Proceedings of 6th International Conference on Hybrid and Organic Photovoltaics (HOPV14)
Publication date: 1st March 2014
Here we investigate the lifetime and degradation mechanisms of Organic Photovoltaic (OPV) devices, based on solution processed MoOx hole transport layers (HTLs) deposited in air, using a number of techniques. The effects on device lifetime of thermally annealing the solution processed MoOx are studied, and are compared to other devices that utilise thermally evaporated MoOx or PEDOT:PSS HTLs.
Introduction
MoOx has been studied extensively as a HTL in OPVs due to its lower lying valence band (in the region of -5.30 to -6.86 eV [1]), which makes it more compatible with low energy gap polymers. MoOx and other transition metal oxides used as hole, or electron, transport layers are often deposited via thermal evaporation. Unfortunately, for low cost and large scale production of OPVs, thermal evaporation steps need to be avoided and, therefore, alternative methods of deposition need to be found.
Solution processing of metal oxide films presents a promising alternative, as this process offers the potential for low temperature, low cost manufacturing. Several groups have reported some success with solution processed MoOx HTLs [2-4], though many require high temperature annealing to form the film.
The method used herein uses a facile synthetic process based on work by S. Murase [4]. A precursor of Ammonium Molybdate Tetrahydrate was dissolved in DI water and Acetonitrile - thermal decomposition of which forms water, gaseous ammonia and MoOx in solution. Thin layers (~5nm) of MoOx were produced by spin coating in air, and were left unannealed or were thermally annealed in air. OPV devices based on an PCDTBT/PC70BM active layer were fabricated using these MoOx HTLs, and their efficiency, lifetime and degradation mechanisms were measured by a combination of device characterisation and impedance spectroscopy.
Results
Initial results show that OPV devices made with a solution processed MoOx HTL and a PCDTBT/PC70BM active layer can achieve efficiencies of up to 5.5%. This is comparable to devices with a thermally evaporated MoOx or PEDOT:PSS HTL.
Preliminary lifetime data shows that devices incorporating solution processed MoOx have shorter lifetimes than devices with thermally evaporated MoOx, with devices with thermally annealed solution processed MoOx having improved lifetimes over those with unannealed solution processed MoOx.
Impedance spectroscopy has also been used to explore the mechanisms that result in device degradation and poor device lifetimes.
[1] I. Irfan, A. James Turinske, Z. Bao, and Y. Gao, Appl. Phys. Lett. 101, 093305 (2012). [2] L. Chen, P. Wang, F. Li, S. Yu, and Y. Chen, Sol. Energy Mater. Sol. Cells 102, 66 (2012). [3] C. Girotto, E. Voroshazi, D. Cheyns, P. Heremans, and B.P. Rand, ACS Appl. Mater. Interfaces 3, 3244 (2011). [4] S. Murase and Y. Yang, Adv. Mater. 24, 2459 (2012).
nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.
Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.
International Conference on Hybrid and Organic Photovoltaics
International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.
The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.