Radiation‐induced instability of organic‐inorganic halide perovskite single crystals

Abstract Organic‐inorganic halide perovskites (OIHPs) are promising optoelectronic materials, but their instability in radiation environments restricts their durability and practical applications. Here, electron and synchrotron X‐ray beams are employed with energies in the tens of keV range, individually, to investigate the radiation‐induced instability of two types of OIHP single crystals (FAPbBr 3 and MAPbBr 3 ). Under the electron beam, the FAPbBr 3 sample exhibits 3‐point star‐style cracks spanning a few micrometers on its surface, and the MAPbBr 3 sample shows bricklayer‐style cracks extending over tens of micrometers on its surface. Under the X‐ray beam, a new composition, PbBr 2 , is identified in both single crystals. Such cracking phenomena and composition evolutions are attributed to the volatilization of organic components according to energy dispersive X‐ray spectroscopy and XRD results. Nanoindentation measurements reveal that beam radiation reduces the Young's modulus of FAPbBr 3 (2%) and MAPbBr 3 (16%) and increases the hardness of both crystals over 10%. A volume‐strain‐based mechanism is proposed in which the energy conversion results from the organic cation loss. The difference between volume strain energy and crack formation energy leads to the variation in crack patterns. This study provides insights into the structural and mechanical instability of OIHP single crystals in high‐energy beam radiation environments.