ИСТИНА

Besides impressive progress of perovskite solar cells, which deliver now efficiencies of >25.7%, perovskite semiconductors based on complex lead halides opened tremendous opportunities for improving chemical sensors, photodetectors and detectors of ionising radiation, in particular x-rays and gamma rays. The latter applications as well as the featured implementation of perovskite solar cells in space require very high radiation hardness from these materials. Among different types of ionizing radiation, gamma rays have very high penetration ability and hence could hardly be mitigated using simple shielding used to suppress the damage from proton and also electron fluences. Herein, we show that thin films of MAPbI3, FAPbI3, (CsMA)PbI3 and (CsMAFA)PbI3, where MA+ and FA+ are methylammonium and formamidinium cations, tolerate ultra-high doses of gamma rays approaching 10 MGy without significant changes in their absorption spectra. However, only FAPbI3 does not form metallic lead, which features its extreme radiation hardness. Infrared near-field optical microscopy revealed the radiation-induced depletion of organic cations from the grains of MAPbI3 and their accumulation at the grain boundaries, whereas FAPbI3 on the contrary loses FA+ cations from the grain boundaries. Multication (CsMAFA)PbI3 perovskite undergoes a facile phase segregation to domains enriched with MA+ and FA+ cations, which is a principally new radiation-induced degradation pathway. Our findings suggest that the radiation hardness of the rationally designed perovskite semiconductors could go far beyond the impressive threshold of 10 MGy we set herein for FAPbI3 films, which opens many exciting opportunities for practical implementation of these materials. This work was supported by the Russian Science Foundation (project No. 22-13-00463).