Understanding Surface Photovoltage Measurements on Metal Halide Perovskite Bilayers
Tomi Baikie a, Philip Calado b, Krzysztof Galkowski a, Zahra Andaji-Garmaroudi a, Akshay Rao a, Sam Stranks a, Jenny Nelson b, Piers Barnes b
a Department of Physics, Cavendish Laboratory, University of Cambridge; Cambridge, UK
b Department of Physics, Imperial College London, London SW7 2AZ, UK
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)
València, Spain, 2022 May 19th - 25th
Organizers: Pablo Docampo, Eva Unger and Elizabeth Gibson
Oral, Tomi Baikie, presentation 092
DOI: https://doi.org/10.29363/nanoge.hopv.2022.092
Publication date: 20th April 2022

Surface photovoltage measurements (SPV) on highly doped semiconductors, such as those used in commercially available photovoltaics and LEDs, can reveal rich information on photoinduced charge dynamics. However, SPV measurements on mixed ionic-electron conductors, such as perovskites, have been poorly understood. We outline a new understanding of SPV measurements, supported by experimental evidence on perovskite bilayers. Our model accurately reproduces these complex SPV measurements, even upon the application of different surface treatments and backing contacts. Importantly, we conclude that the SPV in the perovskite bilayer context can be thought of as a contact-less charge extraction measurement. Our understanding of the SPV measurement in the context of dynamic ionic motion naturally leads to avenues for the selective control of ion migration in perovskite bilayers, demonstrated here by surface passivation treatment. This opens new avenues for the rational design of strategies to improve the photovoltaic properties of perovskite solar cells and LEDs. 

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