Light-Induced Phase Segregation in Single-Crystalline Mixed-Halide Perovskite Platelets
Udo Bach a, Wenxin Mao a
a ARC Centre of Excellence in Exciton Science, Department of Chemical and Biological Engineering, Monash University, Clayton, VIC, Australia
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
Invited Speaker, Udo Bach, presentation 281
Publication date: 20th April 2022

Lead halide perovskites have recently emerged as a new class of semiconductor materials with exceptional properties. Their bandgaps can be tuned simply by adjusting their composition, in particular their halide ratio. Unfortunately, light-induced phase segregation is readily observed in mixed-halide perovskites, resulting in a material with inhomogeneous composition and optoelectronic properties on the nanoscale. We studied light-induced phase segregation in single-crystalline platelets, revealing that photoinduced phase-segregation occurs even in absence of grain-boundaries. Surprisingly, the cause, which induces phase-segregation to occur, light, can also be employed to reverse phase-segregation and cause halide-remixing. We show this effect in mixed-halide single-crystalline lead halide perovskite platelets and present a polaron-based two-dimensional lattice model to rationalise our findings [1]. The photoinduced complete reversal of halide-ion segregation under sufficiently high photon fluxes opens opportunities for the future usage of these materials in high power applications such as concentrator solar cells and high-power light-emissive devices.

This work was financially supported by the Australian Research Council through the Centre of Excellence in Exciton Science (CE170100026) and additional grants (DP160104575, LE170100235). We acknowledge financial support from the Australian Government through the Australian Renewable Energy Agency and the Australian Centre for Advanced Photovoltaics (ACAP). W.M. acknowledges an ACAP fellowship supported by the Australian Government through the Australian Renewable Energy Agency (ARENA).

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