Y.; Yang, X.; Chen, W.; Yue, Y.; Cai, M.; Xie, F.; Bi, E.; Islam, A.; Han, L. Nature Energy 2016, 1, 16148.

(3) Cai, M.; Wu, Y.; Chen, H.; Yang, X.; Qiang, Y.; Han, L. Advanced Science 2016, 1600269. 

11.45 - 12.15 G2.I4 Leite, Marina
University of Maryland

Mapping perovskites electrical response with nanoscale spatial resolution

Marina Leite*

University of Maryland, 2123 Chemical and Nuclear Engineering Building, College Park, 20742, US

Despite the rapid development of hybrid perovskite photovoltaics, fundamental questions concerning the mechanisms for moisture and light-induced reactions that can cause material degradation are still open, including the device performance dynamics upon illumination. Macroscopic light I-V’s as a function of time generally show power conversion efficiency changes within ~50 seconds after illumination. Nevertheless, it is unknown how the solar cells’ electrical response varies locally. To spatially and temporally resolve the local electrical response of perovskites upon operation we implement and apply a novel 4D microscopy tool, based on illuminated Kelvin probe force microscopy (KPFM), in a low humidity environment (< 15%). We observe nanoscale variations in open-circuit voltage Voc > 300 mV, not revealed by conventional microscopy tools. Using fast-KPFM (16 seconds/scan) while maintaining high spatial sensitivity, we map, in real-time, the dynamics of the Voc in perovskite solar cells with nanoscale spatial resolution. Surprisingly, we measure a ‘residual Voc’ post-illumination, where it takes certain regions of the sample ~10 minutes to reach equilibrium under dark conditions. We attribute this residual photovoltage to iodine ion migration, a process that takes place in similar time scale. Our results show, for the first time, the real-time and nanoscale transient behavior of the Voc in perovskites. Understanding the light-induced electrical changes that affect device performance is key to the further advancement of stable perovskite-based photovoltaic devices. Further, our functional imaging can be extended to probe the stability of other systems, such as lead-free perovskites.  

12.15 - 12.45 G2.I5 Seok, Sang Il
School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST)

Inorganic charge transporting layers for highly efficient and stable perovskite solar cells

Sang Il Seok*

a, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919, KR
b, Korea Research Institute of Chemical Technology, 141 Gajeong-Ro, Yuseong-Gu, Daejeon, 305, KR

We have been remarkably improved the performance of perovskite solar cells (PSCs) by introducing a mediator to retard the rapid crystallization between organic cations and PbI2 via solvent engineering and intramolecular exchange process. Now a day, it was proved that our process is very effective in fabricating efficient PSCs. Nevertheless, we have found that TiO2 used as electron transporting layer (ETL) can significantly reduce the stability of PSCs under illumination including ultraviolet light. Therefore, the development of a new type of charge transporting layer ensuring long-term stability and a high performance is extremely important. We prepared Sn-based oxides for the use in inorganic ETL at a mild condition and applied to PSCs. In addition, we fabricated PSCs using a low temperature solution-processed copper thiocyanate (CuSCN) as inorganic hole transporting layer. The PSCs fabricated with La-doped BaSnO3 (LBSO) and methylammonium lead iodide (MAPbI3) show a steady-state PCE of 21.2%, which is the highest value ever reported for MAPbI3 PSCs (PCE = 19.7% for mp-TiO2­­­). Furthermore, the PCE of LBSO-based PSCs retains 93.3% of its initial performance after 1,000 h of full sun illumination (including ultraviolet light).

12.45 - 13.00 Sponsor talk: Dyesol
13.00 - 14.30 Lunch
Session A2
Chair: Lukas Schmidt-Mende
14.30 - 15.00 A2.IS1 Tarasov, Alexey
Faculty of Materials Science, Lomonosov Moscow State University

New fabrication strategy of perovskite films via direct reaction of metallic lead with polyiodide melts at room temperature

Alexey Tarasov*a, b, Andrey Petrova, Alexey Grishkoa, Michael Graetzelc, Eugene Goodilin*a, b

a, Faculty of Materials Science, Lomonosov Moscow State University, Lenin Hills, Moscow, 119991, RU
b, Department of Chemistry, Lomonosov Moscow State University, Lenin Hills, Moscow, 119991, RU
c, Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering École Polytechnique Fédérale de Lausanne (EPFL), Station 6, CH-1015 Lausanne, Switzerland, CH

We present a new effective strategy of perovskite films preparation for optoelectronic applications, in particular, solar cells using novel reactant compounds - reactive polyiodide melts and lead precursors. The reactive polyiodide melts (RPM) can be easily obtained from solid I2 and MAI (I2 and FAI), exhibit very low melting points and high chemical activity. Being liquid at room temperature, they alleviate the need to use a solvent for the conversion of metallic lead to perovskite CH3NH3PbI3.

Using this innovative approach, we demonstrate that a thin layer of metallic lead can be converted instantly into polycrystalline perovskite films of high electronic quality at room temperature. The reaction between the metallic lead and reactive polyiodide melts proceeds rapidly without solvents or additional agents. Depending on the preparation conditions, two types of morphology are obtained - sphere-like and cubic crystals of perovskite. The latter case gives high quality perovskite films with large crystals exhibiting intense photoluminescence with lifetimes longer than 200 ns.

There are several advantages of the proposed method of producing of thin film of lead-halide perovskite. The first one is the use of the thin film of lead as a precursor that can be deposited in a controllable way using a large number of standard techniques such as sputtering, galvanostatic deposition, etc. on different substrates, including flexible ones. Thus the thickness of the perovskite layer can be easily controlled. The second advantage is the speed of conversion that is orders of magnitude higher than can be reached in a two-step approach using CH3NH3I in i-PrOH. We also show that mixed perovskites MAxFA1-xPbI3-xBrx can also be easily obtained using this strategy. In particular, single-phase MA-stabilized FAPbI3 with long charge carriers lifetimes was obtained.

This work was supported by Ministry of Education and Science of Russian Federation, project identification number: RFMEFI60716X0148

15.00 - 15.15 A2.O1 Guerrero, Antonio
Institute of Advanced Materials (Universidad Jaume I)

External Interfaces Limit Perovskite Electrical Response

Antonio Guerrero*

Institute of Advanced Materials (Universidad Jaume I), Avda. Sos Baynat, s/n Universidad Jaume I , Castellon de la Plana, 12006, ES

Photovoltaic devices based on lead halide perovskites have received much attention due to the high power conversion efficiency obtained and due to the interesting physical properties. In this presentation the electrical signatures of ion migration towards the perovskite/external interfaces is explained in terms of J-V response, open circuit voltage decay and impedance spectroscopy.1 Pristine devices show distinct features that are not matched by devices that have been polarized using different external stimuli. Importantly, ion accumulation at the contacts can be monitored by using capacitive techniques and electrical models based on classical liquid electrolytes are suitable to explain the capacitive response.2,3 It is shown that ions accumulation can ultimately lead to chemical reactivity with the external contacts. For example, iodide ions can react with the oxidized form of spiro-OMeTAD leading to a reduction of conductivity of the hole selective layer. Alternatively, devices fabricated in the inverted configuration can be dramatically affected by ions reaching the external interfaces.4



Financial support by Spanish Ministerio de Economía y Competitividad for a Ramón y Cajal Fellowship (RYC-2014-16809) is acknowledged.


1. J.P. Correa-Baena, S. H. Turren-Cruz, W. Tress, A. Hagfeldt, C. Aranda, L. Shooshtari, J. Bisquert, A. Guerrero, Submitted.

2. J. Carrillo, A. Guerrero, S. Rahimnejad, O. Almora, I. Zarazua, E. Mas-Marza, J. Bisquert, G. Garcia-Belmonte, Advanced Energy Materials 2016, 6 (9), 1502246.

3. O. Almora, A. Guerrero, G. Garcia-Belmonte Applied Physics Letters 2016, 108 (4), 043903.

4. A. Guerrero, J. You, C. Aranda, Y.S. Kang, G. Garcia-Belmonte, H. Zhou, J. Bisquert, Y. Yang ACS nano 2016, 10, 218–224.

15.15 - 15.30 A2.O2 Ruseckas, Arvydas
University of St Andrews

Triplet exciton formation by non-geminate recombination in PTB7:PC71BM blends

Arvydas Ruseckas*a, Scott Pearsona, Gordon Hedleya, Ifor Samuela

University of St Andrews, Physics and Astronomy, St Andrews, 0, GB

The triplet state energy in small-bandgap semiconducting polymers is lower than the energy of charge transfer states which makes recombination to the triplet state energetically feasible and opens a new loss mechanism in OPVs. Triplet exciton can react with oxygen and lead to chemical degradation of OPVs, hence it is important to understand how they form in order to seek ways to minimise triplet formation.  

In this work we combine broadband transient absorption spectroscopy with time-resolved fluorescence to probe the population of radical cations, triplet excitons and singlet charge transfer states (CTs) in efficient PTB7:PC71BM blends. We use time-dependent carrier mobility measured by integral-mode photocurrent to describe the encounter rate of non-geminate charge pairs and to model the observed recombination dynamics. We find that singlet CTs predominatly dissociate again and their recombination probability is less than 1% whilst the probability for triplet CTs to recombine into triplet excitons is about 4% . The results can be explained using Marcus theory suggesting that recombination to triplet states can be reduced by tuning energetics of electron donor and acceptor.

15.30 - 15.45 A2.O3 Ito, Seigo
University of Hyogo

N2 Blow Drying Method for Perovskite Solar Cells with NiO and Low-Temperature Carbon

Seigo Ito*

University of Hyogo, 2167 Shosha, Himeji, 671, JP

As a fully-printed solar cells without vacuum deposition, nitrogen-blowing method has been performed to crystalize CH3NH3PbI3 perovskite layer inserted in NiO porous layer as p-type material for the fabrication of mesoscopic printable perovskite solar cell (PSC) using low-temperature processed carbon as the counter electrode.  The main electrode was screen-printed porous TiO2/ZrO2/NiO electrodes on <glass/FTO/compact TiO2>.  Using NiO as the hole transporting material into the structure, the thick capping perovskite layer deteriorated the photovoltaic phenomena, significantly, which can be removed by the nitrogen blowing.  Without the MAPbI3 capping layer obtained by N2 blow drying method, the good charge transportation has been confirmed by electrochemical impedance spectroscopy (EIS).  The best photovoltaic performance was a short-circuit current density (Jsc) of 22.38 mA cm-2, an open circuit voltage (Voc) of 0.97 V, and a fill factor (FF) of 0.50 corresponding to a PCE of 10.83%.  It was confirmed that the stability over 1000 hrs in the air in the dark by un-encapsulated device. 

15.45 - 16.00 A2.O4 Ugur, Esma
King Abdullah University of Science and Technology(KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE)

The Effect of Glycol Ether Addition on Charge Carrier Dynamics and Photovoltaic Performance of Solution-Processed Planar Perovskite Solar Cells

Esma Ugura, Jafar I. Khana, Arif D. Sheikha, Rahim Munira, Erkki Alarousua, Dounya Barrita, Aram Amassiana, Frédéric Laquai*a

King Abdullah University of Science and Technology(KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), King Abdullah University of Science and Technology, Thuwal, 23955-6900, SA

Organometallic halide perovskite solar cells have reached power conversion efficiencies (PCE) of more than 21%, yet only when a mesoporous electrode structure is used. These mesoporous charge transport layers require a high temperature (≥ 500 °C) annealing step during device fabrication. In contrast, the planar device architecture is more practical for large scale production, flexible devices, and tandem applications since it is possible to fabricate these solar cells at lower temperatures (<150 °C), but the efficiencies are still lower than for mesoporous perovskite devices. Thus, enhancing the PCE of planar perovskite photovoltaic devices is crucial to make this technology competitive with current photovoltaic technologies. In this study, we studied the effect of adding glycol ethers, namely 2-methoxyethanol, 2-ethoxyethanol and 2-propoxyethanol, to the methylammonium iodide (MAI) solutions prior to processing the perovskite thin films. We found that the addition leads to more compact, pin-hole free and better reproducible perovskite absorber layers. Moreover, improved conversion of lead iodide (PbI2) to methylammonium lead iodide (MAPbI3) was observed. Specifically, the addition of 2-methoxyethanol to the precursor solution resulted in improved perovskite crystal growth with the average grain size reaching up to 1 µm.  This in turn led to a considerable enhancement of the photovoltaic performance from 14.3% to 16.7%, largely due to an improvement in fill factor (FF) from 62% to 68%. We attribute this enhancement of device performance to enlarged grain size and vertical orientation of crystals in the perovskite layer plus more efficient conversion of PbI2 to MAPbI3. At this point, we attribute the improved layer properties to changes in grain growth, as we observed remained DMF solvent in the precursor layers. This is supported by in-situ UV-vis absorption experiments that also showed different PbI2 to MAPbI3 conversion dynamics during the spin coating and annealing processes. Furthermore, we performed ultrafast transient absorption spectroscopy (TAS) and time-resolved photoluminescence (TR-PL) spectroscopy to investigate the effect of glycol ether additives on the photophysical processes in perovskite solar cells. 

16.00 - 16.30 Coffee break
Chair: Lukas Schmidt-Mende
16.30 - 16.45 A2.O5 Momblona, Cristina
University of Valencia

Highly efficient vacuum deposited perovskite solar cells employing doped charge transport layers

Cristina Momblonaa, Lidon Gil-Escriga, Jorge Ávilaa, Daniel Pérez-del-Reya, Pablo P. Boixa, Michele Sessoloa, Henk J. Bolink*a

University of Valencia, C/ Catedrático José Beltrán, 2, Paterna - Valencia, 46980, ES

Hybrid organic-inorganic perovskites have become one of the most promising photovoltaic materials, with power conversion efficiencies beyond 20%. Most of these certified solar cells are processed from solution, and the perovskite layer is deposited from toxic solvents such as dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) on (mesoscopic) metal oxides. Vacuum techniques are solvent-free with advantageous intrinsic characteristics such as a precise control over the film thickness and composition, low-temperature processing, and the possibility of preparing multilayer structures. Moreover, vacuum techniques are widely used in the electronic industry, making them a viable alternative to solution-based processing of perovskite thin films. In previous works, the implementation of evaporated perovskite films into solar cells where the perovskite layer is sandwich between organic layers made by solution processed lead to efficiencies lower than 15%. Here, we present the preparation and optimization of fully vacuum deposited perovskite solar cells employing doped organic charge transport layers with efficiencies that overpass this limit of 15%. In these device, a thin film of methylammonium lead iodide perovskite is sandwiched between doped electron and hole transport layers (n- and p-type, respectively). We perform a direct comparison between two common configurations, one inverted with respect to the other (p-i-n and n-i-p), highlighting the effect of the conductivity and transparency of the transport materials on the overall device performance. This configuration leads to planar solar cells without hysteresis and high efficiencies, 15% for p-i-n and 18% for n-i-p on average.1 We will also show our recent results on vacuum deposited multiple cation perovskite absorbers and their use in efficient solar cells.

1C. Momblona; L. Gil-Escrig; E. Bandiello; M. Sessolo; E. M. Hutter; K. Lederer; J. Blochwitz-Nimoth; H. J. Bolink. Energy Environ. Sci., 2016, 9, 3456-3463.

16.45 - 17.00 A2.O6 Genevicius, Kristijonas
Vilnius University

The investigation of recombination processes by extraction of the injected charge carriers

Kristijonas Genevicius*a, Gytis Juskaa, Egidijus Kamarauskasa

Vilnius University, Saulėtekio al. 5, Vilnius 10221, LT

The recombination of the charge carriers is one of efficiency limiting factors in solar cells. In contrast to organic bulk heterojunction cells, recombination process in perovskite or dye-sensitized solar cells takes place in a small part of cell between electron (ETL) and hole transporting (HTL) layers. In this case, most of techniques which have been used in bulk heterojunction solar cells are not applicable.

We are proposing technique based on extraction of injected charge carriers by linearly increasing voltage (i-CELIV) for estimation of recombination rate for the structures where recombination takes place in the area between electron and hole transporting layers. In those structures, in the case of low recombination rate, when injection takes place the current will be determined by the recombination rate in space between ETL and HTL. By applying extracting voltage (ramp or pulse) the charge accumulated in between ETL and HTL will be extracted and dependence between injection current and extracted charge could be established. This dependence could be further used for estimation of the recombination rate. We obtained analytical dependencies for two different cases: charge is not accumulating between ETL and HTL (extremely fast recombination) and all the charge is accumulated between ETL and HTL (extremely slow recombination). Experiment was performed in ETL/HTL and ETL/perovskite/HTL structures. The comparison of computer simulations with experimental results points that recombination coefficient depends on charge carriers concentration.

17.00 - 17.15 A2.O7 Wilson, Gregory
CSIRO Energy

Morphology Controlled Facile Perovskite Crystal Growth via a Uniform Metallic Seed Layer

Gregory Wilson*a, Timothy Jonesa, Robert Bennetta, Camilla Liana, b, Kenrick Andersona, Paul Marviga, Miheala Grigorea, Benjamin Ducka, Noel Duffya, Scott Donnea, b

a, CSIRO Energy, 10 Murray Dwyer Cct, Mayfield West, NSW, Australia, 2304, Australia
b, University of Newcastle, Department of Chemistry, Callaghan, NSW 2308, Australia

The field of perovskite solar cells (PSCs) is rapidly maturing and developments are progressing at an impressive rate. Current state of the art lead-salt derived PSCs has seen efficiencies exceeding 21%  for 0.1 cm2 and 15% for >1 cm2 research grade devices.Optimisation and improvement in device performance relies on design, morphology and crystal/defect chemistry of the perovskite, in addition to the structure and chemistry of selective contact materials used in cell fabrication. It is well known that for enhanced performance of PSCs, control of the perovskite crystal formation via deposition and annealing conditions has been the fundamental to improving device performance.1,2 Understanding the effort of morphology on performance has increased at an equally impressive rate especially the physical operation of both planar and mesoscopic assemblies, material microstructure and charge separation. Furthermore, approaches that enable scale-up (for example; spray coating, inkjet printing, slot-die coating and electrodeposition with 1cm2 efficiencies greater than 10%) have been steadily improving toward a commercially attractive manufacturing proposition.

Here we successfully demonstrate perovskite formation utilising a metallic seed layer, which can be readily deposited at large scale by several industrial methods, thus reducing a barrier for commercialisation: lateral scale-up. The photoactive perovskite semiconductor is obtained through tuning the chemistry of intermediate structures to provide facile and uniform crystalline materials. We report a novel approach for rapid and uniform coverage and an easily tuned final morphology of the perovskite on a transparent substrate. We have investigated the influence of deposition, intermediate- and perovskite-forming steps and optimised conditions to obtain high aspect ratios for surface coverage and density. The fundamental goal, in the diversity of deposition techniques trialled for perovskites, has been to drive the nucleation and crystallisation processes and to achieve uniform coverage of the underlying substrate with an optimal perovskite crystal morphology.  For the development of large area PSCs the ability to spatially correlate film properties will be essential for quality and optimisation of performance and we further demonstrate uniformity of our process via EL/PL imaging of films and devices. This talk will outline our process and progress to date on research grade, and larger, devices.

17.15 - 17.30 A2.O8 ,

b, .Department of Physics University of Gothenburg , G�teborg 41296, SE
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, JP
a, Helmholtz Zentrum Berlin, Hahn-Meitner-Platz 1, Berlin, 14109, DE
b, Albert-Ludwigs-Universit�t Freiburg, Fahnenbergplatz 79085 Freiburg, DE
a, Shri V. S. Naik Arts, Commerce And Science College, Raver (M.S.), India, Burhanpur Road, Raver, 425508, IN
a, VU University Amsterdam, De Boelelaan 1081, Amsterdam, 1081, NL
a, Zurich University of Applied Sciences, Wildbachstr. 21, Winterthur, 8401, CH
b, Laboratory of Photonics and Interfaces, EPF Lausanne, Lausanne, 1015, CH
a, LEPABE � Faculdade de Engenharia, Universidade do Porto, Rua Dr Roberto Frias, 4200-465 Porto, Portugal
b, IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de F�ısica e Astronomia, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal
c, Institut des Sciences et Ing�enierie Chimiques, Ecole Polytechnique F�ed�erale de Lausanne (EPFL), 1015 Lausanne, Switzerland
d, Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, 29208, USA
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, IPCMS, University of Strasbourg - CNRS, 23, rue du Loess, Strasbourg Cedex, 67034, FR
b, Institute f. Theoretical and Physical Chemistry, Chemistry Dept., W.-Goethe-University Frankfurt , 60438 Frankfurt, GE
a, Bar Ilan University, Ramat-Gan, Ramat-Gan, 52900, IL
b, Nanyang Technological University, 50 Nanyang Drive, Singapore
b, UMDO, Instituto de Ciencia de los Materiales, Universidad de Valencia, Valencia, 46071, ES
c, Center for Nano Science and Technology of Italian, via Pascoli 70/3, Milano, 20133, IT

Session B2
Chair: Ute Cappel
14.30 - 15.00 B2.IS1 Gibson, Elizabeth
School of Chemistry, Newcastle University

New anchoring groups for dye sensitized photocathodes

Elizabeth Gibson*a, Gareth Summersa, Fiona Blacka

School of Chemistry, Newcastle University, Newcastle upon Tyne, NE1 7RU,, GBversity, Bedson Bu

One way of improving the efficiency of dye-sensitized solar cells is to use two photoelectrodes in a tandem device, one harvesting the high energy photons, and the other harvesting the low energy photons.1 This enables the photovoltage to be increased, whilst maximizing light harvesting across the solar spectrum. Despite their promise, a tandem cell with a higher efficiency than the state-of-the-art “Grätzel” cell has not yet been achieved. This is because the performances of photocathodes are significantly lower than TiO2-based anodes. The small potential difference between the valence band of the NiO, p-type semiconductor, and the redox potential of the electrolyte and the faster charge-recombination reactions compared to the TiO2 system limits the efficiency. Previously, we increased the efficiency by varying the acceptor moiety in push-pull photosensitizers.3 This presentation will describe our recent work to investigate alternative anchoring groups to couple the dye to the metal oxide surface. The effect of the anchoring group on the cell efficiency and the rate of charge-transfer between the dye and NiO will be presented.


[1] E. A. Gibson, A. L. Smeigh, L. Le Pleux, L.Hammarström, F. Odobel,  G. Boschloo, A. Hagfeldt., Angew. Chem. Int. Ed. 2009, 48, 4402 –4405. [2] C. J. Wood, G. H. Summers, E. A. Gibson. Chem. Commun.2015, 51, 3915 – 3918. [4] Y. Hao,  C. J. Wood, C. A. Clark, J. A. Calladine, R. Horvath, M. W. D. H.-Heine, X.-Z. Sun, I. P. Clark, M. Towrie,   M. W. George, X. Yang, L. Sun, E. A. Gibson Dalton Trans., 2016, 45, 7708 – 7719; G. H. Summers, G. Lowe, J.-F. Lefebvre, S. Ngwerume, M.Bräutigam, B. Dietzek, J. E. Camp, E. A. Gibson: ChemPhysChem, 2017, DOI 10.1002/cphc.201600846; F. A. Black, C. J. Wood, S. Ngwerume, G. H. Summers, I. P. Clark, M. Towrie, J. E. Camp, E. A. Gibson Faraday Discussions, 2017, DOI: 10.1039/C6FD00228E

15.00 - 15.15 B2.O1 Qiu, Weiming

Improve the performance of perovskite modules through novel perovskite film formation and interface engineering

Weiming Qiu*a, b, Aniruddha Raya, Tamara Merckxa, Joao Bastosa, c, Lucija Rakocevica, c, Manoj Jaysankara, c, Robert Gehlhaara, David Cheynsa, Jef Poortmansa, c, Paul Heremansa, c

a, Imec, Kapeldreef 75, Heverlee, 3001, BE
b, MTM, KU Leuven, Kasteelpark Arenberg 44, Heverlee, 3001, BE
c, ESAT, KU Leuven, Kasteelpark Arenberg 10, Heverlee, 3001 , BE

Impressive progress has been made in perovskite photovoltaics during the past few years, boosting the power conversion efficiency (PCE) of small area perovskite solar cells up to 22.1%. This value is almost identical to that of the commercialized counterparts such as CdTe or CIGS based solar cells. However, the PCEs of perovskite modules, especially those with large areas, still lag behind those of small area devices. In this contribution, we present our recent progress on improving the perovskite layer formation and interface engineering, in order to get highly efficient perovskite solar modules. We will also show the fabrication of perovskite modules with high geometrical fill factor.

First of all, we developed a new precursor combination containing Pb(CH3CO2)2·3H2O, PbCl2, and CH3NH3I (MAI), which enabled us to fabricate pinhole-free MAPbI3-xClx layers on a large area.1 Spin-coated small area (0.13 cm2) perovskite solar cells reached a PCE of 17%, using a planar device structure of ITO/TiO2/perovskite/Spiro-OMeTAD/Au.By virtue of the uniformity of the perovskite film, perovskite solar modules with aperture areas of 4 cm2, 16 cm2, and 156 cm2 were obtained, showing aperture PCEs of 13.6%, 12.5% and 10.0%, respectively.  

Secondly, we improved the electron extraction by inserting a crosslinked phenyl-C61-butyric acid methyl ester (PCBM) layer between TiO2 and perovskite.2  PCBM was crosslinked by 1,6-diazidohexane (DAZH) in order to overcome the solvent incompatibility issue. With such interface layers and a mixed perovskite (FA)0.66(MA)0.34PbI2.85Br0.15 (FA =formamidinium), we improved the maximum PCEs of our small area devices and modules to 18.5% and 15% (4 cm2), respectively. Moreover, we achieved a certified aperture PCE of 12.9% from a 16 cm2 perovskite module. 

Finally, by using Cs/FA double-cation perovskites from a novel two-step method, we further increased the PCEs of small area devices and modules (4 cm2) to 19.3% and 16.4%, respectively. In addition, we show Cs/FA double-cation perovskites have significantly improved stability compared MA-contained perovskite, and are promising materials for stable perovskite solar cells. 

1. W. Qiu, T. Merckx, M. Jaysankar, C. Masse de la Huerta, L. Rakocevic, W. Zhang, U. W. Paetzold, R. Gehlhaar, L. Froyen, J. Poortmans, D. Cheyns, H. J. Snaith and P. Heremans, Energy Environ. Sci., 2016, 9, 484-489. 

2. W. Qiu, J. P. Bastos, S. Dasgupta, T. Merckx,  I. Cardinaletti,  M. V. C. Jenart, C. B. Nielsen, R. Gehlhaar, J. Poortmans, P. Heremans, I. McCulloch and D. Cheyns, J. Mater. Chem. A, DOI: 10.1039/c6ta08799j.

15.15 - 15.30 B2.O2 Tirado, Juan F.
University of Antioquia

Copper sulfide thin film as a low-cost p-type semitransparent electrode for ITO-free and hole-transporting-layer-free inverted-planar perovskite solar cells.

Juan F. Tirado*a, Daniel Ramireza, Rafael Betancura, Franklin Jaramillo*a

University of Antioquia, Calle 70 No. 52-21, Medellín, 1226, CO

New transparent-conductive electrodes (TCEs), including novel p-type materials, must be developed to achieve low-cost optoelectronic devices and next generation transparent electronics. In this work we report the synthesis of p-type copper sulfide thin films (CuxS) by spray pyrolysis and its use, for the first time, as semitransparent electrode in inverted-planar perovskite solar cells (PSCs). The resulting hole-transporting-layer-free and ITO-free device showed an unprecedented 5.96% efficiency (PCE). Photovoltaic behavior of the obtained PSCs was correlated with morphological, structural and optoelectronic properties of the CuxS films. In particular, covellite (CuS) and digenite (Cu1.8S) crystal phases were identified in the resulting CuxS film. The p-type nature of CuxS layers was confirmed by hot-probe method. Transparent electrode exhibited conductivity above 1000 S cm-1 which is comparable with state-of-the-art TCEs. Although CuxS presents a relatively low optical bandgap of 2.7 eV, the corresponding optical loss in the blue region reduces just marginally the obtained photogenerated current. Moreover, surface photo voltage (SPV) behavior of perovskite films grown on CuxS suggested that the use of our proposed TCE promotes perovskite films with less surface trap states than ITO. Total material cost per generated power (US$/W) was estimated for CuxS-based and ITO-based PSCs showing an impressive reduction of more than 34%. On the other hand the cost per area (US$/m2) was estimated as 6.78 US$/m2 and 13.77 US$/m2 for CuxS-based and ITO-based PSCs, respectively. Thus, using CuxS as TCE we observed a material cost per area (US$/m2) reduction of 50.72%. These results highlight the potential application of CuxS film as low-cost and scalable p-type semitransparent electrode in PSCs and other optoelectronic devices. 

15.30 - 15.45 B2.O3 Bartesaghi, Davide
Delft University of technology

Long-lived carriers found in double metal Cs2AgBiBr6 perovskite single crystals by TRMC

Davide Bartesaghi*a, b, Adam Slavneyc, Hemamala Karunadasac, Tom Savenijea

a, Delft University of technology, Van der Maasweg 9, Delft, 2629 HZ, NL
b, m2i, Elektronicaweg 25, 2628 XG Delft, NL
c, Stanford University, Departments of Chemistry, Stanford, 94305 California, USA

Lead-halide perovskites have recently attracted much attention due to their applicability in highly efficient photovoltaic devices. Aiming at a large-scale production of perovskite solar cells, replacement of Pb2+ with a non-toxic element is highly desirable. Double metal perovskites, in which Pb2+ is replaced by two metallic cations, have been recently proposed as a non-toxic alternative.   Here, we studied the charge carrier lifetimes in Cs2AgBiBr6 double metal perovskite single crystals by means of the time-resolved microwave conductance (TRMC) technique. This technique probes the generation and decay of mobile charges generated upon optical excitation by a short nanosecond laser pulse. We performed TRMC measurements at different temperatures and we varied both the wavelength and the intensity of the laser pulse. By varying the wavelength, the penetration depth of light can be tuned, thus controlling the location where charges are generated. For single crystals with a thickness exceeding the charge carrier diffusion length, wavelength-dependent measurements give the possibility of disentangling surface and bulk effects. When charges are generated close to the surface of a Cs2AgBiBr6 crystal (<500 nm), recombination is fast and occurs on a timescale of around 1 ns, which we attribute to surface recombination. Excitation close to the band-gap (600 nm) results in a rapid initial decay followed by a long-lived tail, which implies the presence of mobile carriers with a lifetime of many microseconds. The size of this long-lived TRMC signal increases upon rising the temperature; complementary temperature dependent pulse radiolysis microwave measurements show similar results as those obtained by TRMC measurements on optical excitation at 600 nm, excluding the option that the exciton binding energy prevents charge carrier formation. The long lifetime observed upon excitation at longer wavelengths is explained in terms of shallow trap states for excess minority carriers. We suggest that point defects in the crystals act as trap states; moreover, we propose that the tail of the TRMC signal is the result of thermally activated detrapping, explaining the rise with temperature. TRMC measurements on crystals grown under different conditions (e. g. in the presence of an excess of bismuth) exhibit different temperature dependent behavior in accordance with this model. Our results highlight the possibility of generating long-lived charge carriers in Cs2AgBiBr6 if surface recombination is suppressed, prompting surface passivation as the main aim of future research on this material.

15.45 - 16.00 B2.O4 Moon, Soo-Jin

Highly Efficient Organometallic Halide Perovskite Mini-modules Through A Full Laser Patterning Process

Soo-Jin Moon*a, Linus Löfgrena, Arnaud Waltera, Brett A. Kaminoa, Davide Sacchettoa, Florent Sahlib, Jérémie Wernerb, Matthias Bräuningerb, Bjoern Niesena, b, Julien Bailata, Sylvain Nicolaya, Christophe Ballifa, b

a, CSEM, Jaquet-Droz 1, Neuchatel, 2002, CH
b, EPFL, Maladière 71b, 2002 Neuchâtel, CH

Recently, a new class of thin film PV absorbers –the organometallic halide perovskite (PK)- has attracted a strong interest leading to an unprecedented boom in efficiency[1]. However, despite great efforts put into the race to boose cell performance, most of the reported results are obtained on devices with a scale significantly smaller than 1 cm2, with questionable stability. Therefore there is an urgent need to upscale this promising technology as well as to develop a set of material and encapsulation processes that will allow demonstrating its industrial viability.

In this work, we present our improvements of laser processes to pattern optimized P1, P2, and P3 interconnection lines on PK modules. We show that this technique is well-suited to scribe different module architectures (namely, scaffold and planar). Laser patterning can be applied to modules based on a mesoporous scaffold, as well as to planar devices deposited on organic charge transport layers. Moreover, we show that optimized laser parameters allow us to pattern different back electrodes, from metal to TCO-metal stacks. Finally, by combining the dead area reduction achieved by laser patterning with improved perovskite deposition techniques, a record steady-state efficiency of 16% on 14 cm2 aperture area was achieved in Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3 module. Thanks to the slightly higher band gap of the bromine containing perovskite compared to MAPbI3, a high open-circuit voltage > 8V was able to be obtained. We demonstrate our result with analysis to approach high performing and up-scaled perovskite solar cell.

[1]NREL, "NREL Efficiency Chart," 2 December 2016. [Online]. Available: [Accessed 10 January 2017].

16.00 - 16.30 Coffee break
Chair: Ute Cappel
16.30 - 16.45 B2.O5 Wu, Jiaying
Imperial College London

Influence of inadvertent doping on photocurrents in thick organic bulk heterojunction solar cells

Jiaying Wua, Hongkyu Kanga, James Durrant*a

Imperial College London, Room 133, Department of Chemistry, Imperial College London, South Kensington Campus, London, SW7 2AZ, GB

Although organic semiconductors used in photovoltaics are normally not inadvertent doped, significant unintentional doping levels have been previously reported in the literature. Here, we studied a relationship between device thickness dependence and doping levels in a broad range of donor and acceptor blends. Most of the blends presented a significant high apparent doping level on order of 1016 cm-3, resulting in small space charge regions around 100 nm thick at short circuit condition. This suggests that the photocurrent generation is only effective in space charge region. Moreover, we found that, in a wide range of polymer/acceptor systems, the inadvertent doping limiting the thickness of the space charge layer is actually a more important limitation of device thickness than non-langevin recombination (the literature has mainly focused on non-langevin recombination). As a result, we demonstrated that controlling a relatively low doing level in the blend is crucial to make thick cells while maintaining decent photocurrents. While the origin of the inadvertent doping is not clear yet, it was confirmed additional purification could reduce the doping density, and further study exploring the origin is being conducted. 

16.45 - 17.00 B2.O6 Hou, Yi
Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander University Erlangen-Nuremberg

A Universal Strategy to Overcome Hole-transporting Limitations in Organohalide Perovskite Solar Cells

Yi Hou*a, b, Christoph Brabeca, b, c

a, Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander University Erlangen-Nuremberg, Martensstr. 7, Erlangen, 91058, DE
b, Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Str.6, Erlangen, 91052, DE
c, Bavarian Center for Applied Energy Research (ZAE Bayern), Haberstr. 2a, Erlangen, 91058 , DE

Thin-film solar cells based on hybrid organohalide lead perovskites achieved power conversion efficiency exceeding 22% and are already on par with the well-established thin film photovoltaic technologies. One major bottleneck allowing to drive this technology further towards commercialization are the interfacial losses at the hole transporting contact. So far, all of the reported HTMs systems are limited in singular compounds, expensive materials, leaving few material choices and inevitably compromise device efficiency or stability. Developing a novel concept for solution processed, reliable, cost efficient and improved hole transporting materials which do not compromise efficiency, stability, and scalability, becoming of paramount importance and still challenging the perovskite community. Here, we present for the first time a novel interface concept, which combines solution-processed, reliable, and cost-efficient hole-transporting materials, without compromising efficiency, stability or scalability of perovskite solar cells. This multilayer interface offers a surprisingly small interface barrier and forms ohmic contacts universally with various scalable conjugated polymers. Time of flight secondary ion mass spectrometry (ToF-SIMS) further reveal that this interface is acting as a protective layer against the diffusion of Au into the perovskite. The absence of interface shunts is further suggested to enhance the stability of the corresponding perovskite devices. Using a simple regular planar architecture device, perovskite solar cells achieve maximum efficiencies of 19.0% combined with over 1000 hour of light stability, which is the highest performance so far for regular architecture perovskite solar cells using dopants-free HTMs.These findings open up the whole class of π-conjugated polymers, oligomers, and molecules as low-cost and scalable hole-transporting materials for perovskite optoelectronics without the need for additional ionic dopants. We believe that these findings open the whole class of π-conjugated polymers, oligomers and molecules as low-cost and scalable hole-transporting materials for perovskite optoelectronics without the necessity of additional ionic dopants. The universal strategy developed in this work will effectively maximum the performances of all the previous developed and broadly stimulate the material community to further design novel HTMs to follow the rules with optimum energetic levels. 

17.00 - 17.15 B2.O7 Wang, Jacob Tse-Wei
University of Oxford

Tailoring of Interfacial Layers in The Inverted Perovskite Solar Cells

Jacob Tse-Wei Wanga, Robin Nicholas*a, Henry Snaith*a

University of Oxford, Clarendon Laboratory, Parks Road, United Kingdom

Organic-inorganic halide perovskites have generated tremendous interest over the pastfew years. Many efforts have been made to improve the regular (n-i-p) architecture infacilitating charge extraction with improved selective contacts and deposition processesto further push the performance ahead. However, an anomalous hysteresis behaviour is widely observed in the regular structure, much worse than for the inverted (p-i-n) architecture. It has been pointed out, the cause of hysteresis is very likely to stem from unfavourable interfaces within the device. Therefore, it is important to understand the difference, and investigate the role of the interfaces in the two structures, so as to push up the device performance.

To explore the underlying mechanism of differences, where we have deconstructed the device layer by layer. Under a careful evaluation of the interface of individual components and energy level alignment, device performance has been examined and elevated. We also shown various approaches including piranha treatment, hot-solution casting, and the insertion of an orthogonal solution-based thin buffer layer, which have all contributed toward the improved wettability, surface morphology, and the better matching of energy levels between interfaces, leading to hysteresis-free perovskite solar cells. Compared with the regular structure employing fullerene as ETL, we found the existence of hysteresis may not be removed completely by the insertion of fullerene, but by a synergistic interaction between selective contacts which emphasize the importance of interface and interlayers.

Finally, we demonstrated an increase in Voc by up to 110 mV compared to the control devices. By exploiting a newly designed dopant with Poly-TPD as HTL, not only to improve the surface wetting for a much better interface, but also to increase hole-conductivity, hence, a much better HTM and superior device performance with PCE up to 20% can be achieved. Our works highlight the importance of understanding and controlling the solar cell fabrication process from the very beginning. And the careful optimisations throughout the entire carrier pathways have facilitated charge transportation, minimised unfavourable recombination, and enabled efficient and hysteresis-free inverted perovskite solar cells to be demonstrated.

17.15 - 17.30 B2.O8 El-Mellouhi, Fedwa
Hamad Bin Khalifa University

Balanced Electronic Coupling to Stabilize Hybrid Perovskite Materials

Fedwa El-Mellouhi*a, El Tayeb Bentriaa, Asma Marzouka, Sergey Rashkeeva, Sabre Kaisa, b, Fahhad H Alharbia

a, Hamad Bin Khalifa University, P.O. Box: 34110, Doha, 0, QA
b, 2Purdue University, West Lafayette, Indiana 47907,, USA

In the past few years, the solar cell community has witnessed an astonishing emergence of the hybrid perovskite solar cells (PSC) as a technology that can compete with the dominating silicon solar cell technologies. Efficiency-wise, it passed 22% in just four years. To illustrate how stunning this is, the main solar cell technologies (i.e. Si, CdTe, and CIGS) needed more than 40 years each to reach to such level. However and despite the remarkable advances, PSC is not ready for commercialization at the moment due to the severe stability issue. In short, the absorbing hybrid perovskite decomposes rapidly. This is not commercially acceptable as in solar cell industry, any solar panel is supposed to last for at least 20 years.Currently, it is well established that CH3NH3PbI3, which is the most widely used hybrid materials in PSC, is intrinsically instable. Other extrinsic causes make the situation even worse. Intrinsically, the electrostatic coupling between the commonly used organic cations (like methylammonium CH3NH3+ and formamidinium CH(NH2)2+) and the PbI6 three-dimensional octahedral framework is weak. Any other instability cause is conceptually inferior to this fundamental issue. In this work, we use first-principle calculations to show that it is possible to enhance the electronic coupling and consequently the stability of hybrid perovskite materials by replacing the molecular actions with others that allow stronger –yet balanced- electrostatic interaction. This is realized by forming hydrogen bonding. It is found as well that this alters the electronic states at the top of the valance band. So, it is important for solar cell applications to ensure that the optical gap is not affected strongly and that it is still within the suitable ranges for solar cells. Nonetheless, this can also provide a mean to tune the optoelectronic properties of hybrid perovskite materials (and hybrid materials in general) for other optoelectronic applications beyond solar cells as the exploited mechanism has a universal character.The calculations are performed using Density Functional Theory (DFT) with appropriate functionals and pseudopotentials. The stability is assessed by the reaction and hull energies and bonds formations. We explored wide range of possible molecular cations and found that CH3PH3+, CH3SH2+, and SH3+ cations result in highly stable hybrid lead iodine perovskites with suitable gaps for solar cells (1.81 eV, 1.55 eV, and 1.73 eV respectively).

Session C2
Chair: Marina Leite
14.30 - 15.00 C2.IS1 Ahmad, Shahzada
Abengoa Research, Abengoa

Protecting the perovskite layers by surface passivation to extend its lifetime

Shahzada Ahmad*a, Manuel Saladoa

Abengoa Research, Abengoa, C/ Energia Solar, Campus Palmas Altas, Sevilla, 41014, ES

Perovskites solar cells have emerged as a beacon in thin film photovoltaic technology. The power conversion efficiencies (PCE) has seen an over 200% jump in the last 5 years. To improve the inherent challenges, compositional engineering of perovskites as well as molecular engineering of hole transport materials (HTMs) were adopted. Device performance and stability was subsequently enhanced to an extent. However the intrinsic as well as extrinsic stability of perovskites remains problematic for its real commercial applications. The use of passivation layer on the backside is of utmost importance for silicon solar cells and currently being used for commercial production. A rear passivation layer of alternative functional material has not been yet employed in perovskite solar cells. While excess of PbI2 or an additional thin perovskite layer was recently use as an analogy.                                                        An optimized surface passivation layer is seen as an ideal approach to protect the surface from extrinsic attack, without altering the electro-optical properties. The judicious choice of passivation material is paramount for effective transfer of charges.                                                                                     We will describe our investigation on the utilization of a passivation layer, which protect the perovskite layer from atmospheric attack. An improved PCE was also obtained compare to reference devices, as the passivation layer will restricts the flow of electron towards the HTM layers and lower recombination was obtained. A batch-to-batch reproducibility with ±0.5% PCE was achieved along with very competitive efficiencies of 20%.

15.00 - 15.15 C2.O1 Fumagalli, Francesco
Istituto Italiano di Tecnologia

Introducing Organic Photoelectrochemical Water Splitting: High Performance Hybrid H2-evolving Photocathodes

Francesco Fumagallia, Sebastiano Bellania, Alessandro Mezzettia, Hansel Comas-Rojasa, Antonio Alfanoa, Laura Medab, Matthew Mayerc, Mariarosa Antognazzaa, Fabio Difonzo*a

a, Istituto Italiano di Tecnologia, via pascoli 70/3, milano, 20133, IT
b, Istituto ENI DOnegani, via fauser 40, novara, 28100, IT
c, Institut des Sciences et Ingénierie Chimiques, EPFL, , CH-1015 Lausanne, CH

Hydrogen production through renewable sources, rather than fossil fuels, represents the missing element towards a carbon neutral energetic cycle. One of the most promising approaches is the direct conversion of solar energy into chemical fuels at a low cost semiconductor/water junction. Despite the theoretical simplicity of such a device, different limitations on suitable semiconductor materials’ characteristics have hindered its development. In the last years, the capability of semiconductive polymers/fullerene-based acceptors compounds to steadily drive photo-generated electrons towards an electrocatalyst in a water environment was demonstrated. We present a study of different architectures of hybrid organic-inorganic H2 evolving photocathodes based on semiconducting polymeric absorbers. The relevance of this study can be summarized in few key points:(i) high performances with photocurrents up to 8mA/cm2 at 0VRHE;(ii) optimal process stability with 100% faradaic efficiency along electrode’s lifetime;(iii) excellent energetics with onset potential as high as +0.7VRHE;(iv) promising operational activity of more than 10 hours and (vi) by-design compatibility for implementation in a tandem architecture. Collectively, this set of features establishes hybrid architectures employing organic semiconductors and organic photoelectrochemical systems as promising candidates for efficient solar fuel production. Suitable materials were first investigated. Different PVD or solution processed inorganic interfacial layers (MoO3, WO3, CuI, TiO2/Pt) and their influence on performances have been assessed, enlightening the working principles and limiting factors of actual implementations. We show the photocatalityic activity and long-term stability of a catalysed bulk heterojunction and the effect of selective contacts on performances is investigated separately. Introduction of an electron selective layer increases the photocurrent response while hole blocking layers shift the onset potential towards positive voltages allowing operation with a tandem photoanode and/or a PV cell. Secondly the influence of system nanostructuration was assessed, the development of multi-layer systems based on structured absorbers in a host/guest architecture allowed us to orthogonalize light absorption and photogenerated carrier collection. Finally, seeking the realization of an efficient and cost-competitive photocathode we combined PVD and solution-processed techniques realizing a 2”x2” photoelectrode in order to show the potential of cheap, large-scale production of organic photoelectrochemical systems. Such a system exhibits 0.8mAcm-2 at 0VRHE, an onset potential of +0.7VRHE and stability of over 1hr. This work opens the way to the exploitation in photoelectrochemistry of organic semiconductors developed for OPVs and to the realization of a new generation of water splitting devices for renewable and low cost direct conversion of sunlight into H2.


15.15 - 15.30 C2.O2 Ummadisingu, Amita

Mechanism of perovskite formation and strategies for controlling morphology

Amita Ummadisingua, Michael Graetzel*a

EPFL, EPFL SB ISIC LPI, Station 6, Batiment CH , Lausanne, 1015, CH

Various deposition methods such as sequential deposition [1] and the anti-solvent method [2], have been developed for the preparation of perovskite solar cells, with major effort focused on achieving high performance [3]. However, factors controlling the final film morphology in perovskite formation in these deposition methods are little understood, as the underlying fundamental mechanisms are still unclear. Using tools including cathodo-luminescence, electrochemistry and PL mapping, we reveal the different stages of perovskite formation. Our study focuses on understanding the nucleation step and we present a detailed mechanism for our reaction system. We demonstrate novel strategies for tuning it, thereby establishing control over the resulting perovskite morphology, which is crucial for obtaining high performance [4, 5]. Our results shed light on previously unknown key variables governing perovskite film formation in different deposition methods, for various opto-electronic applications. 

[1] Burschka, J. et al. Sequential deposition as a route to high-performance perovskite-sensitized solar cells. Nature 499, 316-319 (2013). 

[2] Jeon, N. J. et al. Solvent engineering for high-performance inorganic-organic hybrid perovskite solar cells. Nature materials 13, 897-903 (2014). 

[3] Saliba, M. et al. Incorporation of rubidium cations into perovskite solar cells improves photovoltaic performance. Science 354, 206-209 (2016).

[4] Salim, T. et al. Perovskite-based solar cells: impact of morphology and device architecture on device performance. J. Mater. Chem. A 3, 8943-8969 (2015).

[5] Sharenko, A. & Toney, M. F. Relationships between Lead Halide Perovskite Thin-Film Fabrication, Morphology, and Performance in Solar Cells. Journal of the American Chemical Society 138, 463-470 (2016).

15.30 - 15.45 C2.O3 Langner, Stefan
University Erlangen-Nuremberg, Institute of Materials for Electronics and Energy Technology (i-MEET)

Organic solar cells processed from environmentally friendly solvent blends

Stefan Langner*a, Florian Winklerb, Jose Dario Pereaa, Florian Machuib, Tayebeh Ameria, Christoph J. Brabeca, b

a, University Erlangen-Nuremberg, Institute of Materials for Electronics and Energy Technology (i-MEET), Martensstraße 7, Erlangen, 91058, DE
b, Bavarian Center for Applied Energy Research (ZAE Bayern), Immerwahrstrasse 2, Erlangen, 91058, DE

Up to now organic solar cells (OSCs) are mainly fabricated via toxic semiconductor-inks, which are not only a strain on the human body and the environment, but require demanding and expensive safety standards as well. Halogenated solvents, such as chlorobenzene, chloroform or o-dichlorobenzene are widely used solvents for solution processed OSCs and need to be replaced. Therefore, the development of environmentally friendly photovoltaic-inks is a required step towards industrial fabrication of organic photovoltaics (OPV). For interface layers and electrodes alcohol and water-based coating methods already exist, but for the photoactive layer a powerful tool to predict suitable solvent/material combinations is still missing. Alternative solvents, reported by the community, are either chosen by trial-and-error method or are randomly selected so far. Here, the Hansen solubility parameters (HSP) analysis is used to find suitable solvents for various organic semiconductors. In the first step, we determined the HSP of selected organic semiconductors, such as polymers, fullerenes and small molecules. Secondly, the solubility of binary and ternary “green” solvent blends is measured to confirm the Hansen solubility model. Next, we used the HSP database and a self-written Matlab-code to design optimum solvent systems out of about 11,000 binary and 550,000 ternary environmentally friendly solvent blends. Finally, we investigated the most promising solvent combinations by engineering organic solar cell devices and analyzed their performance compared to a halogen-based fabrication of OSCs. Depending on the solubility it turned out that the HSP-model can predict different kinds of ink-formulations, which can be used for large area fabrication of OPV by roll-to-roll printing techniques.

15.45 - 16.00 C2.O4 Montcada, Nuria
ICIQ (Institut Catal� d'Investigaci� Qu�mica)

Analysis of Photo-Induced Carrier Recombination Kinetics in Flat and Mesoporous Lead Perovskite Solar Cells

Nuria Montcadaa, Jose Manuel Marin-Beloquia, Werther Cambaraua, Jesus Jimenez-Lopeza, Lydia Cabaua, Kyung Taek Chob, Mohammad Khaja Nazeeruddinb, Emilio Palomares*a

a, ICIQ (Institut Catal� d'Investigaci� Qu�mica), Av Paisos Catalans 16, Tarragona, 43007, Spain
b, 3Group for Molecular Engineering of Functional Materials, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1951 Sion,, Switzerland

In this work, we analyze the carrier recombination kinetics and the associated charge carrier density in methyl ammonium lead iodide perovskite (MAPI) solar cells that use mesoporous TiO2 as selective contact (m-MAPI) and flat solar cells (without the mesoporous TiO2, f-MAPI), which are the most common device architectures for perovskite solar cells. The use of PIT-PV (Photo-induced Transient Photo-Voltage) and L-TAS (Laser Transient Absorption Spectroscopy) showed that for devices that cannot reach efficiencies close to 19% there is a slow component of the photovoltage decay that corresponds to a charge recombination pathway for carrier losses responsible for the lower device efficiency. Moreover, we do have also identified a primary interfacial charge recombination pathway for carrier losses that is common in all devices studied, independently of their efficiency or their device structure, which we have associated with the recombination reaction between electrons in the perovskite and holes in the organic semiconductor material used as the selective contact.

16.00 - 16.30 Coffee break
Chair: Marina Leite
16.30 - 16.45 C2.O5 Jung, Hyangmi
Toshiba Corporation

Development of low temperature solution-processed perovskite photovoltaic cells and modules

Hyangmi Jung*a, Haruhi Oookaa, Shigehiko Moria, Hideyuki Nakaoa, Takeshi Gotandaa, Kenji Todoria, Yutaka Nakaia

Toshiba Corporation, 1, Komukai-Toshiba-cho, Saiwai-ku, Kawasaki, 212, JP

     We have developed low temperature solution-processed perovskite photovoltaics for flexible, lightweight and cost-effective devices on polymer substrates. Here, we report the development of large area perovskite photovoltaic cells and modules fabricated under 140 °C. The developed photovoltaics have planer structures of glass/ITO/hole transport layer/perovskite/PCBM/BCP/Ag. The PCEs have reached 14.5% on the cells with 1.0 × 1.0 cm2 of active areas, and 13.4% on the modules with 5.1 × 5.1 cm2 (da).

     To develop the large area cells, amount of N,N-dimethylformamide (DMF) in the cells were controlled by changing the annealing temperature of perovskite layers fabricated by spin-coating under gas-blowing[1]. As the annealing temperature deceased from 130 °C to 25 °C, the PCEs increased from 3.5% to 14.5% and the amount of DMF also increased. In addition, the low temperature annealed cells exhibited higher thermal stability under 85 °C than the high temperature annealed cells. The low temperature annealed perovskite exhibited extra shoulder peaks near 14.1° and 28.1° in XRD pattern. This suggests that the solvent coordinates with perovskite crystal and stabilizes the crystal. The grain sizes of the low temperature annealed perovskite were smaller than the high temperature annealed perovskite. This implies that the small grains densify the perovskite layer, which increases the efficiency and stability of the cells.

     To develop the high efficiency modules, we have focused on meniscus coating method, module design and device simulation. By our original meniscus coating method[2], buffer and perovskite layers were coated from nano- to micro-scaled thickness less than 3% variation. By the module design, narrow metal strips were installed on the edge on ITO electrodes to decrease damages on the ITO and power loss due to residuum after mechanical scribing process. By the device simulation, various parameters for the modules have been optimized using electrical field analyses and optical calculations. We have successfully developed the high efficiency modules with 13.4% by combining the knowledge from cell developments, the original techniques and the optimization. The efficiency and the size of our modules will be increased in the near future.

     This work was supported by the New Energy and Industrial Technology Development Organization (NEDO).

References [1] T. Gotanda et al., Chemistry Letters, 45, 822-824 (2016), [2] K. Todori et al., Toshiba review, Vol 69 , No 6 (2014)

16.45 - 17.00 C2.O6 Rong, Yaoguang
Huazhong University of Science and Technology

Efficient and stable printable mesoscopic perovskite solar cells

Yaoguang Ronga, b, Anyi Meia, Yue Hua, Mi Xua, b, Hongwei Han*a, b

a, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, Hubei, China, CN
b, Wonder Solar Limited Liability Company, 9 Fenghuang Road, Wutonghu District, Ezhou 436000, Hubei, China, CN

Mesoscopic perovskite solar cells (MPSCs) have captured intensive attention in the field of energy conversion due to the advantages of low material cost, simple fabrication process and high power conversion efficiency. Benefiting from the optimization of perovskite absorber deposition approaches, the design of new material systems, and the diversity of device concepts, the efficiency of MPSCs have increased from 2.19% in 2006 to a certified 22.1% in 2016. Such extremely fast increasing efficiency enables this photovoltaic technology challenge the current commercialized solar cells. However, typical perovskites of methylammonium lead halides (CH3NH3PbX3, X = Cl, Br, I) are usually sensitive to moisture in ambient air, and thus require an inert atmosphere to process. We demonstrate a moisture-induced transformation of perovskite crystals in a triple-layer scaffold of TiO2/ZrO2/Carbon to fabricate printable MPSCs. An additive of ammonium chloride (NH4Cl) is employed to assist the crystallization of perovskite, wherein the formation and transition of intermediate CH3NH3X·NH4PbX3(H2O)2 (X = I or Cl) enables high-quality perovskite CH3NH3PbI3 crystals with preferential growth orientation. Correspondingly, the intrinsic perovskite devices based on CH3NH3PbI3 achieve an efficiency of 15.6% and a lifetime of over 130 days in ambient condition with 30% relative humidity. This ambient-processed printable perovskite solar cell provides a promising prospect for mass-production, and will promote the development of perovskite-based photovoltaics.

17.00 - 17.15 C2.O7 Bonomo, Matteo
La Sapienza, University of Rome

New pyran based dyes for efficient p-DSSCs with NiO

Matteo Bonomo*a, Antonio Carellab, Roberto Centoreb, Aldo Di Carloc, Danilo Dinia

a, La Sapienza, University of Rome, Piazzale Aldo Moro 5, Rome, 179, IT
b, University of Naples Federico II, Corso Umberto I 40, Naples, IT
c, Centre for Hybrid and Organic Solar Energy (CHOSE), Department of Electronic Engineering, University of Rome TOR Centre for Hybrid and Organic Solar Energy (CHOSE), Department of Electronic Engineering, University of Rome TOR VERGATA, Via del Politecnico 1, Rome, IT

Three different pyran based dyes were tested as photosensitizers of NiO photocathodes ( thickness = 2 μm, active area 0.25 cm2) prepared via screen-Printing for p-DSSCs. The molecules feature a pyran core that is  functionalized with electron acceptor groups of different strength and symmetrically distributed with respect to the phenothiazine donor moieties. The optical properties of the dyes are strongly affected by the nature of the electron-acceptor group, so that the overall absorption of the three dyes covers the most of the visible spectrum.The photoelectrochemical properties of the corresponding p-DSCs are compared and analysed in terms of the structural differences of dyes. The properties of the solar conversion devices based on the sensitized cathodes here considered were measured under simulated solar radiation: JV curves and IPCE (incident photon-to-current conversion efficiency) spectra revealed the values of short circuit current density Jsc could easily approached 2 mA/cm2 and  power conversion efficiencies could reach values close to 0.07 %. The performances of the fabricated p-DSSC have been compared to a reference cell sensitized with a high level benchmark (P1), which afforded a conversion activity similar to the best of our devices (Jsc = 1.7 mA/cm2 and efficiency = 0.060 %). For the first time this study  demonstrates that dye-sensitizers (whose synthetic procedure is fast, easy and cheap)not having a tri-phenylamminic core can produce p-DSSCs with overall efficiencies in the order of 0.1%. 

17.15 - 17.30 C2.O8 Stolterfoht, Martin
Institute of Physics and Astronomy, University of Potsdam

Fill factor optimization strategies in efficient, stable triple cation perovskite solar cells

Martin Stolterfoht*a, Christian Wolffa, Yohai Amira, Andreas Paulkea, Dieter Neher*a

Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam-Golm, Germany

Perovskite solar cells (PSCs) now compete with their inorganic counterparts in terms of power conversion efficiency, not least because of their small open-circuit voltage losses. A key to surpass traditional thin-film solar cells is the fill factor (FF). Therefore, more insights into the physical mechanisms that define the bias dependence of the photocurrent are urgently required. In this work [1] we varied the organic electron/hole transport layers’ (ETL/HTL) thickness in efficient triple cation PSCs and studied the charge carrier recombination and transport through the device. Using integral time of flight we identify the transit time through the HTL as key figure of merit for maximizing the fill factor (FF) and efficiency. Complimentary, intensity dependent photocurrent measurements elucidate the role of the HTL thickness on the bias dependence of the recombination losses and recombination order. Via optimizing the transit time through the HTL we demonstrate efficiencies - under solar AM1.5G conditions - of 20.4% with high FFs up to 84% on 6 mm2 cells (19.2% efficiency on 0.5 cm2) and excellent stability under light illumination.  

[1]  Stolterfoht, M.; Wolff, C. M.; Amir, Y.; Paulke, A.; Neher, D. “Fill factor optimization strategies in efficient, stable triple cation perovskite solar cells,” Submitted to Nat. Energy, 2017.

Session D2
Chair: Chun-Guey Wu
14.30 - 15.00 D2.IS1 Etgar, Lioz
Hebrew University

Two Dimensional organic-inorganic perovskite from nanostructures to solar cells

Lioz Etgar*

Hebrew University, Edmond J. Safra Campus Givat Ram, Jerusalem, 91904, IL

Perovskite is a promising light harvester for use in photovoltaic solar cells. In recent years, the power conversion efficiency of perovskite solar cells has been dramatically increased, making them a competitive source of renewable energy.This work will discusses new directions related to organic inorganic perovskite and their applications in solar cells.  

1. In low dimensional systems, stability of excitons in quantum wells is greatly enhanced due to the confined effect and the coulomb interaction. The exciton binding energy of the typical 2D organic-inorganic perovskites is up to 300 meV and their self-assembled films exhibit bright photoluminescence at room temperature. In this work we will show the dimensionality in the perovskite structure. The 2D perovskite structure should provide stable perovskite structure compare to the 3D structure. The additional long organic cation, which is added to the perovskite structure (in the 2D structure), is expected to provide hydrophobicity, which will enhance the resistivity of the perovskite to humidity. Moreover we will demonstrate the use of 2D perovskite in high efficiency solar cells.  

2. Organometal halide perovskite is used mainly in its “bulk” form in the solar cell. Confined perovskite nanostructures could be a promising candidate for efficient optoelectronic devices, taking advantage of the superior bulk properties of organo-metal halide perovskite, as well as the nanoscale properties. In this work, we present facile low temperature synthesis of two-dimensional (2D) lead halide perovskite nanorods (NRs). These NRs show a shift to higher energies in the absorbance and in the photoluminescence compared to the bulk material, which supports their 2D structure. X-ray diffraction (XRD) analysis of the NRs, demonstrates their 2D nature combined with the tetragonal 3D perovskite structure. In addition, by alternating the halide composition, we were able to tune the optical properties of the NRs. Fast Fourier Transform, and electron diffraction show the tetragonal structure of these NRs. By varying the ligands ratio (e.g. octylammonium to oleic acid) in the synthesis, we were able to provide the formation mechanism of these novel 2D perovskite NRs. 2D perovskite NRs are promising candidates for a variety of optoelectronic applications, such as light emitting diodes, lasing, solar cells and sensors.


15.00 - 15.15 D2.O1 Knapp, Evelyne

Correlation between High Efficiency and Low Hysteresis

Evelyne Knapp*a, Martin T. Neukom*a, b, Stephane Altazinb, Simon Züflea, b, Beat Ruhstaller*a, b

a, ICP, ZHAW, Wildbachstr. 21,Winterthur, 8401, Swi
b, Fluxim AG, Technoparkstr. 2, Winterthur, 8406, Switzerland

There is increasing evidence for ion migration in methylammonium lead iodide perovskite solar cells. The electric field induced by the mobile ions affects the charge transport and is believed to be the origin of the hysteresis in IV-curves [1, 2]. The occurrence of hysteresis was also related to the contact layer materials [3]. Furthermore, highly efficient devices generally show low hysteresis. Hereby the following question arises: If mobile ions in the bulk are responsible for the IV-curve hysteresis, why does the hysteresis depend on the contact materials? We measure preconditioned IV-curves as proposed by Tress et al. [1] and use a numerical drift-diffusion model incorporating mobile ions to reproduce the measured effects. Using the numerical model we demonstrate why the hysteresis vanishes almost completely if contacts with a low surface recombination are used: With good contacts electrons and holes can also be extracted without an electric field as they can “pile up” at the opposite interface and diffuse to the interface where they are extracted. This finding is consistent with the study of Philip Calado and Piers Barnes that find evidence for ion migration for devices with low hysteresis [4].  


[1]     W. Tress, N. Marinova, T. Moehl, S. M. Zakeeruddin, M. K. Nazeeruddin, M. Grätzel, Energy Environ. Sci., 2015, 8, 995.

[2]     D. W. deQuilettes, W. Zhang, V. M. Burlakov, D. J. Graham, T. Leijtens, A. Osherov, V. Bulovic, H. J. Snaith, D. S. Ginger, S. D. Stranks, Nature Comm., 2016, 7, 11683.

[3]     W. Nie, H. Tsai, R. Asadpour, J.-C. Blancon, A. J. Neukirch, G. Gupta, J. J. Crochet, M. Chhowalla, S. Tretiak, M. A. Alam, H.-L. Wang, A. D. Mohite, Science, 2015, 347, 522-525.

[4]     P. Calado, A. M. Telford, D. Bryant, X. Li, J. Nelson, B. C. O’Regan, P. R. F. Barnes, arXiv:1606.00818.

15.15 - 15.30 D2.O2 Padture, Nitin
Brown University

Amine-Gas Based Scalable Synthesis/Processing of High-Quality Hybrid-Perovskite Thin Films for Solar Cells

Nitin Padture*a, Yuanyuan Zhoua, Shuping Pangb, Kai Zhuc

a, Brown University, 184 Hope Street, Box D, Providence, RI 02912, USA
b, CAS Qingdao Institute for Bioenergy and Bioprocess Technology, 189 Songling Road, Laoshan District, Qingdao, 266101, P.R. China
c, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA

We have shown that MAPbI3 hybrid-perovskites when exposed to methylamine (CH3NH2) gas at room temperature ‘melt’ into a viscous liquid within seconds.[1] Most interestingly, when the CH3NH2 gas is removed, the MAPbI3 recrystallizes, with better crystallinity and texture, also within seconds.[1] This unprecedented phenomenon is used to ‘heal’ nominally prepared porous MAPbI3 thin films into dense, high-quality thin films over very large areas. Recently, we have also shown that porous inorganic thin films (HPbI3 and NH4PbI3) can be simultaneously ‘healed’ and transformed to dense, high-quality MAPbI3 thin films using the CH3NH2-gas treatment.[2,3] Most recently, we have shown that MAPbI3 thin films can be converted to ‘black’ α-FAPbI3 thin films, while preserving the original microstructure and morphology, when exposed to formamidine (HC(=NH)NH2) gas at 150 ˚C for a few minutes.[4] This is the result of a redox displacement reaction.[4] Thus, amine-gas based synthesis/processing of hybrid perovskite thin films offers unprecedented opportunities for exploring different chemistries and up-scaling. These unique phenomena, and our basic understanding of the underlying mechanisms, are discussed, together with the application of amine-gas based synthesis/processing of hybrid-perovskite thin films in large-area, high-performance solar cells.

[1] Angew. Chem., 54, 9702 (2015)

[2] J. Am. Chem. Soc., 138, 750 (2016)

[3] Angew. Chem., 55, 14723 (2016)

[4] J. Am. Chem. Soc., 138, 5535 (2016)

15.30 - 15.45 D2.O3 Aranda, Clara
Universitat Jaume I

Solvent Engineering for the Fabrication of High Efficiencies Perovskites Solar Cells in Ambient Conditions

Clara Arandaa, Antonio Guerrero*a

Universitat Jaume I, Avda. Sos Baynat s/n, Castelló, 12006, ES

Solvent Engineering for the Fabrication of High Efficiencies Perovskites Solar Cells in Ambient Conditions  


Clara Aranda1*, C. Cristóbal1, Antonio Guerrero1, Juan Bisquert1 


1 Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain 


The field of lead halide perovskites for solar cell applications has recently reported impressive power conversion (PCE) above 22 % using complex mixed cation formulations. Very importantly, highest PCE have been obtained using totally dry environmental conditions increasing the processing costs (i.e. use of glovebox). In this work devices processed in air under different relative humidity conditions are prepared with PCE approaching 19 % for the simplest lead halide perovskite (MAPbI3, MA= Methyl ammonium).1 Coordination chemistry during the crystallization process of perovskite films is the key parameter to obtain high quality devices.2 MAPbI3 free of chemical defects is generated through intramolecular exchange of the PbI2·DMSO adduct with MAI. In ambient conditions, water and DMSO compete to form the adduct due to the similar coordination capacity towards the Pb atom. Formulations not adequately balanced to account for humidity conditions and coordinating solvents (i.e. DMSO) lead to films with poor morphology. These films show negative multiiodide plumbate chemical defects which act as recombination centers reducing the photocurrent and Fill Factor in photovoltaic devices. This work demonstrates the possibility to fabricate high efficiency devices under high humidity conditions taking into account the importance between the amount of water and solvents. 




1. Clara Aranda, César Cristóbal, Leyla Shooshtari, Cheng Li, Sven Huettner, Antonio Guerrero, Sustainable Energy & Fuels, 2017, DOI: 10.1039/C6SE00077K 


2. Sara Rahimnejad, Alexander Kovalenko, Sergio Martí Forés, Clara Aranda and Antonio Guerrero, ChemPhysChem 2016, 17,1 – 5

15.45 - 16.00 D2.O4 Yasin, Amrita
Swansea University, Department of Materials Engineering

UV-vis fabrication of TiO2 compact and mesoporous layers in application to planar lead halide perovskite solar cells

Amrita Yasin*a, Anthony Lewisa, Eifion Jewella, Justin Searlea, James McGettricka, Cameron Pleydell-Pearcea, Paul Williamsa, Joel Troughtona, Chung Tsoia, Trystan Watsona, James Durrantb, David Worsleya, Peter Hollimana, Cecile Charbonneau*a

a, Swansea University, Department of Materials Engineering, Swansea University Bay Campus, Swansea, SA1 8EN, GB
b, Imperial College London, Department of Chemistry, Imperial College Rd, Kensington, London SW7 2AZ, GB

This work presents our latest research on low-temperature TiO2 nanoparticle synthesis followed by UV-vis processing of electron transport layers for planar lead halide perovskite solar cells. Crystalline anatase particles measuring 3-6 nm were synthesized via hydrolysis of TiCl4.THF at 90 °C, 20 minutes. Low concentrations oxalic acid is added to provide bidentate chemical bridging between the nanoparticles. An investigation is conducted into the optimum proportions of oxalic acid and isopropanol (used as a wetting agent) to yield homogeneous compact films via spraying and drop-casting. In order to form electron transport layers (ETLs) for planar lead halide perovskite solar cell, the solution is sprayed upon FTO glass at 120 °C and subjected to heat treatment at 250 °C and 550 °C, and UV-vis treatment for 3 seconds and 3 minutes. The results showed that UV treatment was effective in removing the oxalic acid and successful in creating crystalline compact layers of 50-100 nm thickness. Assembled devices reached device efficiencies up to 7%.

Following the success of low-temperature nanoscale anatase synthesis, we prepared mixed-phase anatase and rutile nanoparticles by varying the TiCl4.THF concentration and reaction times. The rutile particles serve as a scaffold with the surrounding anatase particles as a low-T ceramic glue to assist with the stabilisation of the films under UV processing.


16.00 - 16.30 Coffee break
Chair: Chun-Guey Wu
16.30 - 16.45 D2.O5 McKechnie, Scott
King's College London

Local field origin of dynamic Rashba splitting in perovskite solar cells

Scott McKechnie*a, Mark van Schilfgaardea, Pooya Azarhoosha, Jarvist Frostb, Aron Walshb

a, King's College London, Strand, London WC2R 2LS, UK, GB
b, Imperial College London, Kensington, London SW7 2AZ, GB

Perovskite solar cells have outstanding optoelectronic properties and have made unprecedented gains in power conversion efficiency. Although much progress has been made in understanding the fundamental device physics, there is uncertainty over the mechanism behind the slow bimolecular recombination rate. The slow recombination leads to remarkably long carrier lifetimes and, critically, minority carrier diffusion lengths greater than the film thickness required for complete absorption. In a recent study [1], we showed that in methyl-ammonium lead iodide, there is an interplay between the dynamically broken symmetry and the relativistic electronic structure. Lattice distortions produce internal electric fields that combine with large spin-orbit coupling to form a slightly indirect gap. The photoexcited carriers thermalise to offset points and the momentum mismatch suppresses recombination for small (solar) light fluences. This reciprocal space effect reduces the recombination rate by a factor of more than 350 compared to direct gap behaviour.

In this talk, we extend the analysis and show that the mechanism is also present in other halide perovskites, due to the octahedral distortions present at finite temperature. We explain the results in terms of the formation of dynamic local fields which we characterise with custom codes, and connect this back to the lattice response.

[1] P. Azarhoosh, S. McKechnie, J. M. Frost, A. Walsh and M. van Schilfgaarde, APL Mater. 4, 091501 (2016).

16.45 - 17.00 D2.O6 Shargaieva, Oleksandra
Helmholtz Zentrum Berlin

A novel cation for hybrid perovskite band gap tuning

Oleksandra Shargaieva*a, Felix Langa, Jörg Rappicha, Norbert Nickela

Helmholtz Zentrum Berlin, Kekulestr. 5, Berlin, 12489, DE

Since its emergence hybride perovskites have shown a huge potential as an absorber in solar cells leading to efficiencies above 22 %.1 Hybrid perovskites show high charge carrier mobilities, high absorption coefficients, and allow band gap tuning. These properties render hybrid perovskites a perfect material for tandem solar cells. For a perovskite – silicon tandem solar cell it was shown that the top perovskite solar-cell should have a band gap of about 1.7 – 1.8 eV to fully utilize the solar spectrum.2 Presently, the optimum band gap was achieved using mixed halide perovskites. However, most of the materials exhibit photo-instability that leads to a phase separation and consequently, an alteration of the band gap.

In this work, we present a new way of band gap tuning by addition of ethylenediammonium iodide (EDDI) in methylammonium lead iodide perovskite (MAPI). The samples were characterized using photoluminescence (PL), absorption and transmission, and X-ray spectroscopy. The obtained samples show a linear increase of the band gap energy from 1.6 to 1.78 eV with increasing content of EDDI. X-ray analysis of the samples shows that EDDI is completely incorporating into crystalline lattice of MAPI. Interestingly, the samples alloyed with EDDI undergo a transition to the cubic phase with increasing EDDI content. Also, the addition of EDDI shows a positive impact on morphology of the thin films in terms of an enhanced grain size. Finally, we demonstrate the influence of EDDI on the device performance of solar cells.


2 D.P. McMeekin, et al, Science (2016), 351 (6269), 151-15508

17.00 - 17.15 D2.O7 Wang, Feng

Stable FAPbI3 with Voc loss of 0.36 V in solar cell devices

Feng Wang*a, Ni Zhao*b

a, IFM, Linköpings universitet, Linköping, 581, Sweden
b, Electronic Engineering, The Chinese University of Hong Kong, New Territories, Hong Kong,, China

Recent advances in organolead halide perovskite solar cells have led to a remarkable improvement in the cell efficiency [1]. Yet, it is still challenging to achieve good moisture resistance of the perovskite films while obtaining high cell efficiency [2, 3, 4]. Here we address the issue through a simple post-deposition passivation treatment of perovskite films with small-sized amine molecules containing benzene rings [5]. We compared three structurally similar aromatic molecules, including aniline, benzylamine and phenethylamine, and observed a drastic difference in their passivation effect. Through density functional theory calculations we found that the efficacy of the moisture resistance and defect passivation is extremely sensitive to the steric arrangement of the amine molecules and that only benzylamine provides the optimal configuration. Solar cells based on benzylamine modified formamidinium lead iodide (FAPbI3) perovskite films exhibit a champion efficiency of 19.2% and an open-circuit voltage (Voc) of 1.12 V, revealing extremely low loss-in-potential (0.36 eV) in the cells. The modified FAPbI3 films exhibit no degradation in their structural and electronic properties after >2800 hours air exposure. The study elucidates the molecular passivation principles to achieve simultaneous efficiency and stability improvement.  


[1]    M. Saliba, T. Matsui and J. Y. Seo, Energy Environ. Sci., (2016), 9, 1989.

[2]    X. Li, M. I. Dar and C. Y. Yi, et al. Nat. Chem. (2015), 7, 703.

[3]    S. Yang, Y. Wang and P. Liu, et al. Nature Energy (2016), 1, 15016.

[4]    I. C. Smith, E. T. Hoke and D. Solis-Ibarra, et al. Angew. Chem. Int. Edit. (2014), 53, 11232;

[5]    F. Wang, W. Geng and Y. Zhou, et al. Adv. Mater. (2016), 28, 9986.

17.15 - 17.30 D2.O8 Moser, Jacques-E.
Institute of Chemical Sciences & Engineering, École Polytechnique Fédérale de Lausanne

Dynamics of Carrier Separation and Accumulation at Interfaces in Perovskite Thin-Film Solar Cells

Jacques-E. Moser*a, Marine E. F. Boudubana, Arun A. Paraecattila, Andrés Burgos Caminala, Joël Teuschera

Institute of Chemical Sciences & Engineering, École Polytechnique Fédérale de Lausanne, EPFL SB ISIC GR-MO, Station 6, Lausanne, 1015, CH

   Organo-lead trihalide perovskite solar cells (PSCs) belong to the family of electron donor-acceptor heterojunction systems, where photocarriers do not only need to be quickly transported across the light-absorbing semiconductor layer, but must also be injected efficiently into the respective charge-extracting contact materials.

   The origin of the performance inhomogeneity observed among PSCs of various compositions and architectures is unveiled by probing separately the dynamics of three essential processes: i) Carrier separation and transport across multigrain or homogeneous perovskite films, ii) Carrier trapping and recombination, and iii) Transmission of carriers through heterojunctions with hole- and electron specific materials.

   Field-induced dynamic phenomena, such as carrier separation and charge accumulation at interfaces were monitored in real time by use of time-resolved electroabsorption spectroscopy (TREAS). In combination with ultrafast optical pump-THz probe (OPTP) and femtosecond broadband fluorescence up-conversion (FLUPS) spectroscopies, this technique allowed to monitor the temporal evolution of the mobility of carriers and to unravel the mechanisms of charge trapping and recombination within the active layer.

   Transport and interfacial charge transfer problems that can occur in non-optimum PSC devices were diagnosed by application of TREAS. A significantly more efficient electron injection through the  (MA, FA)PbI3-xBrx | SnO2 interface was observed in particular, along with a decreased bulk recombination rate, compared to the standard MAPbI3 material.

   These results account for the reported higher open-circuit voltage and altogether better photovoltaic performance of solar cells based on planar, mixed organic cations, mixed halide perovskite semiconducting thin films.

17.30 - 19.00 Posters/Exhibition and wine
20.00 - 22.30 Social dinner
24th May 2017 - Day 3 (Wednesday)
General session G3
Chair: Michael Grätzel
9.00 - 9.45 G3.K1 Sargent, Edward
University of Toronto

Interfacing with perovskites

Edward Sargent*

University of Toronto, ECE 10 King's College Rd, Toronto, 0, CA

I will review recent progress in understanding how allied materials - including metal oxides, metal chalcogen quantum dots, and surface-terminating organics - interface with perovskites, and how these interfaces can best be exploited.


I will review recent progress in understanding how allied materials - including metal oxides, metal chalcogen quantum dots, and surface-terminating organics - interface with perovskites, and how these interfaces can best be exploited.


I will review recent progress in understanding how allied materials - including metal oxides, metal chalcogen quantum dots, and surface-terminating organics - interface with perovskites, and how these interfaces can best be exploited.


I will review recent progress in understanding how allied materials - including metal oxides, metal chalcogen quantum dots, and surface-terminating organics - interface with perovskites, and how these interfaces can best be exploited.



I will review recent progress in understanding how allied materials - including metal oxides, metal chalcogen quantum dots, and surface-terminating organics - interface with perovskites, and how these interfaces can best be exploited.

9.45 - 10.15 G3.I1 Petrozza, Annamaria
Center for Nano Science and Technology of Italian

Understanding the Physics of Defects in Metal-halide Perovskites for Optimizing Optoelectronic Devices

Annamaria Petrozza*

Center for Nano Science and Technology of Italian , via Pascoli 70/3, Milano, 20133, IT

Semiconducting metal-halide perovskites present various types of chemical interactions which give them a characteristic fluctuating structure sensitive to the operating conditions of the device, to which they adjust. This makes the control of structure-properties relationship, especially at interfaces where the device realizes its function, the crucial step in order to control devices operation. In particular, given their simple processability at relatively low temperature, one can expect an intrinsic level of structural/chemical disorder of the semiconductor which results in the formation of defects.Here I will review our understanding in the identification of key parameters which must be taken into consideration in order to evaluate the suscettibility of the perovkite crystals (2D and 3D) to the formation of defects, allowing one to proceed through a predictive synthetic procedure. I will discuss the role of defect physics in determing the open circuit voltage of metal halide perovskite solar cells and present technological strategies for the optimization of devices which include: 1) the engineering of the charge extracting layer (CEL), which accounts not only for the energy level alignment between the CELs and the perovskite, but also for the quality of the microstructure of the perovskite bulk film that is driven by the substrate surface; and 2) the use of inks based on colloidal suspensions of nanoparticles which lead to a high level of control over the material quality and device reliability, and offer more versatile processing routes by decoupling crystal growth from film formation.

10.15 - 10.45 G3.I2 Hanaya, Minoru
Division of Molecular Science, Graduate School of Science and Technology, Gunma University

Development of Dye-sensitized Solar Cells by using Silyl-anchor Dyes

Minoru Hanaya*

Division of Molecular Science, Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan

Dye-sensitized solar cells (DSSCs) have been actively investigated as a photovoltaic device as an alternative to conventional silicon-based inorganic solar cells, because of their potentially low production cost, low toxicity of the constituent elements and fine photovoltaic properties especially in low-light intensities and under scattered lights such as indoor conditions. Organosilicon compounds such as silanols and alkoxysilanes have high bonding ability to metal-oxide surfaces by forming Si–O–metal bonds. Thus, we have focused on the development of alkoxysilyl dyes (i.e. silyl-anchor dyes) as photosensitizers for DSSCs, and recently we succeeded in achieving over 12% conversion efficiency in the cell using a carbazole/alkyl-functionalized oligothiophene/alkoxysilyl-anchor dye of ADEKA-1 as the photosensitizer [1].

For further improvement in the efficiency, we examined co-sensitization of ADEKA-1 with widely developed carboxy-anchor dyes. The carboxy-anchor dye of LEG4 was revealed to work effectively as the collaborative sensitizer to ADEKA-1 through an electron-injection enhancement effect, and we succeeded in obtaining 14.3% conversion efficiency in the cell under one sun illumination with the optimized cobalt(III/II) complex redox electrolyte solution and the graphene-nanoplatelet counter electrode [2].

When considering the practical application of the DSSCs, the photovoltage is also an important photovoltaic property and the improvement of the photovoltage would extend the applicability of DSSCs. For a higher photovoltage, we newly designed and synthesized a coumarin/alkyl-functionalized oligothiophene/alkoxysilyl-anchor dye of ADEKA-3, and succeeded in obtaining the photovoltage higher than 1.4 V, by preparing Mg2+-doped anatase-TiO2 electrode with negatively shifted conduction-band edge than the anatase-TiO2 electrode, applying twofold metal-oxide surface modification to the Mg-doped TiO2 electrode by MgO and Al2O3 for preventing the back electron transfer from the electrode to the redox electrolyte, and adding water to the electrolyte solution of Br3/Br redox mediator with using the advantage of the durability of the alkoxysilyl-dye adsorbed electrodes to water [3].

The results are attributed essentially to the strong adsorption property of silyl-anchor dyes to the TiO2 electrode, and demonstrate the validity of them as photosensitizers for DSSCs.

[1] K. Kakiage, Y. Aoyama, T. Yano, T. Otsuka, T. Kyomen, M. Unno and M. Hanaya, Chem. Commun. 50, 6379 (2014). [2] K. Kakiage, Y. Aoyama, T. Yano, K. Oya, J. Fujisawa and M. Hanaya, Chem. Commun. 51, 15894 (2015). [3] K. Kakiage, H. Osada, Y. Aoyama, T. Yano, K. Oya, S. Iwamoto, J. Fujisawa and M. Hanaya, Sci. Rep., 6, 35888 (2016).

10.45 - 11.15 Coffee Break
Chair: Michael Grätzel
11.15 - 11.45 G3.I3 McGehee, Michael
Stanford University

Perovskite tandem solar cells with greater than 25 % efficiency and enhanced stability

Michael McGeheea, Kevin Bush*a, Axel Palmstrom*a, Zhengshan Yu*b, Mathieu Boccard*b, Tomas Leijtens*a, Rohit Prasanna*a, Rongrong Cheacharoen*a, Zachary Holman*b, Stacey Bent*a

a, Stanford University, 476 Lomita Mall, Stanford, 94305, US
b, Arizona State University, 650 East Tyler Mall, Tempe, 85287, US

We have deposited perovskite solar cells with a bandgap of 1.68 eV onto heterojunction silicon solar cells that by themselves have an efficiency of 21% to create a 1 square centimeter monolithic tandem solar cell with an efficiency of 25.3%. We have also made all-perovskite tandems using a new ABX3 perovskite composition containing a mixture of tin and lead on the B site that have greater than 20% efficiency. With solar cells packaged between two sheets of glass with rubber edge seals, we have passed the industry standard 1000 hour 85°C 85% humidity damp heat test as well as 200 cycles between 85°C and -40°C. One of the keys to obtaining high efficiency and stability was optimizing the composition of cesium and formamidinium on the A site and iodine and bromine on the X site. We will show how light -induced phase separation occurs when there is too much bromine in the films. Another crucial step towards improving stability is the use of atomic layer deposition to deposit a tin oxide buffer layer on the perovskite that enables the sputter deposition of an indium tin oxide transparent electrode. ITO is less reactive with perovskites than the metals that are typically used in perovskite solar cells. The ALD layer has minimal parasitic absorption and prevents shunting. Our progress towards achieving 30% power conversion efficiency and passing even more aggressive stability tests will be presented.

11.45 - 12.15 G3.I4 Wu, Chun-Guey
National Central University

The synergistic effect of H2O and DMF towards stable and 20% efficiency inverted perovskite solar cells

Chun-Guey Wu*

National Central University, 300th Jhong-Da road, Jhong-Li, 32001, TW

   High quality thick 500 nm CH3NH3PbI3 perovskite absorber with the horizontal grain size up to 3 mm and the lateral size equal to the film thickness was prepared by the synergistic effect of H2O additive and DMF vapor treatment. The inverted (p-i-n) cell based on this high-quality thick perovskite film achieves a high power conversion efficiency of 20.1%. The cell shows no current hysteresis and stable in the inert and ambient atmospheres. H2O helps MAI to penetrate into the thick PbI2 to form thick film with pure MAPbI3 phase and produce bigger gains by slow down the perovskite crystallization rate. It can also cooperate with DMF to control the dissolving of perovskite grains during DMF vapor post treatment. As a result, large multi-crystalline perovskite grains without observable hole and crease are formed when DMF and H2O were removed in the following heating. The synergistic effect of H2O and DMF was evidenced by SEM images and GIWXRD patterns taken simultaneously. This synergistic strategy for preparing high-quality, thick perovskite film was extended to fabricate large-area MAPbI3 film for the mini-module with the active area of 11.25 cm2 to realize the efficiency of more than 15%.

12.15 - 12.45 G3.I5 Tress, Wolfgang

Energy & Environmental Science Readers' Choice Lecture

Wolfgang Tress*

LPI, EPFL, 1015 Lausanne, CH

Solar cells based on lead halide perovskites have recently emerged showing a tremendous increase of power-conversion efficiency which exceeded 20 %. In this talk, the device physics of perovskite solar cells is addressed. The focus is on recombination of charge carriers because this process is ultimately limiting open-circuit voltage and fill factor in perovskite solar cells. Different architectures such as planar and mesoporous-TiO2 based devices are presented.

The origin of the open-circuit voltage is discussed based on the reciprocity relation between electroluminescence and photovoltaic quantum efficiency.1,2 Different recombination mechanisms (radiative, trap-mediated) are investigated and related to the device performance.

Hysteresis in the current-voltage curve is related to recombination as well. It is shown how different prebias voltages influence recombination rates.3 The results are explained by the mixed ionic and electronic conductivity of the material, where displaced ions change interface and defect recombination. A recently discovered inverted hysteresis and reversible photo-induced degradation mechanisms on the timescale of minutes to hours are put into the framework of ion migration as well.4

An outlook is given on strategies aiming for a further improvement of the open-circuit voltage.

[1] Tress, W. et al. Predicting the Open-Circuit Voltage of CH3NH3PbI3 Perovskite Solar Cells Using Electroluminescence and Photovoltaic Quantum Efficiency Spectra: the Role of Radiative and Non-Radiative Recombination. Adv. Energy Mater. 5, 140812 (2015).

[2] Bi, D. et al. Efficient luminescent solar cells based on tailored mixed-cation perovskites. Sci. Adv. 2, e1501170 (2016).

[3] Tress, W. et al. Understanding the rate-dependent J–V hysteresis, slow time component, and aging in CH3NH3PbI3 perovskite solar cells: the role of a compensated electric field. Energy Environ. Sci. 8, 995–1004 (2015).

[4] Tress, W. et al. Inverted Current–Voltage Hysteresis in Mixed Perovskite Solar Cells: Polarization, Energy Barriers, and Defect Recombination. Adv. Energy Mater. 6, 1600396 (2016). 

12.45 - 13.00 Sponsor talk: Metrohm Autolab
13.00 - 14.30 Lunch
Session A3
Chair: Monica Lira-Cantu
14.30 - 15.00 A3.IS1 Uchida, Satoshi
The University of Tokyo

The Evaluation of Capacitance for Perovskite Solar Cell with Hysteresis in I-V Curve

Ludmila Cojocaru*a, Satoshi Uchida*a, Piyankarage V. V. Jayaweerab, Shoji Kanekob, Jotaro Nakazakia, Takaya Kuboa, Hiroshi Segawa*a

a, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo, 153, JP
b, The Evaluation of Capacitance for Perovskite Solar Cell with Hysteresis in I-V Curve, Johoku 2-35-1, Naka-ku, Hamamatsu 432-8011, JP

For the efficient hybrid solar cells based on the organo-metal halide perovskites, real origin of the I-V hysteresis became a big issue and has been discussed widely. In this study, simulated I-V curves of different equivalent circuit models were validated with experimental I-V curves of a planar perovskite solar cell with the power conversion efficiency (PCE) of 18.0% and 8.8% on reverse respectively. We found that an equivalent circuit model with a series of double diodes, capacitors, shunt resistances, and single series resistance produces the simulate I-V curves with large hysteresis matching with the experimental observed curves. The electrical capacitances generated by defects due to the lattice mismatch at the TiO2/CH3NH3PbI3 and CH3NH3PbI3/spiro-OMeTAD interface are truly responsible for the hysteresis in the perovskite solar cells.

Additionally we directly observed the capacitance of the device by Stepped Light-induced Transient Measurements of Photocurrent and Voltage (SLIM-PCV) method.

Based on above experience and knowledge, we also examined to evaluate the cell performance at low light intensity condition.  Very surprisingly, due to the charge / discharge property with internal capacitance, we found the limitation to define the cell performance from the I-V curve because of the fake current.  To solve this issue, we newly propose the Maximum Power Point Tracking (MPPT) technique to define the most accurate cell performance of the hysteric device.

15.00 - 15.15 A3.O1 Petrus, Michiel
University of Munich (LMU)

The Influence of Water Vapor on the Stability and Processing of Hybrid Perovskite Solar Cells Made from Non-Stoichiometric Precursor Mixtures.

Michiel Petrus*a, Yinghong Hua, Davide Moiab, Philip Caladob, Aurelien Leguyb, Piers Barnesb, Pablo Docampoa

a, University of Munich (LMU), Butenandtstrasse 5-13, Munich, 81377, DE
b, Imperial college London, London, SW7 2AZ, UK

These days, the majority of groups agree that the most efficient perovskite photovoltaics are prepared using non-stoichiometric precursor mixtures. However, while several groups report that the best performance are obtained by using a PbI2 excess,[1] other groups reported that a methylammonium iodide (MAI) excess is required.[2] Also the effect of non-stoichiometric precursor mixtures on stability are contradicting. Some studies report that a PbI2-excess improves the stability,[3] while others have shown that this may be a “double-edged sword”, reducing the device lifetimes.[4] Here, we identify that these results can in fact be reconciled if exposure of the perovskite film to moisture is taken into account.

We investigated the influence of moisture on MAPbI3 films and solar cells derived from non-stoichiometric precursor mixtures.[5] We studied both the structural changes under controlled air humidity through in-situ X-ray diffraction experiments, and the electronic behavior of photovoltaic devices prepared from these perovskite films. A PbI2 excess was found to improve the performance and stability of the perovskite films compared to stoichiometric samples. We assign the decelerated degradation process either to excess PbI2 layers at the perovskite grain boundaries or to the termination of the perovskite crystals with Pb and I sites, which is in agreement with computational studies.[6] Both could act as barriers against the ingress of water molecules into the perovskite structure.

In contrast, an MAI excess in the precursor solution initially resulted in significantly smaller perovskite crystals and poor power conversion efficiency (PCE) values. Differential capacitance measurements indicate that the reduced performance could be attributed to a high density of trapping states and larger energetic disorder in MAI-rich regions at the grain boundaries. However, when these MAI-excess films were exposed to moist air (followed by a dehydration step), a striking improvement in PCE is observed. Our results reveal that MAI-excess films do initially not degrade upon exposure to humidity, but undergo a recrystallization process to form large, highly (110)-oriented crystals with fewer electronic defects. This leads to a remarkable improvement in photocurrent and PCE up to the level of devices derived from stoichiometric or PbI2-excess films.

In this presentation we will discuss these results and elaborate on the different degradation products which are formed depending on the precursor excess. Our results shed light on the role of moisture in the processing and degradation of perovskite films made from non-stoichiometric precursor solutions.       

[1] Nat. Energy, 2016, 1, 15017
[2] Nat. Energy., 2016, 1, 16081
[3] EES., 2015, 8, 3556
[4] JACS., 2016, 138, 10331
[5] ChemSusChem, 2016, 9, 2699
[6] Chem. Mater., 2015, 27, 4885

15.15 - 15.30 A3.O2 GROS, PHILIPPE C.
Lorraine University

From Ruthenium to Iron Complexes: The Challenging Chemical Tuning of Photophysical Properties


a, Lorraine University , SRSMC, Boulevard des Aiguillettes, Vandoeuvre-Les-Nancy, 54506, FR
b, Strasbourg University, IPCMS, Rue du Loess, 67200 Strasbourg , FR

The interest in organometallic complexes for optical applications is growing continuously. The development of such applications implies the careful design of metal complexes with appropriate photophysical properties to ensure efficient light harvesting based on strong and broadband molecular absorption or exciton generation in the condensed phase and excited state charge or energy transfer. Ruthenium polypyridine complexes have long been considered as lead compounds due to their ideal photophysical and geometrical properties. And used with success in Dye-sensitized Solar Cells (DSSCs) with efficiencies in the 9-12 % range. Our group has reported several new ruthenium complexes with improved absorption domains thanks to ligand tuning.[1] While ruthenium-based complexes have been widely investigated and used in many different lab scale applications it is a scarce metal. In contrast iron, belonging to the same group of the periodic table, is naturally abundant, of low cost and low toxicity and thus appears as an ideal substitute. However, the replacement of ruthenium by iron is extremely challenging since in Fe-pyridine complexes an ultrafast non-radiative deactivation of the 1,3MLCT states into the low-energy metal-centered quintuplet 5T2 make Fe-pyridine unexploitable for applications requiring higher free energies. Our group has reported new carbene-based ligands for the stabilization of the 3MLCT state in iron complexes. We have shown that several of our iron complexes can sensitize the TiO2 semiconductor in a laboratory DSSC, leading to measurable photocurrent and power conversion efficiency.[2] We have obtained the longest 3MLCT state ever reported for iron(II) complexes.[3,4]  The conference will present our works on the preparation of ruthenium and iron complexes with focus on the chemical tuning of electronic and photophysical properties as well as their applications in DSSCs.  

References [1] Gros, P.C. & Beley, M. (2014) Organometallics, 33 (18), 4590 [2] Duchanois, T.; Etienne, T.; Cebrián, C.; Liu, L.; Monari, A.; Beley, M.; Assfeld, X.; Haacke, S.& Gros, P. C. (2015) Eur. J. Inorg. Chem., 2469 [3] Liu, L., Duchanois, T., Etienne, T., Monari, A., Beley, M., Assfeld, X., Haacke, stefan, & Gros, P. C. (2016). Phys. Chem. Chem. Phys., 18, 12550 [4] Pastore, M.; Duchanois, T.; Liu, L.; Monari, A.; Assfeld, X.; Haacke, S. & Gros, P. C. (2016) Phys. Chem. Chem. Phys. 18, 28069

15.30 - 15.45 A3.O3 Pazoki, Meysam
uppsala university

The mechanism of ion migration, Photoinduced local electric fields and The Stark effect in Perovskite solar cells materials

Tomas Edvinsson*a, Gerrit Boschloob, Meysam Pazokia

a, uppsala university, Angstrom lab, department of solid state physics, uppsala, 75120, SE
b, uppsala university, Angstrom lab, department of physical chemistry, uppsala, 75120, SE

The Stark effect within the perovskite solar cell materials has been widely investigated in detail by photo induced absorption(PIS) spectroscopy in the films as well as the full devices with efficiencies above 20%. A pllausible mechanism has been proposed and supported by ground state, time dependent and nudge elastic band DFT calculations. The relations with local structural changes, titlting of the octahedra and device hysteresis has been studied for the cesium, metyl ammonium and formamidinium lead iodide perovskites. Electrochemical impedance spectroscopy and the photovoltage decay measurements are in line with the observed Stark effect in the devices suggesting an ion movement based hysteresis effect in the current voltage of the devices. Furthermore the dielectric response of the material to the local fields follow the dipole of the monovalent cation. A higher dipole have more interactions to the vacancy and higher response to the local electric fields.The presented experimental-theoretical results shed light to the photophysics and the mechanism of ion migration in the lead halide perovskite solar cell materials.

15.45 - 16.00 A3.O4 Paetzold, Ulrich
Institute of Microstructure Technology, Karlsruhe Institute of Technology

Perovskite/CIGS Thin-Film Solar Module Reaches Efficiency of 17.8%

Ulrich Paetzold*b, Manoj Jaysankara, Robert Gehlhaara, Erik Ahlswedec, Stefan Paetelc, Weiming Qiua, Joao Bastosa, Lucija Rakocevica, Bryce Richardsb, Tom Aernoutsa, Michael Powallac, Jef Poortmansa

b, Institute of Microstructure Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany, Eggenstein-Leopoldshafen, 76344, DE
c, Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg, Industriestr. 6, 70565 Stuttgart, Germany, DE
a, imec , Kapeldreef 75, 3001 Leuven, Belgium, BE
d, Light Technology Institute, Karlsruhe Institute of Technology, Engesserstraße 13, 76131 Karlsruhe, Germany,

Thin film perovskite/ CIGS multijunction solar modules, combining a semitransparent perovskite top solar module stacked on a CIGS bottom solar module, are a promising route to surpass the efficiency limits of single-junction thin-film solar modules. In this work, we present a scalable thin-film perovskite/CIGS photovoltaic module architecture with an area of 3.76 cm² and a power conversion efficiency of 17.8%. Our prototype outperforms both the record single-junction perovskite solar module of the same area as well as the reference CIGS solar module.

The presented perovskite/CIGS thin-film multijunction solar module makes use of the “4-terminal architecture”, which stacks the perovskite solar module in superstrate configuration on top of the CIGS solar module in substrate configuration. The demonstrated prototype employs the perovskite absorber material CH3NH3PbI3 that ideally absorbs all photons of the solar spectrum with energy higher than its bandgap (1.6eV). Furthermore, photons of energies lower than the bandgap of the perovskite are mostly transmitted to the CIGS solar module to be harvested, which has a bandgap around 1.15 eV. Both submodules apply a fully scalable interconnection scheme that can accommodate scale-up towards square meter scale thin-film multijunction solar modules.

In this work, we describe in detail the architecture of our prototype perovskite/CIGS multijunction solar module as well as the thin-film interconnection schemes of the perovskite top solar module and the CIGS bottom solar module. We compare the performance of the perovskite/CIGS multijunction solar module with the reference stand-alone perovskite and CIGS solar modules. In order to identify the future potential of the presented stacked perovskite/CIGS thin-film solar module, we quantify the various losses in the presented prototype and identify the key challenges of this technology towards highest power conversion efficiencies above 30%.

16.00 - 16.30 Coffee break
Chair: Monica Lira-Cantu
16.30 - 16.45 A3.O5 Hatton, Ross
Department of Chemistry, University of Warwick

Enhanced Stability and Efficiency in Tin Perovskite Photovoltaics

Kenneth Marshalla, Marc Walkerb, Richard Waltona, Ross Hatton*a

a, Department of Chemistry, University of Warwick, Library Road, Coventry, CV47AL, GB
b, Department of Physics, University of Warwick, Coventry, CV4 7AL, GB

Photovoltaics (PVs) based on tin halide perovskites have not yet benefitted from the same intensive research effort that has resulted in lead perovskite PVs achieving power conversion efficiencies of >20% after only 7 years of development, due to the susceptibility of tin perovskites to oxidation in air combined with the low energy of defect formation and the difficultly in forming films with a low density of pin-holes. This talk will describe (B)-γ CsSnI3 perovskite based PVs with a simplified device structure that exhibit a stability ~10 times greater than devices with the same architecture using methylammonium lead iodide perovskite, and a power conversion efficiency of 3.56% (the highest reported to date for a CsSnI3 perovskite PV device): Devices tested in air (humidity ~25%, temperature ~ 50 °C) without encapsulation and under 1 sun continuous simulated solar illumination retain ≥ 70% of their starting efficiency after ~ 7 hours, with the best performing devices taking 16 hours to reduce to the same value. The high device fill-factor is achieved using a strategy that removes the need for an electron blocking layer or an additional processing step to minimise the pinhole density in the perovskite film, which is based on co-depositing the perovskite precursors with SnCl2. The results of experiments that shed light on the reason for the improved performance and high tolerance to pin-holes will be presented. Taken together, the findings reported herein justify an intensive research effort into tin perovskite PVs, focused on improving the power convserion efficeincy to a level comparable to that of lead perovskite PVs.  

1. K. P. Marshall, M. Walker, R. I. Walton and R. A. Hatton, Nature Energy (2016), DOI:10.1038/nenergy.2016.178.

16.45 - 17.00 A3.O6 Robertson, Neil
University of Edinburgh

Lead-free Organic-inorganic Iodobismuthates for Photovoltaics

Neil Robertson*a, Tianyue Lia, Wenjun Wua, Carole Morrisona, Yue Hu*b, Hongwei Hanb

a, University of Edinburgh, Kings Buildings, David Brewster Road, Edinburgh EH93FJ, UK
b, Michael Grätzel Center for Mesoscopic Solar Cells, Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China

Perovskite solar cells (PSCs) have brought a paradigm shift in efficiencies of solution-processed photovoltaics, rising to around 22%. One potential problem with perovskite solar cells however, is the use of a soluble lead complex in the APbX3 absorber layer (A = e.g. CH3NH3, X = I, mixed I/Br, mixed I/Cl), leading to concerns around toxicity. Concerns over the leakage of lead and the improper disposal of cells may restrict application in certain areas. In addition, regulatory or perception issues may also restrict some applications, even where the toxicity is not itself a major factor. To address this potential limitation, non-toxic metal-halide photovoltaics are now being explored. 

A possible alternative is to use the non-toxic element bismuth, however the Bi(III) oxidation state will lead to different, non-perovskite, stoichiometries compared with Pb(II). Strategies are therefore required to achieve 3-dimensional charge transfer without the perovskite structure. We have explored ABiI4 absorbers featuring edge-sharing BiI6 octahedra forming a chain structure, with A = an aromatic anion. Short I…I and I…A contacts give rise to pseudo 3-dimensional structure. Our preliminary studies of these as absorbers in solar cells show working cells with efficiency that, although low at around 1%, [1] is comparable with the best among the other small number of Bi-halide materials studied so far. Furthermore, we have used for the first time with a bismuth-iodide absorber, the triple mesoscopic cell structure [2], which is fully printable, stable and scalable.  

We will report on the design, synthesis and characterization of several new bismuth-iodide absorbers, including successful strategies to lower the bandgap, and the resulting solar cell performance in triple-mesoscopic cells. 

References:[1] Tianyue Li, Yue Hu, Carole A. Morrison, Wenjun Wu, Hongwei Han, Neil Robertson, Lead-free Pseudo-three-dimensional Organic-inorganic Iodobismuthates for Photovoltaic Applications, Sustainable Energy and Fuels, 2017, DOI: 10.1039/C6SE00061D[2] A. Mei, X. Li, L. Liu, Z. Ku, T. Liu, Y. Rong, M. Xu, M. Hu, J. Chen, Y. Yang, M. Grätzel and H. Han, Science, 2014, 345, 295–298

17.00 - 17.15 A3.O7 Li, Mingjie
School of Physical and Mathematical Sciences, Nanyang Technological University

Slow carrier thermalization and highly efficient hot-carrier extraction from lead halide perovskite nanocrystals

Mingjie Lia, Saikat Bhaumikb, Teck Wee Goha, Muduli Subas Kumarb, Natalia Yantarab, Michael Grätzelb, c, Subodh Mhaisalkarb, d, Nripan Mathewsb, d, Tze Chien Sum*a

a, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
b, Energy Research Institute @ NTU (ERI@N), Research Techno Plaza, X-Frontier Block, Level 5, Singapore 637553, Singapore
c, Laboratory of Photonics and Interfaces, Department of Chemistry and Chemical Engineering, Swiss Federal Institute of Technology, Station 6, CH-1015 Lausanne, Switzerland, Switzerland
d, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore

Thermodynamic calculations revealed that single junction solar cell conversion efficiencies can exceed the Schottky-Queisser limits and reach around 66% under 1-sun illumination if the excess energy of hot photogenerated carriers is utilized before they cool down to the lattice temperature (i.e., hot-carrier solar cells).[1] Organic–inorganic lead halide perovskite semiconductors have recently emerged as the leading contender in low-cost high-performance solar cells.[2,3] Recent observations of a hot-phonon bottleneck effect in CH3NH3PbI3 thin films suggest that lead halide perovskites are also promising candidates for developing hot-carrier solar cells.[4] The key for the realization of hot-carrier solar cell include the slow hot-carrier cooling and effective extraction of hot-carrier energies which requires fast hot-carrier injection into charge collection layer before hot-carrier cooling down to the lattice temperature. Emulating semiconductor nanoscience, some interesting questions would be if the hot-carrier cooling rate in halide perovskites could be further modulated through confinement effects, and if these hot-carriers can be efficiently extracted. Here, the hot-carrier cooling dynamics and mechanisms in colloidal CH3NH3PbBr3 nanocrystals of different sizes (with mean radius ~2.5–5.6 nm) and their bulk-film counterpart were compared using room-temperature transient absorption spectroscopy. Our results revealed that the weakly quantum confined CH3NH3PbBr3 nanocrystals are very promising hot-carrier absorber materials(~ 2 orders slower hot-carrier cooling times and around 4 times larger hot-carrier temperatures than their bulk-film counterparts). This is attributed to their intrinsic phonon bottleneck and Auger-heating effects at low and high carrier densities, respectively. Importantly, we demonstrate efficient room temperature hot-electrons extraction (up to about 83%) by an energy-selective electron acceptor layer within ~1 ps from surface-treated perovskite nanocrystal films. These insights enable fresh approaches for extremely-thin-absorber and concentrator-type hot-carrier solar cells.[5] 


[1] Ross, R.T. & Nozik, A.J. Efficiency of Hot-Carrier Solar-Energy Converters. J. Appl. Phys. 53, 3813-3818 (1982).

[2] Lee, M.M., Teuscher, J., Miyasaka, T., Murakami, T.N. & Snaith, H.J. Efficient Hybrid Solar Cells Based on Meso-Superstructured Organometal Halide Perovskites. Science 338, 643-647 (2012).

[3] Zhou, H.P. et al. Interface engineering of highly efficient perovskite solar cells. Science 345, 542-546 (2014).

[4] Yang, Y. et al. Observation of a hot-phonon bottleneck in lead-iodide perovskites. Nat. Photonics 10, 53-59 (2016).

[5] Li, M. et al. Slow cooling and highly efficient extraction of hot carriers in colloidal perovskite nanocrystals. Nat. Commun. 8, 14350 doi: 10.1038/ncomms14350 (2017).

17.15 - 17.30 A3.O8 Wang, Shufeng
Peking University

The intrinsic photoproducts in organolead trihalide perovskite

Shufeng Wang*

Peking University, Rm N352, Phys Bldg, Peking University, Beijing, 100871, CN

The highly efficient organolead trihalide perovskite based solar cells are the top interests in photovoltaics for the recent years. It is well known that their high efficiencies benefit from the rich photo-induced free carriers. It is also know that excitons co-exist with the free carriers. Are these two photoproducts has a fixed ratio after excitation, or they are of dynamic balance depending on the density? This fundamental question decides whether the exciton can convert to free carriers to improve the cell efficiency. It also decides the excited state dynamics since the ratio follows the total density, which decays in time. In addition, the dynamic balance of exciton and free carriers should be a very general question in many widely studied semiconductors. However, no method can be applied to see such density-dependent behavior until now. We developed a density-resolved spectroscopic method to directly observe the photoproduct types and their density-dependent interconversion.

In perovskite, the dynamic co-existence of excitons and free carriers wasexperimentally verified for the first time. It is also revealed a exciton binding energy of 24±2 meV and an effective mass of electron-hole pair. (Ref: Physical Review B 94, 140302 (2016)). Surprisingly, with the method, a further study discoverd that the photoproduct system could be more complicated than above exciton-carrier system. It also indicates an internal subgrain morphology within the crystal grain, which had not been discussed before. Our spectroscopic method and the results are key findings to enrich the understanding of the photophysics in perovskite materials for photovoltaic applications. In addition, our method can be widely applied to other semiconductors.

Session B3
Chair: Nam-Gyu Park
14.30 - 15.00 B3.IS1 Freitag, Marina
Uppsala University

Copper Complexes for Dye-sensitized Solar Cells

Marina Freitag*a, Yasemin Saygilib, Yiming Caoc, Paul Liskac, Michael Grätzel*c, Anders Hagfeldt*b

a, Uppsala University, Ångström Laboratory, Uppsala, 75120, SE
b, EPFL, LSPM, 1015 Lausanne, CH, CH
c, EPFL, LPI, 1015 Lausanne, CH, CH

Most of the Dye-sensitized Solar Cell (DSC) research has focused on the introduction of new dyes disregarding the redox mediator or the hole transport material. Nevertheless, the next breakthrough in improved efficiency of DSCs will come from adjusting the driving force for regeneration of the oxidized dye and moving towards a solid state system.1,2 Recently copper bipyridyl complexes Cu(dmby)2 (0.97 V vs SHE), Cu(tmby)(0.87 V vs SHE) and Cu(dmp)2 (0.94 V vs SHE) showed impressive solar-to-electrical power conversion efficiencies of 10.3% 10.0% and 10.3%, respectively, using liquid electrolyte and the organic Y123 dye under 1000 W m-2 AM1.5G illumination. In particular, the high photovoltages of over 1.0 V were achieved by the whole series of copper complex based redox mediators without compromising photocurrent densities and despite small driving forces of 0.1 V to 0.2 V for dye regeneration.3   The use of copper complexes also leads to a breakthrough in the indoor light-harvesting. We developed a DSCs with liquid electrolyte or solid HTM, which advances over other photovoltaic technologies, including GaAs thin film solar cells, in terms of efficiency and cost under the ambient and diffuse light conditions. As a practical result, we show that the performance of copper complex based DSCs in an indoor environment results is 15% larger power output than of a GaAs thin film solar cell, which so far had the best performance under low light conditions. These characteristics will enable various indoor and diffuse light applications of DSC as useful power sources in the energy harvesting field.  

1. Freitag, M.; Daniel, Q.; Pazoki, M.; Sveinbjornsson, K.; Zhang, J.; Sun, L.; Hagfeldt, A.; Boschloo, G. Energy Environ. Sci., 2015,8, 2634-2637.

2. Freitag, M.; Giordano, F.; Yang, W.; Pazoki, M.; Hao, Y.; Zietz, B.; Grätzel, M.; Hagfeldt, A.; Boschloo, G. J. Phys. Chem. C 2016, 120 (18), 9595.

3. Saygili, Y.; Söderberg, M.; Pellet, N.; Giordano, F.; Cao, Y.; Munoz-Garcia, A. B.; Zakeeruddin, S. M.; Vlachopoulos, N.; Pavone, M.; Boschloo, G.; Kavan, L.; Moser, J.-E.; Grätzel, M.; Hagfeldt, A.; Freitag, M. J. Am. Chem. Soc. 2016.

15.00 - 15.15 B3.O1 Nafradi, B.

Optically switched magnetism in photovoltaic perovskite CH3NH3(Mn:Pb)I3

B. Nafradi*a, P. Szirmaia, M. Spinaa, H. Leeb, O.V. Yazyevb, A Arakcheevaa, D. Chernyshovc, M. Gibertd, L. Forroa, E. Horvatha

a, EPFL, EPFL SB IPHYS LPMC , Lausanne, 1015, CH
b, EPFL, EPFL SB IPHYS C3MP, Lausanne, ch
c, Swiss-Norwegian Beam Lines, European Synchrotron Radiation Facility, , 71 Avenue des Martyrs, F-38043 Grenoble Cedex 9,, France
d, DQMP—University of Geneva, 24 Quai Ernest Ansermet, CH-1211 Geneva, CH

The demand for ever-increasing density of information storage and speed of manipulation boosts an intense search for new magnetic materials and novel ways of controlling the magnetic bit. Here, we report the synthesis of a ferromagnetic photovoltaic CH3NH3(Mn:Pb)I3 material in which the photo-excited electrons rapidly melt the local magnetic order through the Ruderman–Kittel–Kasuya–Yosida interactions without heating up the spin system. Our finding the observed optical melting of magnetism could be of practical importance, for example, in a magnetic thin film of a hard drive, where a small magnetic guide field will trigger a switching of the ferromagnetic moment into the opposite state via the light-induced magnetization melting. This kind of ferromagnetic moment reversal is rapid and represents several indisputable advantages over other optical means of manipulation of the magnetic state reported earlier. It does not require high-power or femtosecond laser instrumentation, which, besides the complexity of the techniques, raises the stability issue due to photochemistry and fatigue coming from the high intensity and the rapid local thermal cycling of the material. Our method needs only a low-power visible light source, providing isothermal switching, and a small magnetic guide-field to overcompensate the stray field of neighbouring bits. Although this is a simple and elegant method for magnetic data storage, it has never been discussed in literature, because magnetic photovoltaic materials have not been developed. It should be emphasized that this mechanism is radically different from switching the orientation of magnetic domains–here the photoelectrons tune the local interaction between magnetic moments and thus change the magnetic ground state. This study provides the basis for the development of a new generation of magneto-optical data storage devices where the advantages of magnetic storage (long-term stability, high data density, non-volatile operation and re-writability) can be combined by the fast operation of optical addressing. Last but not least, this study highlights that besides photovoltaics, lasing and LED operation there is one more extraordinary feature of the CH3NH3PbI3 perovskite material.

15.15 - 15.30 B3.O2 Liao, Yuqin
Shanghaitech University

Highly-oriented low-dimensional tin halide perovskites with enhanced stability and photovoltaic performance

Yuqin Liaoa, Zhijun Ning*a

Shanghaitech University, School of Physical Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai, 201210, CN

The low toxicity and ideal band structure make tin (Sn) perovskite an attractive alternative to lead (Pb) perovskite for solar cells. The development of Sn perovskite solar cells, however, was impeded by the extremely poor stability when exposed to oxygen. Inspired by density function simulation, we explored low-dimensional Sn perovskite to enhance the oxidation resistance capability. In addition, the careful manipulation of the film composition enables oriented growth of perovskite perpendicular to the substrate, giving rise to compact perovskite film without pin holes. This is helpful to protect Sn2+ from contact with oxygen as well. For low dimensional film, the ubiquitous tin oxidation was effectively prevented, in comparison to their 3D counterpart. We subsequently explored this highly oriented low-dimensional Sn perovskite film for solar cells. The perpendicular growth of the perovskite domains between electrodes allows efficient carriers transportation, achieving power conversion efficiency of 5.94%, with an open circuit voltage (Voc) of 0.59 V, a short-circuit current density (Jsc) of 14.44 mA cm-2, and fill factor (FF) of 69%. These findings raise the prospect of pure Sn perovskite for solar cells application.

15.30 - 15.45 B3.O3 Tan, Hairen
Department of Electrical and Computer Engineering, University of Toronto

Efficient and stable sol-processed planar perovskite solar cells via contact passivation

Hairen Tan*a, Ankit Jaina, Oleksandr Voznyya, Edward Sargent*a

Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, M5S 3G4, CA

Metal halide perovskite solar cells have attracted extensive research interest for next-generation solution-processed photovoltaic devices because of their high solar-to-electric power conversion efficiency (PCE) and low fabrication cost. The top-performing PSCs, which have reached a certified PCE of 22.1%, have relied on high-temperature-sintered (450oC to 550oC) mesoporous TiO2 as electron-selective layer. Planar perovskite solar cells made entirely via solution-processing at low temperatures (<150oC) offer promise for simple manufacturing, compatibility with flexible substrates, and perovskite-based tandem devices; however, they require an electron-selective layer that performs well with similar processing. Here, we will report a contact passivation strategy using halide-capped TiO2 colloidal nanocrystal (NC) film as the electron-selective layer that mitigates interfacial recombination and improves interface binding in low-temperature planar solar cells. We fabricated solar cells with certified efficiencies of 20.1% and 19.5% for active areas of 0.049 and 1.1 square centimeters, respectively, achieved via low-temperature solution processing. Solar cells with an initial efficiency >20% retained 90% (97% after dark recovery) of their initial performance after 500 hours continuous room-temperature operation at their maximum power point under one-sun illumination. 

15.45 - 16.00 B3.O4 Dahlström, Staffan
Åbo Akademi University

Unintentional Bulk Doping of Polymer-Fullerene Blends from a Thin Interfacial Layer of MoO3

Staffan Dahlström*a, Mathias Nyman*a, Oskar J. Sandberg*a, Ronald Österbacka*a

Åbo Akademi University, Porthansgatan 3, Turku, 20500, FI

Optimization of the contacts using charge selective interlayers is of crucial importance for the device performance of low mobility solar cell devices such as organic bulk-heterojunction cells. A very commonly used anode interlayer is the high work function transition metal oxide molybdenum trioxide (MoO3). In this work we show that a thin interlayer of MoO3 causes unintentional bulk doping in polymer and polymer:fullerene  solar cells1. The unintentional bulk doping is identified by measuring doping profiles using the doping-induced capacitive regime of Charge Extraction by a Linearly Increasing Voltage (doping-CELIV)2. Our results show that the doping concentration is increasing towards the anode interlayer and the doping concentration is larger than 1016 cm-3 in the active layer film several hundreds of nanometers from the anode. Reference devices without a MoO3 interlayer are undoped. This kind of moderate doping is detrimental for device performance in the case of an active layer thickness larger than 100 nm. Time-of-Flight Secondary Ion Mass Spectrometry measurements, where molybdenum is detected on the surface of films with a MoO3 interlayer beneath the active layer, verifies that doping is caused by diffusion of MoO3 molecules from the interlayer through the active layer.


[1] M. Nyman, S. Dahlström, O. J. Sandberg, R. Österbacka, Adv. Energy Mater. 2016, 6, 1600670

[2] O. J. Sandberg, M. Nyman, R. Österbacka, Org. Electron. 2014, 15, 3413

16.00 - 16.30 Coffee break
Chair: Nam-Gyu Park
16.30 - 16.45 B3.O5 Saliba, Michael
École Polytechnique Fédérale de Lausanne

Highly Stable and Efficient Perovskite Solar Cells Via Multication Engineering

Michael Saliba*

École Polytechnique Fédérale de Lausanne, Station 6, Lausanne, 1015, CH

Perovskites have emerged as low-cost, high efficiency photovoltaics with certified efficiencies of 22.1% approaching already established technologies. The perovskites used for solar cells have an ABX3 structure where the cation A is methylammonium (MA), formamidinium (FA), or cesium (Cs); the metal B is Pb or Sn; and the halide X is Cl, Br or I. Unfortunately, single-cation perovskites often suffer from phase, temperature or humidity instabilities. This is particularly noteworthy for CsPbX3 and FAPbX3 which are stable at room temperature as a photoinactive “yellow phase” instead of the more desired photoactive “black phase” that is only stable at higher temperatures. Moreover, apart from phase stability, operating perovskite solar cells (PSCs) at elevated temperatures (of 85 °C) is required for passing industrial norms.

Recently, double-cation perovskites (using MA, FA or Cs, FA) were shown to have a stable “black phase” at room temperature.(1,2) These perovskites also exhibit unexpected, novel properties. For example, Cs/FA mixtures supress halide segregation enabling band gaps for perovskite/silicon or perovskite/perovskite tandems.(3) In general, adding more components increases entropy that can stabilize unstable materials (such as the “yellow phase” of FAPbI3 that can be avoided using the also unstable CsPbI3). Here, we take the mixing approach further to investigate triple cation (with Cs, MA, FA) perovskites resulting in significantly improved reproducibality and stability.(4) We then use multiple cation engineering as a strategy to integrate the seemingly too small rubidium (Rb) (that never shows a black phase as a single-cation perovskite) to study novel multication perovskites.(5)

One composition containing Rb, Cs, MA and FA resulted in a stabilized efficiency of 21.6% and an electroluminescence of 3.8%. The Voc of 1.24 V at a band gap of 1.63 eV leads to a very small loss-in-potential of 0.39 V, one of the lowest measured on any PV material indicating the almost recombination-free nature of the novel compound. Polymer-coated cells maintained 95% of their initial performance at 85°C for 500 hours under full illumination and maximum power point tracking. This is a crucial step towards industrialisation of perovskite solar cells.

(1) Jeon et al. Nature (2015)

(2) Lee et al. Advanced Energy Materials (2015)

(3) McMeekin et al. Science (2016)

(4) Saliba et al., Cesium-containing triple cation perovskite solar cells: improved stability, reproducibility and high efficiency. Energy & Environmental Science (2016)

(5) Saliba et al., Incorporation of rubidium cations into perovskite solar cells improves photovoltaic performance. Science (2016).




16.45 - 17.00 B3.O6 Glinka, Adam
Faculty of Physics, Adam Mickiewicz University in Poznan

Effects of post-assembly molecular and atomic passivation of sensitized titania surface – dynamics of electron transfer measured from femtoseconds to seconds.

Adam Glinkaa, Mateusz Gierszewskia, Iwona Grądzkaa, Błażej Gierczykb, Mariusz Jancelewiczc, Marcin Ziółek*a

a, Faculty of Physics, Adam Mickiewicz University in Poznan, Umultowska 85, Poznań, 61-614, PL
b, Faculty of Chemistry, Adam Mickiewicz University in Poznan, Umultowska 89b, Poznań, 61-614, PL
c, NanoBioMedical Centre, Adam Mickiewicz University in Poznan, Umultowska 85, Poznań, 61-614, PL

Unwanted recombination at the interfaces between titania, dye and hole transporting medium is one of the key problems in the development of dye-sensitized solar cells (DSSC) and photoelectrochemical cells for water splitting. Recently, novel approaches have been proposed based on surface passivation AFTER dye-sensitization process:  hierarchical molecular multi capping [1] and atomic layer deposition (ALD) of blocking coating [2]. We have investigated the impact of such methods on the dynamics of electron transfer at the dye-titania and titania-electrolyte interfaces using time resolved spectroscopic methods (femtosecond transient absorption and electrochemical impedance spectroscopy) applied to complete DSSC samples with cobalt-based electrolyte and champion ADEKA-1 dye (with silyl-anchor unit, record efficiency of 14 % [3]) or its popular carboxyl-anchor analogue, MK-2 dye [4].

Both hierarchical multi-capping and deposited blocking layers of alumina slowed down electron recombination between titania and electrolyte, occurring on millisecond time scale, significantly improving fill factor and open circuit voltage of the cells. On the other hand, the relative photocurrent of the cells (short circuit current per number of absorbed photons) was reduced upon both treatments, with a decrease higher for increasing alumina thickness (0.1-0.5 nm).

Similarly as in our previous studies of DSSC [4-5] the amplitude of the relative photocurrent was found to depend almost exclusively on the ultrafast and fast processes taking place in the first nanoseconds after dye excitation. Both molecular capping and atomic blocking layers slowed down electron injection process (from sub-ps to single ps average time constant) and partial back electron transfer occurring on the time scale of tens and hundreds of picoseconds. However, simultaneously with slowing back electron transfer, its contribution increased, decreasing the relative photocurrent. We interpret the results taking into account dye relaxation, existence of intermediate dye-titania charge transfer complex, and charge transfer processes occurring “through space” rather than through dye anchoring unit [6]. The importance of such processes on the efficiency of DSSCs has not been widely realized so far. 


This work was supported by NCN (National Science Centre, Poland) under project 2015/18/E/ST4/00196. 

[1] K. Kakiage et al., Chem. Commun. 50 (2014) 6379-6381.

[2] D. H. Kim et al., Adv. Mater. Interfaces (2016) 1600354

[3] K. Kakiage at al, Chem. Commun. 51 (2015) 15894-15897.

[4] J. Sobuś et al., ChemSusChem 8 (2015) 3118-3128.

[5] J. Sobuś, et al., Chem. Eur. J. 22 (2016) 15807-15818.

[6] S. Ye et al., J. Phys. Chem. C 117 (2013) 6066-6080. 

17.00 - 17.15 B3.O7 Sherkar, Tejas S.
Zernike Institute for Advanced Materials, University of Groningen

Recombination in Perovskite Solar Cells: Significance of Grain Boundaries, Interface Traps and Defect Ions

Tejas S. Sherkar*a, Cristina Momblonab, Lidon Gil-Escrigb, Enrico Bandiellob, Michele Sessolob, Henk J. Bolinkb, L. Jan Anton Kostera

a, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747, The Netherlands
b, Instituto de Ciencia Molecular, Universidad de Valencia, C/ Catedrático J. Beltrán 2, Paterna 46980, Spain

Trap-assisted recombination is the dominant recombination mechanism in perovskite solar cells (PSCs) and limits the efficiency of existing devices. We investigate the attributes of the primary trap-assisted recombination channels (grain boundaries and interfaces) and their correlation to defect ions in PSCs. We achieve this by using a validated device model to fit the simulations to the experimental data of efficient vacuum deposited p-i-n and n-i-p CH3NH3PbI3 solar cells including the light intensity dependence of open-circuit voltage and fill factor. We find that despite the presence of traps at interfaces and grain boundaries (GBs), their neutral (when filled with photo-generated charges) disposition along with the long-lived nature of holes leads to the high performance of PSCs. The sign of traps (when filled) is of little importance in efficient solar cells with compact morphologies (fused GBs, low trap density). On the other hand, solar cells with non-compact morphologies (open GBs, high trap density) are sensitive to the sign of the traps and hence cell preparation methods. Even in the presence of traps at GBs in the perovskite bulk, trap-assisted recombination at interfaces (HTL/perovskite and perovskite/ETL) is the dominant loss mechanism. We find a direct correlation between density of traps, density of mobile defect ions and the degree of hysteresis observed in the current-voltage (J-V) characteristics. Presence of defect states or mobile ions not only limits the device performance but also plays a role in the J-V hysteresis. We are able to give an estimate of the moving ions in these perovskite solar cells i.e. 1015 cm-3 at the most.

17.15 - 17.30 B3.O8 Stranks, Samuel
Research Laboratory of Electronics, Massachusetts Institute of Technology

Metal Halide Perovskite Polycrystalline Films Exhibiting Properties of Single Crystals

Roberto Brenesa, Dengyang Guob, Anna Osherova, Nakita Noelc, Christopher Eamesd, Eline Hutterb, Sandeep Pathaka, d, Farnaz Nirouia, Richard Friende, Saiful Islamd, Henry Snaithc, Tom Savenijeb, Vladimir Bulovica, Samuel Stranks*a, e

a, Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, 02139, US
b, Department of Chemical Engineering, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, NL
c, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU, GB
d, Department of Chemistry, University of Bath, Bath, BA2 7AY, GB
e, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, 0, GB

Metal halide perovskites have many of the attributes desirable for photovoltaic applications. Despite impressive device performance, polycrystalline perovskite films are still far from their full potential. Perovskite single crystals have superior properties to polycrystalline thin films including 2-4 orders of magnitude lower trap densities. However, controlled growth of single crystals into devices does not lend itself to the many advantages offered by solution-processing polycrystalline thin films, such as low-cost, scalable roll-to-roll depositions. Here, we perform in-situ micro-photoluminescence (PL) measurements on MAPbI3 films while immersing them for short periods with different atmospheric treatments. We find substantial light-soaking enhancements which are most prominent in the presence of both oxygen and moisture. Remarkably, the optimal treatments increase the internal PL quantum efficiency from ~10% to ~90%, as well as substantially enhance the emission spatial uniformity and stability. Time-resolved microwave conductivity measurements further reveal that the quality of the treated thin films resembles those of single crystals, with charge carrier mobilities of ~60 cm2/V/s and lifetimes >20 µs under solar illumination conditions. We propose a mechanism in which light redistributes ions and atmospheric exposure forms thin passivating lead iodide shells. This work decouples the effects of each of light and atmosphere, leading to a scalable post-treatment capable of producing films with optoelectronic properties akin to those of single crystals.

Session C3
Chair: Udo Bach
14.30 - 15.00 C3.IS1 Bach, Udo
Monash University

Work-Function Tuning for Perovskite Solar Cells

Xiongfeng Lin*a, Askhat Jumabekov*b, Udo Bacha

a, Monash University, Department of Materials Engineering, Clayton, 3800, AU
b, CSIRO, CSIRO Manufacturing, AU

Hybrid organic-inorganic metal halide perovskites are low-cost solution-processable solar cell materials with photovoltaic properties that rival those of conventional silicon. Thin layers of organic or inorganic charge transport materials (CTMs) typically accomplish efficient extraction of photogenerated charges from these perovskite films. These CTMs are typically chosen based on their workfunctions and their alignment with the conduction and valence band edges of the perovskite. The bandgap of metal halide perovskites used in PSCs is highly tunable, making these materials particularly interesting for multi-junction solar cell applications. The tunability on the other hand also brings about serious challenges in respect to the identification of appropriate contact materials, as even to date their choice is rather limited. Here we will introduce a new approach based on the work-function tuning of the charge extraction layer by means of a self-assembled molecular monolayer (SAM). We apply this concept to back-contact PSCs and provide evidence of the successful workfunction tuning by means of Kelvin probe microscopy while also presenting the photovoltaic performance date of these devices. We show that the presence of these SAMs can produce photovoltages of up to 600 mV and photocurrents in excess of 12 mA/cm2 under simulated sunlight, despite a large center-to-center electrode spacing of 6.5 µm.

15.00 - 15.15 C3.O1 Turkevych, Ivan
Central Chemical Research Base (CEREBA)

Quasi-Perovskite Solar Cells based on Iodobismuthates with Rudorffite Structure

Ivan Turkevych*a, Said Kazaouib, Eisuke Itoa, Toshiyuki Uranoa, Koji Yamadac, Hideo Yamagishia, Hiroshi Tomiyasua, Shinji Aramakia

a, Central Chemical Research Base (CEREBA), Higashi 1-1-1, AIST Central 5-2, Tsukuba, 3058565, Japan
b, Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology, Higashi 1-1-1, AIST Central 5-2, Tsukuba, 3058565, Japan
c, Department of Applied Molecular Chemistry, Nihon University, , Izumi-cho 1-2-1, Narashino, Chiba 275-8575, Japan

Lead halide perovskites have emerged as highly promising photovoltaic (PV) materials that have demonstrated remarkable PCE of 22% in single-junction cells. The efficiency limit of perovskite cells is ~31% that is close to the Shockley-Queisser limit. A strong disadvantage of the Pb-PVS is high toxicity of Pb. Although Sn and Ge also form halide perovskite structures, they are extremely unstable due to easy oxidation from divalent to tetravalent state. Other divalent metal cations cannot form a three-dimensional perovskite lattice, because they are too small to satisfy the Goldschmidt tolerance rule. Combination of monovalent and trivalent cations can result in the formation of C2ABX6 double-perovskites (C=Cs, CH3NH3; A=Ag, Cu; B=Bi, Sb; X=Br, I) with alternating corner shared AX6 and BX6 octahedral units, though their bandgap is >2 eV and indirect. Recent exploration of photovoltaic C3B2X9 halides consisting of isolated face-shared B2X9 bioctahedral units revealed interesting similarities to C2SnX6 anti-fluorites consisting of isolated SnX6 of tetravalent Sn. Both structural motifs lead to semiconducting materials with poor transport properties. In contrast to the above mentioned structures with corner- and face-shared octahedral units, we explored another family of photovoltaic halides based on edge-shared AX6 and BX6 units with the general formula of AaBbXx, where A=Ag, Cu; B=Bi, Sb; X=Br, I, and x=a+3b. As perovskites were named after Lev Perovski according to their prototype oxide CaTiO3, we propose to name these new AaBbXx halides as "rudorffites" according to their prototype oxide NaVO2 that was discovered by Walter von Rudorff in 1954. The crystal structure of rudorffites belongs to R-3m crystallographic group, where the cation sublattice can be described as joint populations of monovalent (A: Ag, Cu), trivalent (B: Bi, Sb) and neutral vacant sites with different occupancies. We studied several members of this family such as Ag3BiI6, Ag2BiI5, AgBiI4, AgBi2I7, CuBiI4, Cu2BiI5, though, we will show that many other stoichiometries and cation substitutions are possible. These materials feature direct bandgaps in the range of 1.79-1.83 eV that corresponds to the efficiency limit of ~18% by assuming open circuit voltage of 1.2V, typical optical losses and fill factor for optimized solar cells. The wider bandgap of rudorffites is advantageous tandems with for Si or CIGS with projected detailed balance limit of 45%. As a proof of concept, we demonstrate FTO/c-TiO2/m-TiO2/Ag3BiI6/PTAA/Au solar cell fabricated at ambient conditions with 4.3% efficiency for the best cell.

15.15 - 15.30 C3.O2 Galagan, Yulia
Holst Centre - Solliance

Towards Upscaling and Roll-to-Roll Processing of Perovskite Solar Cells

Yulia Galagan*a, Francesco Di Giacomoa, Santhosh Shanmugama, Henri Fledderusa, Herbert Lifkaa, Fieke van den Bruelea, Gerwin Kirchnera, Harrie Gortera, Ike de Vriesa, Pim Groena, Ronn Andriessena

Holst Centre - Solliance, High Tech Campus 21, Eindhoven, 5656, NL

Perovskite solar cells (PSCs) emerge as very appealing alternative energy sources for the future energy market. With the remarkable lab-scale advances having been achieved to date, investigations towards a high-throughput large-scale production of perovskite devices are now placed on the agenda. The first step toward Roll-to-Roll (R2R) processing is a substitution of spin-coating by slot die coating process that at first glance seems to be a straightforward step. However, crystallization kinetics of perovskite is completely different for these two deposition methods. Moreover, solvents used for the lab-scale manufacturing are not always compatible with R2R manufacturing. Furthermore, typical post treatment tricks, used for fast nucleation and controlled crystallization of the perovskite require adaptation for fast R2R process. We will present our progress on this topic, which includes solvent selection and control of the crystallization kinetics of perovskite layer deposited from “green” solvents.

The intermediate step between spin coating and R2R deposition is so called Sheet-to-Sheet (S2S) process, where the functional layers are deposited on 6”glass and foil substrates. The latest developments allowed us to produce the slot die coated devices with the efficiencies identical to spin-coated ones. The work on large area modules enable manufacturing 6” modules (active area of 168 cm2) with 10% PCE using slot die coating process and laser interconnection technologies. The transfer of the developed S2S process to R2R manufacturing is ongoing. The first experiments show very promising results with the full conversion and fast crystallisation of the perovskite phase deposited from “green” solvents. The morphology and the crystal size are controlled by the optimized deposition and drying conditions.   

Furthermore, in order to reach R2R deposition of all functional layers in the device stack, a novel non-vacuum thin film deposition technology - spatial Atomic Layer Deposition (sALD) is investigated. The first experiments on the replacement of e-beam deposited TiO2 by the sALD deposited layer demonstrate promising results. In parallel, R2R solution processing of SnO2 layer is developed. The quality of R2R deposited layers and their combinations are evaluated by measuring devices performance. We will demonstrate our latest achievements on the technology development for up-scalable manufacturing of perovskite solar cells. Our results are the first solid steps towards up-scaling and future commercialization of PSC technology.

15.30 - 15.45 C3.O3 Mora-Seró, Iván
Universitat Jaume I

Negative Capacitance and Inductive Loop, Again Something Else Is Happening in Perovskite Solar Cells

Iván Mora-Seró*

Universitat Jaume I, Av. de Vicent Sos Baynat, s/n, Castell, 12071, ES

Perovskite solar cells are surprising the photovoltaic community as unconventional behaviors have been reported. In most of the cases the origin of these behaviors is not completely understood and also, very important for the final application, how them influence the final performance of the device. Hysteresis, preconditioning effect or large low frequency capacitances have received high attention but other phenomena as inductive loops and/or negative capacitance have been studied significantly less, in part, as their implications in the final performance of the device were not clearly established. An overview of different systems in which these effects are observed is presented. We unambiguously demonstrate a direct correlation between the observation of the negative capacitance and a corresponding decrease on performance of the device, manifested by a reduction of open circuit potential and fill factor. On the other hand we discuss the influence of injection processes, more concretely between TiO2 electron selective contact and perovskite, in the observation of this phenomena. This presentation stress the necessity of establishing the physical origin of negative capacitance in perovskite solar cells due to the important implications in the final performance.

15.45 - 16.00 C3.O4 Pulvirenti, Federico
School of Chemistry and Biochemistry, Georgia Institute of Technology

Approaches for pinhole-free electron transporting layers

Federico Pulvirenti*a, David McMeekinb, Berthold Wegnerc, Nakita Noelb, Raghunath Dasaria, Norbert Kochc, Henry Snaithb, Seth Marderb

a, School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30333-0400, US
b, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK
c, Humboldt-Universitat zu Berlin, Institut fur Physik and IRIS Adlershof, AG Supramolekulare Systeme, Brook-Taylor Strasse 6, 12489 Berlin, DE

Two approaches to reduce non-radiative recombination in perovskite solar cells (PSCs) will be presented. Both approaches aim at preventing or limiting the dissolution of fullerene-based electron-transporting layers (ETLs) by solvents like DMF, from which the perovskite layer is usually cast.

First, we synthesized a crosslinkable fullerene derivative, PCBCB, which is solution processable but is not dissolved by DMF. A smooth, thin and continuous ETL can be obtained while retaining the excellent electronic properties of fullerenes. n-doping of PCBCB was explored to assess whether the conductivity of the ETL could be increased, and more efficient PSCs could be obtained. Commonly used n-dopants are unstable in air, form byproducts and tend to diffuse in the device. We synthesized a moderately air-stable n-dopant, which transfer electrons to ETLs without forming byproducts and is sufficiently large not to diffuse in the device. PCBCB can be n-doped and an increase in stabilized power output up to 1.5% is observed upon n-doping.

The second approach consist in using poorly soluble perylene derivatives as materials for ETLs. The electron-collection barrier between the ETL and the electrode was tune via vacuum-deposition of a dopant to increase fill factor and open-circuit voltage of solar cells. Extensive characterization studies to monitorn changes in work-function of the electrode, and charge extraction from the ETL were performed. 

We therefore show two different strategies, one compatible with solution processing and one with vacuum-deposition techniques, to tune the morphology of the ETL and the interfacial energy barrier at the n-contact.

16.00 - 16.30 Coffee break
Chair: Udo Bach
16.30 - 16.45 C3.O5 Domanski, Konrad
Ecole polytechnique federale de Lausanne

The quest for stability of perovskite solar cells

Konrad Domanski*a, Anders Hagfeldtb, Michael Grätzela

a, Ecole polytechnique federale de Lausanne, EPFL SB ISIC LPI CH G1 526, Lausanne, 1015, CH
b, Ecole polytechnique federale de Lausanne, EPFL SB ISIC LSPM CH G1 526, Lausanne, 1015, CH

While the power conversion efficiencies of perovskite solar cells (PSCs) have rapidly achieved remarkable values of 22.1%, this has not been matched by equal developments in long-term stability. At this stage, operational stability is considered one of the main obstacles for the commercialization of PSCs and as such, the attention of the research community has been steadily shifting towards making PSCs not just efficient but foremostly – stable.

This presentation will summarize the combined efforts of LPI-LSPM, two groups at EPFL, towards improving the stability of PSCs and understanding the degradation processes within them. First, the parameter space for ageing PSCs will be outlined and the infrastructure we have recently built specifically for that purpose will be presented.

The presentation will then address the importance of perovskite composition[1,2] and device architecture[3] on stability and performance of PSCs. The Au migration problem will be discussed in detail along with its all-important consequences for stability testing protocols.[4] Alongside, several ways around it will be presented: diffusion barriers, high-temperature stable hole transporting materials[1,5] and both carbon cloth[6] and carbon nanotube[7] back contacts. The good stability of carbon-based contacts is an especially welcomed news for the efforts to commercialize the PSC technology.

The final part of the presentation will summarize what we have learned about the degradation process itself. Firstly, the partially reversible nature of PSC ageing will be explained as the result of mobile cations on the timescale of hours.[8] Light will be shone also, on how different ageing conditions influence ageing behaviour - specifically temperature, light spectrum and electronic load on the device. On this basis, an ageing protocol will be proposed in an effort to bring the community to a consensus on how to age PSCs with all their peculiarities.

The presentation is an attempt to summarize the results published in 8 scientific papers over the last year, as well as our ongoing work. We would like to look at this body of work as a whole to draw general conclusions on why PSCs age, how this can be assessed objectively and how it could be prevented. 

[1] Saliba, M. et al. Science 354, 206–209 (2016).

[2] Saliba, M. et al. Energy Environ. Sci. 9, 1989-1997 (2016).

[3] Anaraki, E. H. et al. Energy Environ. Sci. 9, 3128–3134 (2016).

[4] Domanski, K. et al. ACS Nano 10, 6306–6314 (2016).

[5] Matsui, T. et al. ChemSusChem 9, 2715 (2016).

[6] Gholipour, S. et al. Adv. Energy Mater. 6, (2016).

[7] Aitola, K. et al. Adv. Mater. Accepted, (2017).

[8] Domanski, K. et al. Energy Environ. Sci. (2017).

16.45 - 17.00 C3.O6 ,

b, .Department of Physics University of Gothenburg , G�teborg 41296, SE
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, JP
a, Helmholtz Zentrum Berlin, Hahn-Meitner-Platz 1, Berlin, 14109, DE
b, Albert-Ludwigs-Universit�t Freiburg, Fahnenbergplatz 79085 Freiburg, DE
a, Shri V. S. Naik Arts, Commerce And Science College, Raver (M.S.), India, Burhanpur Road, Raver, 425508, IN
a, VU University Amsterdam, De Boelelaan 1081, Amsterdam, 1081, NL
a, Zurich University of Applied Sciences, Wildbachstr. 21, Winterthur, 8401, CH
b, Laboratory of Photonics and Interfaces, EPF Lausanne, Lausanne, 1015, CH
a, LEPABE � Faculdade de Engenharia, Universidade do Porto, Rua Dr Roberto Frias, 4200-465 Porto, Portugal
b, IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de F�ısica e Astronomia, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal
c, Institut des Sciences et Ing�enierie Chimiques, Ecole Polytechnique F�ed�erale de Lausanne (EPFL), 1015 Lausanne, Switzerland
d, Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, 29208, USA
a, SEFIN, Avda. Sos Baynat 3 bajo 6, Castell�n, 12006, ES
a, IPCMS, University of Strasbourg - CNRS, 23, rue du Loess, Strasbourg Cedex, 67034, FR
b, Institute f. Theoretical and Physical Chemistry, Chemistry Dept., W.-Goethe-University Frankfurt , 60438 Frankfurt, GE
a, Bar Ilan University, Ramat-Gan, Ramat-Gan, 52900, IL
b, Nanyang Technological University, 50 Nanyang Drive, Singapore
b, UMDO, Instituto de Ciencia de los Materiales, Universidad de Valencia, Valencia, 46071, ES
c, Center for Nano Science and Technology of Italian, via Pascoli 70/3, Milano, 20133, IT

17.00 - 17.15 C3.O7 Tournebize, Aurélien
University of Bordeaux, CNRS, Bordeaux INP, IMS, UMR 5218

Interfacial degradation in organic solar cells

Aurélien Tournebize*a, Giorgio Mattanab, Thérèse Gorissea, Guillaume Wantza, Lionel Hirsha, Sylvain Chambon*a

a, University of Bordeaux, CNRS, Bordeaux INP, IMS, UMR 5218, F-33405 Talence, FR
b, Univ. Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086 CNRS, 15 rue J-A de Baïf, 75205 Paris Cedex 13, FR

The understandings of interfacial phenomena are of paramount importance in organic electronics. During their operating time, organic solar cells (OSCs) are submitted to many stresses such as light, oxygen, temperature and humidity which can influence the interface properties and ultimately the device performances. Depending of the stresses and materials concerned, different mechanisms of degradation can occur at the interfaces: photochemical reactions, diffusion, delamination, energy level changes etc…

Herein, we have investigated the role of various electron transporting layers (ETLs) on the degradation mechanism of OSCs, for different donor/acceptor active layers (ALs). In particular, the influence of the UV component of the incoming light on the initial degradation step of OSCs (so-called burn-in) is assessed. Using a combination of characterization tools (impedance spectroscopy and X-ray photoemission spectroscopy) we managed to correlate the changes in the electric characteristic of the devices to modification at the AL/ETL interface. A specific degradation mechanism was identified for TiOx which result in a loss of the built-in potential in the devices. The obtained results enable us to provide strategies to improve the stability of the Al/ETL interface in OSCs. In this context, we investigated the influence of self assembled monolayers (SAMs) to reduce the degradation at the AL/ETL interface.

17.15 - 17.30 C3.O8 Ning, Zhijun
ShanghaiTech University

High Efficiency Colloidal Quantum Dot Solar Cells with Inverted Structure

Zhijun Ning*a, Ruili Wanga, Yuqin Liaoa

ShanghaiTech University, 100 Haike Road , Shanghai, 201210, CN

High efficiency colloidal quantum dot solar cells with inverted structure

Ruili Wang, Yuqin Liao, Zhijun Ning*

2 School of Physical Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai 201210, China


Colloid quantum dots (CQDs) solar cells received great attention in recent years due to its solution processability and strong light harvesting capability in infrared region. The efficiency of CQD solar cells has been improving quickly in recent years, with certified power conversion efficiency up to 11.3%. The use of quantum dots surface engineering effectively reduced defects and improve carriers transport. In addition, device structure engineering significantly prompted the carriers transporting and inhibited interfacial recombination.1 Unlike most other solar cells, both normal structure and inverted structure exhibit similar high efficiency, the efficiency of CQD solar cells with inverted structure is generally poor (below 5%). In this work, we fabricated lead sulfide CQD solar cells with inverted structure by using nickel oxide as bottom hole transporting layer. The best device show short circuit current density of 27.6 mA/cm2, open circuit voltage of 0.53 V, fill factor of 65.7% and an overall power conversion efficiency (PCE) of 9.70% under standard 1.5G solar illumination2. This indicate that inverted structure, with appropriate material and interface design, could be another opportunity for more efficient CQD-based photovoltaics.


1. Ruili Wang, Yuequn Shang, Pongsakorn Kanjanaboos, Wenjia Zhou, Zhijun Ning*, and Edward H. Sargent*, Energy Environ. Sci., 2016,9, 1130-1143.

2. Ruili Wang, Yuqin Liao, Zhijun Ning*, manuscript in preparation

Session D3
Chair: Gerrit Boschloo
14.30 - 15.00 D3.IS1 Berlinguette, C. P.
Departments of Chemistry and Chemical Engineering, University of British Columbia

Using Infinitesimally Weak Intermolecular Interactions to Boost DSSC Photovoltages

C. P. Berlinguette*

Departments of Chemistry and Chemical Engineering, University of British Columbia, 2036 Main Mall, Vancouver, 0, CA

High power conversion efficiencies (PCEs) in the dye-sensitized solar cell (DSSC) are contingent on the rate of dye regeneration by the electrolyte species being faster than competing interfacial reactions.  Our program is therefore interested in affecting different dye-electrolyte interactions as a means of boosting cell photovoltages.  We have successfully demonstrated an enhancement in photovoltage where, for example, intermolecular halogen bonding interactions exist between a nucleophilic electrolyte species and a photo-oxidized dye immobilized on a titanium oxide surface.  A series of optical, transient absorption, and X-ray absorption spectroscopic measurements on a homologous series of dyes have collectively been used to resolve that the photovoltage is responsive to halogen bonding interactions that exist only between the oxidized dye and the electrolyte.  These results are surprising in that it shows that a distinct minority of dyes on the surface have a profound effect on DSSSC performance.  These results, as well as other data pertinent to other intermolecular interactions, will be presented to highlight how strikingly weak interfacial interactions can have a profound effect on the performance of the DSSC. 

15.00 - 15.15 D3.O1 Abdi-Jalebi, Mojtaba
Optoelectronics Group, University of Cambridge

Lead halide back contact perovskite solar cells

Mojtaba Abdi-Jalebi*a, Luis M. Pazos-Outóna, Mejd Alsaria, Richard H. Frienda

Optoelectronics Group, University of Cambridge, Cavendish Laboratory, J J Thomson Avenue, Cambridge, CB3 0HE, GB

Interdigitated back contact (IBC) solar cells are currently the performance leading technology in silicon-based photovoltaics. Recently, lead-halide perovskites have emerged as high-performance photovoltaic materials and are a promising candidate for commercial thin film photovoltaic applications. Here, we demonstrate an IBC solar cell based on mixed cation lead iodide perovskite. The devices are fabricated by electrodeposition of electron (TiO2) and hole (PEDOT) selective contacts on patterned ITO electrodes. We find that the overall efficiency of our devices is limited by photocurrent extraction. Spatially-resolved photoluminescence (PL) and photocurrent (PC) measurements reveal an energy barrier at the interface with PEDOT. We find that after reverse biasing the device, the energy barrier is overcome, improving photocurrent generation in the device. We show a method to electrically measure the diffusion coefficient in perovskite films, combining the IBC architecture and optical microscopy. The combination of these results illustrates the potential of combining an IBC architecture and optical microscopy, to understand the fundamental processes limiting the performance of perovskite back-contacted solar cells. In addition, the lateral geometry achieved in the IBC architecture forms a powerful and versatile tool to study charge transport and collection on arbitrary interfaces with the perovskite thin films by means of simple optical techniques such as spatially resolved photocurrent and photoluminescence.

15.15 - 15.30 D3.O2 Najafi, Mehrdad
ECN – Solliance

Highly efficient(16.1% stabilized) and stable(T80>1000h, 1 sun, 35°C) flexible inverted perovskite solar cells with fully inorganic charge extraction layers

Mehrdad Najafi*a, Francesco Di Giacomob, Santhosh Shanmugamb, Dong Zhanga, Afshin Hadipourc, Wiljan Verheesa, Alessia Senesb, Yulia Galaganb, Tom Aernoutsc, Sjoerd Veenstraa, Ronn Andriessenb

a, ECN – Solliance, High Tech Campus 21, 5656 AE, Eindhoven, Netherlands
b, Holst Centre/TNO – Solliance, High Tech Campus 21, 5656 AE, Eindhoven, Netherlands
c, Imec – Solliance, Thin Film PV, Leuven, B-3001, Belgium

Here we report the fabrication of highly efficient and durable flexible inverted triple cation perovskite solar cells through a simple and low-temperature solution process. Pre-synthesized, solution-derived NiOX and ZnO nanoparticles films were employed as a hole transport layer (HTL) and electron transport layer (ETL) respectively, for a flexible organic−inorganic hybrid perovskite solar cell. The metal oxides ETL and HTL solutions are deposited at room temperature without any further annealing or treatment. We produce the triple cation perovskite(Cs0.05(MA0.17FA0.83)0.95Pb(I0.27Br0.3)) films in a single step from a solution containing a mixture of PbI2, PbBr2, FAI, MABr and CsI. As a reference for triple cation perovskite, ultra-smooth and pinhole-free absorbing layers are also fabricated using MAPbI3 perovskite. For MAPbI3 perovskite, champion PCE of 17.7% with a high fill factor of 0.84 was achieved with a stabilized output efficiency of 16.6% on rigid Glass/ITO substrates (comparing with 15.3% PCE with 14.9% stabilized output efficiency for the flexible PEN/thin film barrier/ITO substrates). However using the triple cation perovskite, with the same extraction layers yields a high stabilized power conversion efficiency of 17.7% on rigid Glass/ITO substrates Optimized devices for both of MAPbI3 and triple cation perovskite layers, exhibited negligible current density–voltage (J–V) hysteresis. More interestingly, we proved for the first time the durability of flexible PSC under simulation of operative condition (1 sun, maximum power point tracking,  35°C, N2, without encapsulation): . over 85% of the maximum stabilized output efficiency was retained after 1000h ageing employing a thin MAPbI3 perovskite (over 90% after 500h with a thick triple cation perovskite )This represent a results comparable to similar state of the art rigid PSC, and represents a breakthrough in the stability of flexible PSC using ETL and HTM layers compatible with roll to roll production speed thanks to their room temperature processing. 

15.30 - 15.45 D3.O3 Sahli, Florent

Perovskite/silicon tandem solar cells: challenges towards high-efficiency in 4-terminal and monolithic devices

Florent Sahli*a, Jérémie Wernera, Matthias Bräuningera, Bertrand Paviet-Salomonb, Loris Barraudb, Raphäel Monnarda, Brett Kaminob, Davide Sacchettob, Arnaud Walterb, Soo-jin Moonb, Jonas Geissbuehlerb, Christophe Allébéb, Matthieu Despeisseb, Sylvain Nicolayb, Björn Niesena, b, Christophe Ballifa, b

a, PVlab, EPFL, Rue de la maladière 71B, Neuchâtel, 2000, Switzerland
b, PV-center, Jaquet-Droz 1, 2002 Neuchâtel, Switzerland

Crystalline silicon solar cells are approaching their theoretical efficiency limit of 29.4%, with the record value currently at 26.6%. One of the most promising approaches to overcome this efficiency limit relies on reducing thermalization losses by stacking several absorber materials with different bandgaps in a multi-junction device. With a tunable band gap, low material cost, compatibility with various fabrication techniques and a high performance of up to 22.1%, perovskite solar cells represent a very promising top cell candidate for tandem solar cells with >30% efficiency potential when combined with a silicon bottom cell. A perovskite/silicon tandem solar cell can be fabricated with mainly two approaches: as a mechanically-stacked 4-terminal tandem or a monolithically-integrated 2-terminal tandem, where the top cell is directly processed onto the bottom cell. Both configurations have the potential to exceed 30% efficiency and have their own advantages, but also present several challenges, either in complex system integration for the 4-terminal configuration or, in the case of a monolithic configuration, the challenging manufacturing of the sub cells due to the required process compatibility.Here, we present the development of infrared-transparent perovskite solar cells with high efficiencies of 15.2% and 1 cm2 active area, allowing the fabrication of fully integrated mechanically stacked 4-terminal tandem devices where both subcells have the same area. Such a tandem had a total efficiency of 23.2%, as compared to 25.6% when using a small (i. e., 0.25cm2) area perovskite top cell with 16.2% efficiency. We present recent progress we made on the improvement of perovskite composition, as well as electron and hole transporting layers to achieve higher uniformity and conformity with lower pinhole density.  We then show how this development on 4-terminal tandems can help the development of monolithic 2-terminal tandem cells, illustrated with 1 cm2 devices having efficiencies >21%. Finally, we discuss the role of parasitic absorption in the transport layers and provide strategies to reduce these losses and further improve monolithic tandem performance. In summary, we demonstrate record efficiency mechanically stacked 4-terminal tandem cells with up to 25.6% efficiency for small cells and up to 23.2% on a 1 cm2 fully integrated device. This was realized through the development of large infrared-transparent perovskite cells with up to 15.2% efficiency on 1 cm2 aperture area. Finally, we present strategies to reduce parasitic absorption, which particularly limits the performance of monolithic tandem devices. 

15.45 - 16.00 D3.O4 Dutta , Viresh
Indian Institute of Technology Delhi, New Delhi

Synthesis of Nanocomposites containing MoO3 and Au nanoparticles via Continuous Spray Pyrolysis (CoSP) technique for plasmonic enhanced Photovoltaic devices

Charu Dwivedi a, Viresh Dutta *a

Indian Institute of Technology Delhi, New Delhi, Photovoltaic Lab , Center for Energy Studies, IIT Delhi, New Delhi, 110016, IN

Over the past few years, the efficiencies of OPVs have been improved substantially to over 10% which needs to be further improved to compete with inorganic photovoltaic devices [1]. Additionally, inferior operating stability is also a problem requiring emphatic concern. The thickness of the photoactive layer is limited largely to ∼100 nm for effective charge collection and reduced charge-recombination loss. To increase the absorption efficiency using thin films, many light-trapping approaches have been proposed. One simple approach could be the introduction of metal nanoparticles for triggering localized surface plasmon resonance (LSPRs) [2-4]. For this purpose, Au nanoparticles have been introduced into the anode i.e. MoO3 layer since poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) suffers from the problem of long-term stability because of its acidic and hygroscopic nature.Continuous Spray Pyrolysis (CoSP) technique was used for the synthesis of nanocomposites containing MoO3 nps and Au nps. For this purpose, ammonium heptamolybdate (0.05M) in DI water was used as the precursor solution and chloroauric acid was added to it in different weight ratios. It was found that the nanoparticles thus collected were a mixture of MoO3 and Au nps having size 100nm and 10nm respectively. This nanocomposite can be further used as a precursor for solution processed anode layer in organic photovoltaic devices or other PV devices.As has been reported, the AuNP/MoO3 nanocomposite layer is one of the most promising candidates for increasing the light-harvesting ability without significantly sacrificing the charge transport and/or collection efficiencies in OPVs. More importantly, the devices made of the MoO3 buffer layer containing Au NPs exhibited superior stability.The effect of MoO3 layer in OPV with PTB7 as the photoactive layer has already been studied [5]. Now this work will be extended to seeing the effect of Au and MoO3 nanocomposite layer in OPVs with PTB7 as the photoactive layer and Al contact. References[1] Li, G.; Zhu, R.; Yang, Y. Nat. Photonics 2012, 6, 153−161.[2] Wang, D. H.; Park, K. H.; Seo, J. H.; Seifter, J.; Jeon, J. H.; Kim, J. K.; Park, J. H.; Park, O. O.; Heeger, A. J. Adv. Energy Mater. 2011, 1, 766−770.[3] Li, X.; Choy, W. C. H.; Lu, H.; Sha, W. E. I.; Ho, A. H. P. Adv. Funct. Mater. 2013, 21, 2728−2735.[4] Chen, F. C.; Wu, J.-L.; Lee, C. L.; Hong, Y.; Kuo, C. H.; Huang, M. H. Appl. Phys. Lett. 2009, 95, 013305-1−013305-3.[5] Dwivedi C.; Dutta V. PVSEC 26, oral presentation 

16.00 - 16.30 Coffee break
Chair: Gerrit Boschloo
16.30 - 16.45 D3.O5 Feihl, Sebastian
ZAHNER-elektrik GmbH & Co.KG

Complementing Intensity Modulated Photo Spectroscopy Applied on Organic Solar Cells with Fast Intensity Transient Measurements

Sebastian Feihl*a, Nicola Gasparinib, Gebhard Mattb, Thomas Kunzc, Michael Multerera, Christoph Brabecb, Carl-Albrecht Schillera

a, ZAHNER-elektrik GmbH & Co.KG, Thueringer Strasse 12, Kronach, 96317, DE
b, 2) i-MEET, University Erlangen-Nuremberg, , Martensstrasse 7, Erlangen, 91058, DE
c, ZAE Bayern, Immerwahrstrasse 2a, Erlangen, 91058, DE

Perovskite Solar Cells (PSCs) have emerged as a very promising alternative in comparison to silicon based solar cells due to the combination of high light absorption coefficients and outstanding solar energy conversion efficiencies of more than 20% with simple and cheap methods of fabrication like spin coating or other fluid-to-solid transformation processes [1,2].

The dynamic response of photo voltage (IMVS) a nd photocurrent (IMCS) on light, modulated with changing frequencies, is generally addressed as Intensity Modulated Photo Spectroscopy (IMPS) [3,4,5]. It is a linear, small signal method close to Electrochemical Impedance Spectroscopy (EIS). IMPS is a technique popular for instance in the fields of Dye Sensitized Solar Cells (DSSC) when evaluating the competition between photo charge carrier lifetime and diffusion speed. IMPS intentionally uses bias light superimposed with a small modulation in order to maintain linearity [3,4,5]. On the contrary, intensity transients leave linearity. This is due to the large perturbation induced by switching light from the on-state to the off-state, or vice versa.  A couple of characteristic properties are assumed to be in steady state in the case of IMPS, but they are changing dramatically under light transients. The latter technique is offering the possibility of getting additional insights into ultrafast processes. It is therefore advantageous, when linear dynamic measurements under frequency variation, like IMPS and IMVS, can be put in relation to measurements of transient behaviour in the time domain.In the present work IMPS data of an Organic Solar Cell (OSC) sample were recorded at specific bias intensities. The spectra were interpreted by means of AC modelling and fitting. For comparison, the same samples were characterized by means of fast intensity transients, again. Therefore, the intensity was switched off within 80 ns, with and without keeping the background intensity at a certain bias. The results were compared with the IMPS results and the contribution of the photoconductivity could be identified.

1   N.-G. Park, J. Phys. Chem. Lett., 2013, 4, 2423–2429.

2   G. Niu, X. Guo and L. Wang, J. Mater. Chem. A, 2015, 3, 8970–8980.

3   E. A. Ponomarev and L. M. Peter, J. Electroanal. Chem., 1995, 396, 219–226.

4   Y. Zhao, A. M. Nardes and K. Zhu, Faraday Discuss., 2014, 176, 301–312.

5   G. O. Kim and K. S. Ryu, Bull. Korean Chem. Soc., 2012, 33, 469–472.

16.45 - 17.00 D3.O6 Ruhman, Sanford
Hebrew University of Jerusalem

Watching exciton dissociation and subsequent phonon activation in Lead Halide Perovskites with <10 fs laser spectroscopy

Tufan Ghosha, Sigalit Aharona, Lioz Etgara, Sanford Ruhman*a

Hebrew University of Jerusalem, Institute of Chemistry, Hebrew University, Jerusalem, 91904, IL

Spectral evolution following above band edge excitation of MAPbBr3 and MAPbI3 thin films has been followed with sub 10 fs pump - multichannel probe spectroscopy. Results demonstrate a delayed rise in the below band edge induced absoption which measure the timescale for breackup of hot excitons in the iodide perovskite. In the bromide and iodide transient absorption surrounding the exciton peak is modulated by optic phonons. An analysis of these modulations shows that they are due primarily to spectral shifting of the exciton peak, and that both phonons related to the inorganic framework and to the organic cations couple to this transition. from the amplitude of these modulations the exciton phonon copupling energies are estimated and are found to be in reasonable agreement with previous values extracted from emission lineshape analysis. In the lecture we will connect these findings with recent studies using 2D electronic spectroscopy, and with suggestions that the coupling causes a dressing of electronic excitations with polar phonons in the form of large polarons.

17.00 - 17.15 D3.O7 Johansson, Erik M. J.
Uppsala University

Environmental friendly perovskite and quantum dot solar cells

Erik M. J. Johansson*

Uppsala University, Dep. Chemistry - Angstrom, Uppsala, 75120, SE

Perovskite- and quantum dot solar cells have shown a tremendous development the recent years. The most common perovskite- and quantum dot solar cells are based on lead (Pb), and although a small amount of Pb is used, the toxicity may be a concern for a very large scale application in the future. Therefore it would be advantageous to find alternative materials based on less-toxic metals. We have specifically focused on bismuth based halides, which have rather similar properties compared to the lead based perovskites, and we have shown that bismuth halides work as solar cell materials.1,2,3 Here we will show our most recent results on different bismuth halide solar cells and the combination with different electron and hole transport materials for optimizing the solar cell performance. Interestingly we find that the hole transport material has a large impact on the efficiency of the device, and we investigate the possible reasons for this using different advanced methods. We have the recent years also worked with quantum dot (QD) solar cells, and our most efficient QD solar cells are also based on lead (PbS). Therefore we have also started to investigate alternative materials for QDs, and some new results for lead-free quantum dot solar cells will also be presented. 


(1)    Bismuth based Hybrid Perovskites A3Bi2I9 (A : Methylammonium or Cesium) for Solar Cell Application, B. W. Park, B. Philippe, X. L. Zhang, H. Rensmo, G. Boschloo, E. M. J. Johansson, Advanced Materials, 27, 6806–6813, 2015

(2)    Extended Photo-Conversion Spectrum in Low-Toxic Bismuth Halide Perovskite Solar Cells, M. B. Johansson, H. Zhu, E. M. J. Johansson, J. Phys. Chem. Lett. 7, 3467-3471, 2016

(3)    Bismuth Iodide Perovskite Materials for Solar Cell Applications: Electronic structure, Optical Transitions, and Directional Charge Transport, M. Pazoki, M. B. Johansson, H. Zhu, P. Broqvist, T. Edvinsson, G. Boschloo, E. M. J. Johansson, J. Phys. Chem. C. 120, 29039-29046, 2016

17.15 - 17.30 D3.O8 HSU, Hsien-Yi
School of Energy and Environment, City University of Hong Kong

Optimization of MAPbI3 Perovskite Solar Cells with PbI2 Passivation by Utilizing Scanning Photoelectrochemical Microscopy Imaging

Hsien-Yi HSU*a, Li Jic, Minshu Dub, Ji Zhaob, Edward Yuc, Allen Bardb

a, School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong , 500, CN
b, Center for Electrochemistry, Department of Chemistry, The University of Texas at Austin, Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States, US
c, Microelectronics Research Center, Department of Electrical and Computer Engineering, University of Texas at Austin, Department of Electrical and Computer Engineering, University of Texas at Austin, Austin, Texas 78712, United States, US

A variety of PbI2/MAPbI3 perovskites were prepared and investigated by a rapid screening technique utilizing a scanning photoelectrochemical microscope (SPECM) in order to determine how excess PbI2 affects its photoelectrochemical (PEC) properties. An optimum ratio of 2.5% PbI2/MAPbI3 was found to enhance photocurrent over pristine MAPbI3 on a spot array electrode under irradiation. With bulk films of various PbI2/MAPbI3 composites prepared by a spin-coating technique of mixed precursors and a one-step annealing process, the 2.5% PbI2/MAPbI3 produced an increased photocurrent density compared to pristine MAPbI3 for 2mM benzoquinone (BQ) reduction at − 0.4 V vs Fc/Fc+. As a result of the relatively high quantum yield of MAPbI3, a time-resolved photoluminescence quenching experiment could be applied to determine electron-hole diffusion coefficients and diffusion lengths of PbI2/MAPbI3 composites, respectively. The diffusion coefficients combined with the exciton lifetime of the pristine 2.5% PbI2/MAPbI3 (τPL = 103.3 ns) give the electron and hole exciton diffusion lengths, ~ 300 nm. Thus, the 2.5% PbI2/MAPbI3 led to an approximately 3.0-fold increase in the diffusion length compared to a previous report of ~ 100 nm for the pristine MAPbI3 perovskite. We then demonstrated that the efficiency of liquid-junction solar cells for 2.5% excess PbI2 of p-MAPbI3 was improved from 6.0% to 7.3%.

17.30 - 17.45 Closing
22nd May 2017 - Day 1 (Monday)
4438 Julius Važgėla*, Austėja Galvelytė, Gytis Juška Mismatch of Bimolecular Recombination in Polymer TQ1/Fullerene Blends Employing Different Techniques
4670 Zhen Qiu, Yue Ma, Tomas Edvinsson* Tuning of NiO into an Efficient Electrocatalyst for Water Splitting
4776 Martin Busch*, Thomas Kolbusch, Klaus Crone, Nico Meyer Challenges and solutions in the R2R manufacturing of perovskite solar cells
4780 Raihana Begum, Osman Bakr, Omar Abdelsaboor, Subodh Mhaisalkar*, Nripan Mathews* Tuning Optical Properties in Halide Perovskite Nanocrystals
4783 Katarzyna Pydzinska*, Patryk Florczak, Grzegorz Nowaczyk, Marcin Ziolek Dynamics of charge transfer rates in perovskite solar cells with spiro-OMeTAD and X60 as hole transporting materials.
4792 Sateesh Prathapani*, Divya Choudhary, Sudhanshu Mallick, Parag Bhargava, Aswani Yella Crystallization and Phase evaluation of Formamidinium Lead Iodide hybrid perovskite materials by two step method
4808 Sandy Sanchez*, Ullrich Steiner, Antonio Abate Making high efficiency perovskite solar cells with flash infrared annealing
4813 Dana Medina, Michiel Petrus*, Askhat Jumabekov, Johannes Margraf, Simon Weinberger, Julian Rotter, Timothy Clark, Thomas Bein Directional Charge Carrier Transport in Oriented Benzodithiophene Covalent Organic Framework Thin Films
4814 Arul varman Kesavan, Arun D Rao, Praveen C Ramamurthy* Optical and electronic property tailoring by MoS2-polymer hybrid solar cell
4821 Alessandro Senocrate*, Igor Moudrakovski, Gee Yeong Kim, Tae-Youl Yang, Giuliano Gregori, Michael Graetzel, Joachim Maier The nature of ion conduction in methylammonium lead iodide
4823 Huimin Zhu* The Study of Low Toxicity of Bismuth-based Light Absorbers
4828 Nick Vlachopoulos*, Anders Hagfeldt Developing of a new postgraduate course of electrochemistry for solar energy conversion
4835 Shigeru Kubota*, Yoshiki Harada, Takenari Sudo, Kensaku Kanomata, Bashir Ahmmad, Jun Mizuno, Fumihiko Hirose A novel optical design of organic solar cells integrating high index glass substrate with nanotextured surfaces
4845 Birgit Six, Franz-Peter Wenzl* Linking the influence of PEDOT:PSS solutions to device performance of tin perovskites
4852 Marinakis Nathalie*, Housecroft Catherine, Constable Edwin Characterization and improvement of p-type dye sensitized solar cells
4863 Jenny Baker, Katherine Hooper, Frencesca de Rossi, Simoni Meroni, Daniel Burkitt, Trystan Watson* Processing considerations for commercialization of carbon based mesoscopic perovskite solar cells.
4867 Evelyne Knapp*, Martin Neukom, Stéphane Altazin, Simon Züfle, Beat Ruhstaller Determining the Mobility of Ions in Perovskite Solar Cells – Measurement and Simulation
4870 Joel Troughton, Katherine Hooper, Fransesca De Rossi, Trystan Watson* Humidity Resistant Fabrication of Planar Perovskite Solar Cells and Modules
4875 Andy Thein*, Martin Berry, Jakub Mazurkiewicz, Dongchuan Fu, Jiangjing He Outdoor performance evaluation of glass substrate carbon-based perovskite solar cell modules from Dyesol against commercially available photovoltaic modules during Summer & Autumn in New South Wales, Australia
4878 Tae Woong Kim*, Satoshi Uchida, Ludmila Cojocaru, Tomonori Matsushita, Takashi Kondo, Hiroshi Segawa Crystal phase coexistence in organometal halide perovskite solar cell observed by transmission electron microscopy
4879 Herri Trilaksana*, Gunther Andersson*, Lars Kloo* Investigation of the Effects of Chenodeoxycholic Acid (CDCA) as Co-adsorbent to the N917 Dye in Dye Sensitized Solar Cells using NICISS Techniques and FT-IR Spectroscopy
4882 Timothy Jones*, Benjamin Duck, Kenrick Anderson, Ricky Dunbar, Noel Duffy, Gregory Wilson* Efficient solid-state dye-sensitised solar cell modules
4886 Jaeki Jeong, Jin Young Kim* Ternary halide p-i-n structure perovksite solar cells
4887 Hak-Beom Kim, Hyosung Choi, Cheng-Kang Mai, Jaeki Jeong, Seyeong Song, Guillermo C. Bazan, Alan J. Heeger, Jin Young Kim* Conjugated polyelectrolyte hole transport layer for p-i-n structure perovskite solar cells
4888 Tack Ho Lee, Mohammad Afsar Uddin, Han Young Woo*, Jin Young Kim* Investigation of Charge Carrier Behavior in Highly Efficient Ternary Blend Polymer Solar Cells
4891 Bardo Bruijnaers*, Martijn Wienk, Stefan Meskers, René Janssen The impact of oxygen on charge carrier recombination in planar P-I-N perovskite solar cells
4893 An-Na Cho, Nam-Gyu Park* Novel Hole Transporting Material Based on Acridine Core Unit for High Efficiency Perovskite Solar Cell
4906 Matthias Diethelm*, Lieven Penninck, Stéphane Altazin, Ton Offermans, Rolando Ferrini, Birger Zimmermann, Uli Würfel, Beat Ruhstaller Simulation-Based Investigation of Non-Uniformities for Large Area Organic and Perovskite Solar Cells
4914 Florian Mathies*, Philipp Brenner, Gerardo Hernandez-Sosa, Ulrich W. Paetzold, Uli Lemmer Inkjet printed perovskite layers for optoelectronic devices
4916 Stefano Pisoni*, Fan Fu, Thomas Feurer, Roger Ziltener, Ayodhya Tiwari, Stephan Buecheler All laser-scribed flexible perovskite mini-modules for thin film tandem applications
4917 Fedwa El-Mellouhi*, Akinlolu Akande, Carlo Motta, Sergey Rashkeev, Golibjon Berdiyorov, Mohamed El-Amine Madjet, Asma Marzouk, El-Tayeb Bentria, Stefano Sanvito, Sabre Kais, Fahhad H Alharbi Solar cells materials by design: Hybrid pyroxene corner-sharing VO4 tetrahedral chains
4922 arun dhumal rao, Arul K Varman, Praveen C Ramamurthy* Rare-earth up-conversion nano-composite HTL layer for inverted bulk hetero-junction solar cell
4925 Daniel Ramirez*, Juan Felipe Montoya, John Ciro, Johny Alexander Jaramillo, Santiago Mesa, Mario Alejandro Mejia Escobar, Rafael Betancur, Franklin Jaramillo* P-i-n meso-superstructure perovskite solar cell: towards improved performance, stability and scalability
4934 Núria Montcada, Emilio Palomares*, Ilario Gelmetti Quasi-Fermi Energy Shift for Hole Transport Material in Perovskite Solar Cells.
4935 George Kakavelakis*, Temur Maksudov, Pavlos Tzourmpakis, Michael Papachatzakis, Dimitrios Konios, Constantinos Petridis, Emmanuel Kymakis Graphene-related materials for efficient and stable organic and perovskite solar cells and modules
4939 Mehrad Ahmadpour*, Andre Luis Fernandes Cauduro, Roberto dos Reis, Gong Chen, Andreas Schmid, Horst-Günter Rubahn, Morten Madsen Crystalline MoOx thin-films as hole transport layers in DBP/C70 based organic solar cells
4941 Bernard Wenger*, Pabitra Nayak, Henry Snaith Optical Properties and Charge Trapping in CH3NH3Br3 Perovskites
4944 Christian Weinberger, Muhammad Talha Masood, Jawad Sarfraz, Emil Rosquist, Simon Sandén, Oskar J. Sandberg, Paola Vivo, Syed G. Hashmi, Peter D. Lund, Ronald Österbacka, Jan-Henrik Smått* Impact of film thickness of dip-coated compact TiO2 layers on the performance of mesoscopic perovskite solar cells
4947 Silvia Colodrero*, Guillermo Martinez-Denegri, Paola Mantilla-Perez, Johann Toudert, Jordi Martorell* Semi-transparent perovskite cell for the fabrication of monolithic CIGS-PVK tandem cells without the need of current matching
4948 Severin Habisreutinger* Dopant-Free Planar n-i-p Perovskite Solar Cells with Steady-State Efficiencies Exceeding 18%
4950 Endre Horvath* Formation mechanism of photovoltaic perovskite nanowires
4956 Giorgio Bardizza*, Elena Salis, Ana Maria Gracia Amillo, Thomas Huld, Ewan Dunlop Power matrix measurements of an organic PV mini-module applied to an energy rating analysis
4966 Zahra Andaji Garmaroudi, Mojtaba Abdi-Jalebi*, Sam Stranks, Richard H. Friend Origin of Ion Segregation in Lead Mixed Halide Perovskite 
4972 Tufan Ghosh*, Sigalit Aharon, Lioz Etgar, Sanford Ruhman* Electron-Phonon Coupling in Hybrid Lead Halide Perovskites Studied by Resonant Impulsive Stimulated Raman Scattering
4984 George Kakavelakis*, Konstantina Alexaki, Emmanuel Stratakis, Emmanuel Kymakis Metal nanoparticles doped PEDOT:PSS hole transporter for efficient and stable inverted perovskite solar cells
4985 Byung-wook Park, Hak-Geun Lee, Woon-Seok Yang, Tae-Joo Shin, Nam-Joong Jeon, Sang-Il Seok* Crystallographic Features of Hybrid Lead Halide Perovskite Incorporating Excessive PbI2
4988 Mathias Uller Rothmann, Wei Li, Ye Zhu, Udo Bach, Leone Spiccia, Yi-Bing Cheng*, Joanne Etheridge* Direct Observation of Intrinsic Twin Domains in Tetragonal CH3NH3PbI3
4990 Kyung Taek Cho, Mohammad Khaja Nazeeruddin* Highly efficient perovskite solar cells with a compositionally engineered perovskite/hole transporting material interface
5005 Yu-Ling Guo*, Chao-Kun Hung, Yu-Chun Wu, Xue-Yi Lin, Peter Chen Suitable TiO2 photoanode in dye-sensitized solar cells for sunlight and indoor light harvesting applications
5010 Man Gu Kang*, Myung Lae Lee, Jin Hyuck Heo, Sang Hyuk Im Efficient flexible perovskite photovoltaic devices using TiO2 arrays Ti metal substrate by anodizing
5017 Silver-Hamill Turren-Cruz , Michael Saliba*, Mattew T. Mayer, Hector Juárez Santiesteban, Xavier Mathew, Lea Nienhaus, Moungi G. Bawendi, Michael Grätzel, Antonio Abate, Anders Hagfeldt*, Juan-Pablo Correa-Baena* Next generation of planar perovskite solar cells yield high voltages and efficiency by crystal phase stabilization
5033 Byung-wook Park, Hak-Geun Lee, Woon-Seok Yang, Tae-Joo Shin, Nam-Joong Jeon, Sang-Il Seok* Crystallographic Features of Hybrid Lead Halide Perovskite Incorporating Excessive PbI2
5037 Mohammad Mahdi Tavakoli*, Zhiyong Fan High-quality organohalide lead perovskite films fabricated by layer-by-layer alternating vacuum deposition for high efficiency photovoltaics
5038 Seul-Gi Kim, Dae-Yong Son, Nam-Gyu Park* How to Get Rid of Hysteresis in Perovskite Solar Cells
5039 Kwang-Ho Jung, Nam-Gyu Park* Hysteresis-less, High Efficiency and Stable Perovskite Solar Cells based on Solution Processed SnO2 Electron Transport Layer
5040 Dong-Nyuk Jeong, Do-Kyoung Lee, Nam-Gyu Park* Development of Viscoliquid Coating Solution for Large-area Perovskite Thin Films
5041 Bowen Yang, Ian Weiss, Elena Galoppini, William Willis, Steven Suib, Alexander Agrios* Investigation of Pt-S bonding for dye-anchored platinum nanocatalysts
5044 Alan Dunbar*, Chan Kyu Kwak Improving the production reliability and performance of OPVs by using a conjugated polyelectrolyte additive to improve charge transport through the in the hole transport layer.
5048 Hung-Hsiang Yeh *, Peter Chen * High efficiency 2D/3D perovskite solar cell by Low-Pressure Vapor-Assisted Solution Process.
5049 Jose A. Solera, Andrea Soto*, Leslie W. Pineda* Copper(I/II) complexes based on β-ketoiminato ligand as redox shuttles for DSSCs
5051 Sadig Aghazada, Mohammad Khaja Nazeerudin* Cyclometalated ruthenium complexes for highly efficient dye-sensitized solar cells
5052 Kasparas Rakstys*, Sanghyun Paek, Peng Gao, Paul Gratia, Tomasz Marszalek, Giulia Grancini, Kyung Taek Cho, Kristijonas Genevicius, Vygintas Jankauskas, Wojciech Pisula, Mohammad Khaja Nazeeruddin Molecular Engineering of Face-on Oriented Dopant-free Hole Transporting Material for 19% Perovskite Solar Cells
5053 Jérémie Werner*, Florent Sahli, Matthias Bräuninger, Bertrand Paviet-Salomon, Loris Barraud, Raphaël Monnard, Brett Kamino, Davide Sacchetto, Arnaud Walter, Soo-Jin Moon, Jonas Geissbuehler, Christophe Allebé, Matthieu Despeisse, Sylvain Nicolay, Bjoern Niesen, Christophe Ballif High-efficiency 4-terminal and monolithic perovskite/silicon tandem devices
5054 Tatiana Soto, Andrea Soto-Navarro*, Leslie W. Pineda* Synthesis and evaluation of germanium(II) compounds bearing β-diketiminate ligands as hole conducting materials in perovskite solar cells
5057 Ahmed M. El-Zohry*, Erkki Alarousu, Smritakshi P. Sarmah, Chen Yang , Omar F. Mohammed Photon Re-absorption in Hybrid Perovskite Single Crystals
5058 Merabet Boualem* Could half-metallic ferroelectric SrFeHfO6 double perovskites be useful for solar energy conversion? DFT+U+SO prediction
5059 Javier Urieta, Agustín Molina*, Iwan Zimmermann, Juan Aragó, Enrique Ortí*, Mohammad Nazeeruddin*, Nazario Martín* Designing highly efficient sulfur-rich polycyclic aromatic compounds as hole transporting materials for Perovskite solar cells
5062 Viktor Öberg, Erik Johansson* Ag2S Quantum Dot Solar Cells
5063 Gabriela Gava Sonai*, Ana Flávia Nogueira, Syed Ghufran Hashmi Carbon nanotubes as efficient counter electrodes for dye-sensitized solar cells with copper (I/II) mediator
5064 Ko-Chi Teng, Tzu-Chien Wei* Robust MAxFA1-xPbI3 perovskite single crystal with 1.41 eV band gap
5065 Olivia Ashton*, Henry Snaith A study of the incorporation of mixed cations in perovskite nanocrystals
5066 Konstantins Mantulnikovs*, Andrzej Sienkiewicz*, Péter Matus, Luka Ćirić, Anastasiia Glushkova, Márton Kollár, Endre Horváth, László Forró Morphology and photoluminescence of CH3NH3PbI3 deposits on non-planar, strongly curved substrates
5067 Svetlana Siprova, Alessandra Crispini, Attilio Golemme* Conversion of an evaporated lead halide film to a full-coverage perovskite film
5068 Pavao Andričević*, Márton Kollár, Xavier Mettan, Bálint Náfrádi, Andrzej Sienkiewicz, Dóra Fejes, Klára Hernádi, László Forró, Endre Horváth 3-dimensionally enlarged photoelectrodes by a protogenetic inclusion of vertically aligned carbon nanotubes into CH3NH3PbBr3 single crystals
5069 Pavol Gemeiner*, Michal Hatala, Milan Mikula, Jaroslav Kuliček, Ľubomír Švorc, Matej Mičušík, Mária Omastová, Viera Khunová Improvement of screen-printed PEDOT:PSS counter electrodes of DSSCs by incorporating halloysite nanotubes
5070 Mina Mirsafaei*, Pia Bomholt Jensen, Harish Lakhotiya, John Lundsgaard Hansen, Sanjay K. Ram, Brian Julsgaard, Peter Balling, Horst-Gunter Rubahn, Morten Madsen Sputter Deposited TiOx Thin-Films as Electron Transport Layers in Organic Solar Cells
5071 Zeguo Tang*, Takeru Bessho, Fumiyasu Awai, Takumi Kinoshita, Haibin Wang, Masato M. Maitani, Ryota Jono, Takaya Kubo, Satoshi Uchida, Hiroshi Segawa* Hysteresis-less highly efficient perovskite solar cells via modifying perovskite absorber
5072 Masato Maitani*, Akito Tateyama, Akio Nitta, Wei-Wei Wang, Manabu Sugimoto, Bunsho Ohtani , Yuji Wada , Hiroshi Segawa* Adsorption and Trap-state Control at Perovskite/TiO2 Interface by Exposed Facet of Scaffold for CH3NH3PbI3 (Clx) Perovskite Solar Cells
5073 Nouar Tabet, Fahhad Alharbi* The practical limits of perovskite solar cell efficiency by device simulation
5074 Xiwen Gong, Grant Walters, Randy Sabatini, Frederic Laquai, Edward Sargent* Contact-free and precise measurement of the mobility, diffusion length and trap density of perovskite single crystals
5076 Ibrahim BULUT, Matthieu MANCEAU, Muriel MATHERON*, Solenn BERSON Large area Perovskite-based Solar Modules via Laser-Scribing
5077 Dorothea Scheunemann*, Oliver Kolloge, Sebastian Wilken, Majvor Mack, Matthias Schulz, Arne Lützen, Jürgen Parisi, Manuela Schiek Charge Carrier Recombination Dynamics in Squaraine-Based Bulk-Heterojunction Solar Cells
5078 Natalie Mica, Sondos Almahmoud, Lethy Jagadamma, Graeme Cooke, Ifor Samuel* Development of a planar small molecule donor for organic solar cells
5079 Nina Heikkilä, Senol Öz, Eunhwan Jung, Alexander Möllmann, Arto Hiltunen, Terttu Hukka, Sanjay Mathur, Paola Vivo* Influence of Ambient Working Conditions on the Performance of Planar and Mesoscopic Perovskite Solar Cell Architectures
5080 Kenji Yoshino*, Yohei Yamaga, Himeka Tominaga, Shuzi Hayase Low temperature growth of high quality of FTO films grown by spray pyrolysis
5081 Himeka Tominaga, Kenji Yoshino*, Yuhei Ogomi, Takashi Minemoto, Qing Shen, Taro Toyoda, Shuzi Hayase Control of conduction band offset of ZnMgO buffer layer for perovskite based solar cell
5082 Jongchul Lim, Maximilian T. Hörantner, Nobuya Sakai, Nakita K. Noel, Bernard Wenger, Henry J. Snaith* Effective Mobility Determined by Refractive Index Change of Perovskite at the Sub-Bandgap : Photoinduced Reflection Spectroscopy
5083 Yu-Chieh Liu, Tzu-Chien Wei* Efficient solid-state dye-sensitized solar cells using 3,10-functionalized perylenes sensitizers
5084 Firoz Alam*, Mathilde Bouchard, Jan Hilhorst, Stéphanie Pouget, Maria Méndez, David Djurado, Dmitry Aldakov, Tobias Schulli, Peter Reiss Direct Evidence of Chlorine Induced Preferential Crystalline Orientation in Methylammonium Lead Iodide Perovskites Grown on TiO2
5085 Yu-Hsien Chiang, Hsien-Hsin Chou, Wei-Ting Cheng, Yun-Ju Li, Chen-Yu Yeh*, Peter Chen* Porphyrin-based hole transporting materials for high efficiency and stable perovskite solar cells
5086 Christian Fettkenhauer*, Irina Anusca, Martina Pantaler, Doru C. Lupascu Vapor Deposited Bismuth Iodide and Methylammonium Bismuth Iodide Films for Photovoltaics
5087 Mozhgan Yavari*, Mohammad Mazloum-Ardakani, Somayeh Gholipour, Silver Hamill Turren Cruz, Micheal Saliba, Wolfgang Tress, Micheal Gratzel, Andres Hagfeldt Morphology Control by Carbon Nano particles in Perovskite solar cells for increased heat stability
5088 Manabu Sugimoto*, Anri Tanoue, Larry Xethakis, Hiroshi Segawa Electronic-Structure Informatics on Organic Hole Transport Materials in Perovskite Solar Cells: Lessons from Experiment and Predictions from Computation
5090 Dae Young Park, Hey Ryung Buyn, A Young Lee, Ho Min Choi, Seong Chu Lim*, Mun Seok Jeong* Fast synthesis of bandgap-modulated organic lead halide perovskite single crystals
5091 Stéphane Altazin*, Lidia Stepanova*, Kevin Lapagna, Jérémie Werner, Florent Sahli, Björn Niesen, Christophe Ballif, Beat Ruhstaller* Design of Perovskite/Crystalline-Silicon Tandem Solar Cells
5092 Man-Ning Lu, Tzu-Chien Wei* Electrochemical Impedance Spectroscopy Analysis for Dim Light Dye-sensitized Cells
5093 Claire Greenland, Samuele Lilliu, David Lidzey* Time-Resolved Photoluminescence Mapping for Hybrid Perovskite Thin Films and Solar Cells
5094 Fengxian Xie, Liyuan Han* Molecular Diffusion Engineering via Integrated Nano-carbon Interfacial Contact for Stable Perovskite Solar Cells
5095 Benjamin Feleki*, Francesco Di Giacomo, Guy Bex, Rene A. J. Janssen, Ronn Andriessen, Yulia Galagan Rapid and low temperature processing of mesoporous TiO2 for highly-efficient perovskite solar cells
5096 Ana Milena Cruz Rodriguez*, Pau Bosch, Monica Della Pirriera, Laura Molina, Lorenzo Bautista Solvent engineering for Organo-metal Halide Perovskite Solar Cells
5097 Yasemin Saygili, Marina Freitag*, Anders Hagfeldt, Magnus Soderberg, Norman Pellet, Fabrizio Giordano, Yiming Cao, Ana Belen Munoz Garcia, Shaik Zakeeruddin, Nick Vlachopoulos, Michele Pavone, Gerrit Boschloo, Ladislav Kavan, Jacques Moser, Michael Gratzel Copper Bipyridyl Redox Mediators for Dye-Sensitized Solar Cells with High Photovoltage
5098 Sebastian Svanström*, Ute Cappel, Bertand Philippe, Håkan Rensmo Chemical composition and non-destructive depth profiling of mixed-ion perovskites
5099 srikanth revoju, bertil eliasson*, christain larsen, Ludvig edman* Phenothiazine-Based chromophores for Organic Solar Cells
5100 Jennifer Emara, Klaus Meerholz, Selina Olthof* Exploring the Effect of Heterovalent and Isovalent Cation Incorporation on Hybrid Perovskite Films
5101 Lakshmi S. Subramaniam, Wolfram Kwapil*, Laura E. Mundt*, Bijoy K. Das*, Martin C. Schubert*, Thomas Kroyer*, Simone Mastroianni*, Andreas Hinsch* Optimization of electron-transport layer in perovskite solar cells by characterization using dark lock-in thermography
5102 Lukas Wagner*, Gayathri Mathiazhagan, Julius Gleissner, Sijo Chacko, Simone Mastroianni, Andreas Hinsch In-situ monitoring of opto-electric parameters during methylamine induced crystallization in graphite based mesoscopic perovskite cells
5103 Giacomo Piana*, Chris Bailey* Effect of light soaking and ambient conditions on charge carrier dynamics in CH3¬NH3PbI3 and CH3¬NH3PbI3-xClx thin films.
5105 Subham Dastidar, Aaron Fafarman* Understanding and Improving the Thermodynamic Instability of the Perovskite Phase of CsPbI3
5107 Philippe Holzhey*, Michael Saliba Comparison of the stability of different perovskite compositions at high temperatures
5108 Alberto García-Fernández*, Zahra Moradi, Elena Mas-Marzá, Juan Manuel Bermúdez-García, Socorro Castro-Garcia, Manuel Sanchez-Andujar, María Antonia Señaris-Rodriguez, Francisco Frabegat-Santiago* Role of the moisture molecules on the capacitance and electrical conductivity of (CH3NH3)PbI3 thin-films and powder polycrystalline
5109 Sagar M. Jain, Dibya Phuyal, Tomas Edvinsson, Håkan Rensmo*, Gerrit Boschloo* Lead free Bismuth based perovskite : Improved absorbance and device performance through morphological tailoring
5110 Giorgio Volpi, Nadia Barbero, Valentina Gianotti, Luca Palin, Marco Milanesio*, Claudia Barolo*, Alberto Menozzi, Guido Viscardi New photoactive hybrid nanocomposites and fluorescent polymers for energy downconversion
5111 Anastasiia Glushkova, Marton Kollar, Pavao Andricevic, Endre Horváth, Alla Arakcheeva*, Laszlo Forro Lead Iodide Ethylenediamine: atomic mobility of the organic molecule influences photovoltaic characteristics
5112 Alberto García-Fernández, Juan Manuel Bermúdez-García, Zahra Moradi, Elena Mas-Marzá, Socorro Castro-Garcia*, Manuel Sanchez-Andujar, Francisco Frabegat-Santiago, María Antonia Señaris-Rodriguez Effect of humidity on the electrical properties of bulk MAPbI3 perovskite
5113 Péter Szirmai, Márton Kollár, Endre Horváth, László Forró, Bálint Náfrádi* All-optical THz-wave modulation using ferromagnetic CH3NH3(Mn:Pb)I3 via low-fluence illumination
5114 Xavier Mettan*, Andrea Pisoni, Péter Matus, Jaćim Jaćimović, Bálint Náfrádi, Massimo Spina, Davor Pavuna, László Forró, Endre Horváth* Thermoelectric properties of hybrid halide perovskites
5115 Neha Arora*, M. Ibrahim Dar, Shaik Mohammed Zakeeruddin, Michael Graetzel Extraordinary Stability of Perovskite Solar Cells Yielding Photovoltage as high as 1.53 V
5116 Tania De la Peña, Margarita Sánchez*, Liliana Licea* Preparation of a hydrophobic coating considering optical properties for its application in flexible solar panels
5117 Iwan Zimmermann*, Agustín Molina-Ontoria, Inés Garcia-Benito, Paul Gratia, Nazario Martín, Mohammad Khaja Nazeeruddin High-Efficiency Perovskite Solar Cells using Molecularly-Engineered, Thiophene-Rich, Hole-Transporting Materials
5119 Paul Gratia, Iwan Zimmermann, Jean-Nicolas Audinot, Xavier Jeanbourquin, Giulia Grancini, Edoardo Mosconi, Michael Graetzel, Filippo de Angelis, Kevin Sivula, Tom Wirtz, Md. K. Nazeeruddin* Chemical distribution of elements in efficient mixed perovskite thin films
5120 Huiying Qu*, Miguel A. Arvizu, Claes-Göran Granqvist, Gunnar A. Niklasson Degradation and rejuvenation in electrochromic nickel oxide films
5121 Tania Palmieri*, Edoardo Baldini, Giulia Grancini, Endre Horvath, Ana Alkrap, László Forró, Majed Chergui Ultrafast screening of the internal electric field in CH 3 NH 3 PbBr 3 single crystals
5122 Tiankai Zhang, Mingzhu Long, Jian-Bin Xu*, Keyou Yan Defects Annihilation and Grain Boundary Passivation through Ion Exchange for High Quality Perovskite
5123 Essa A. Alharbi, Shaik M. Zakeeruddin, Michael Graetzel* Role of Guanidinium on the optical, morphological and electrical properties of perovskite solar cells
5125 F. Javier Ramos*, Amelle Rebai, Thomas Guillemot, Nathanaelle Schneider, Nicolas Loones, Jean Rousset Effect of compositional and morphological tuning and its influence on photovoltaic behavior for triple cation (Cs - MA - FA) perovskite solar cells over 20%