Recombination and Localization: Unfolding The Pathways Behind Conductivity Losses in Cs2AgBiBr6 Thin Films

Huygen Jöbsis^a, Valentina Caselli^b, Sven Askes^c, Erik Garnett^c, Tom Savenije^b, Freddy Rabouw^a, Eline Hutter^a

^aInorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University

^bDepartment of Chemical Engineering, Delft University of Technology (TU Delft), The Netherlands, Netherlands

^cCenter for Nanophotonics, AMOLF, Amsterdam, The Netherlands, Science Park 104, Amsterdam, Netherlands

Materials for Sustainable Development Conference (MATSUS)
Proceedings of nanoGe Fall Meeting 2021 (NFM21)

#LightMatter21. Light-Matter Interactions: From Fundamental Spectroscopy to Materials Design

Online, Spain, 2021 October 18th - 22nd

Organizers: Linn Leppert and Marina Filip

Contributed talk, Huygen Jöbsis, presentation 111
DOI: https://doi.org/10.29363/nanoge.nfm.2021.111
Publication date: 23rd September 2021

Lead-halide perovskite thin films have successfully been incorporated as light-absorbing and -emitting layers in a wide range of optoelectronic applications.[1,2] Cs₂AgBiBr₆ (CABB) has been proposed as a promising non-toxic alternative to lead-based perovskites. However, the indirect bandgap and low charge carrier collection efficiencies remain an obstacle for the incorporation of CABB in optoelectronic applications.[3] The limited charge carrier extraction has been ascribed to the high trap density and strong electron-phonon coupling, compared to its lead-containing analogues, resulting in fast charge carrier localization and low charge carrier mobilities. On the other hand, transient absorption experiments show a long-lived charge carrier lifetime ranging over several microseconds.[4] Moreover, at elevated temperatures mobile carriers are observed for microseconds after photoexcitation, highlighting CABB as a potential alternative for lead-halide analogues.[5]

To study the (free) charge-carrier dynamics we have performed transient absorption (TA) spectroscopy and time-resolved microwave conductivity (TRMC) experiments on CABB thin films on nanosecond to microsecond timescales. TA spectroscopy revealed that the charge carrier density decays on a 40-nanosecond timescale but a fraction of the photogenerated holes near the valence band maximum have a lifetime ranging over several microseconds. TRMC measurements showed that these long-lived carriers are, however, not mobile. Comparison of the TRMC and TA traces shows that the conductivity loss is the result of a combined effect of charge carrier loss and localization. Finally, we estimate that the charge carrier diffusion length is ca. 100 nm. This is of the same order of magnitude as the grain size, suggesting that grain boundaries are an important contributor to charge-carrier loss.

References:

[1] Stranks, S. D. & Snaith, H. J. Metal-halide perovskites for photovoltaic and light-emitting devices. Nat. Nanotechnol. 10, 391–402 (2015).

[2] Huang, H., Pradhan, B., Hofkens, J., Roeffaers, M. B. J. & Steele, J. A. Solar-Driven Metal Halide Perovskite Photocatalysis: Design, Stability, and Performance. ACS Energy Lett. 5, 1107–1123 (2020).

[3] Longo, G. et al. Understanding the Performance-Limiting Factors of Cs2AgBiBr6 Double-Perovskite Solar Cells. ACS Energy Lett. 5, 2200–2207 (2020).

[4] Hoye, R. L. Z. et al. Fundamental Carrier Lifetime Exceeding 1 µs in Cs2AgBiBr6 Double Perovskite. Adv. Mater. Interfaces 5, 1800464 (2018).

[5] Bartesaghi, D. et al. Charge Carrier Dynamics in Cs2AgBiBr6 Double Perovskite. J. Phys. Chem. C 122, 4809–4816 (2018).

Acknowledgements:

Huygen Jöbsis and Eline Hutter acknowledge funding from the Dutch Research Council (NWO) under the grant number VI.Veni.192.034. Huygen Jöbsis and Eline Hutter are further supported by the Advanced Research Center Chemical Building Blocks Consortium (ARC CBBC). Valentina Caselli and Tom Savenije acknowledge funding from the Dutch Research Council (NWO), grant number 739.017.004. Sven Askes acknowledges funding from the Dutch Research Council (NWO), grant number VI.Veni.192.062.

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.

MATSUS

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.

International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics

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.