Thermal and chemical durability of metal halide perovskite CsPbBr3 single crystals

Halide perovskite CsPbBr3 single crystals have shown promising applications in high-energy radiation detection because of their high gamma-ray blocking capability, strong hole carrier transport capability, and manufacturing feasibility. However, the soft ionic properties of perovskite octahedral lattice facilitate the phase transformation of CsPbBr3 under a hydrothermal environment, which significantly limits their application. The current work systematically studied the phase stability of the CsPbBr3 single crystals under high temperatures and high humidity to accelerate their potential application in high-energy radiation detection. Thermal and water degradation behaviors of the CsPbBr3 single crystals under elevated temperature were investigated for the first time via in situ Raman spectroscopy and semi-dynamic leaching testing methods. Results indicated that the CsPbBr3 single crystals exhibited good thermal stability below 460 °C without obvious phase degradation and rapidly transformed to CsPb2Br5, followed by PbBr(OH) with the continuous water interaction. The water interaction and phase degradation mechanism of single crystals with the preferential release of Cs, surface reorganization, and formation of PbBr(OH) alteration layer with rod-like structure was revealed. The phase degradation of CsPbBr3 single crystals along surface defects from the growth process was further confirmed, which can be used to guide subsequent work on single-crystal stability regulation.