Light-induced reversal of ion segregation in mixed-halide perovskites

Wenxin Mao, Christopher R. Hall, Stefano Bernardi, Yi-Bing Cheng, Asaph Widmer-Cooper, Trevor A. Smith, Udo Bach

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114 Citations (Scopus)


Bandgap instability due to light-induced phase segregation in mixed-halide perovskites presents a major challenge for their future commercial use. Here we demonstrate that photoinduced halide-ion segregation can be completely reversed at sufficiently high illumination intensities, enabling control of the optical bandgap of a mixed-halide perovskite single crystal by optimizing the input photogenerated carrier density. We develop a polaron-based two-dimensional lattice model that rationalizes the experimentally observed phenomena by assuming that the driving force for photoinduced halide segregation is dependent on carrier-induced strain gradients that vanish at high carrier densities. Using illumination sources with different excitation intensities, we demonstrate write–read–erase experiments showing that it is possible to store information in the form of latent images over several minutes. The ability to control the local halide-ion composition with light intensity opens opportunities for the use of mixed-halide perovskites in concentrator and tandem solar cells, as well as in high-power light-emissive devices and optical memory applications.

Original languageEnglish
Pages (from-to)55-61
Number of pages9
JournalNature Materials
Publication statusPublished - 2021

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