Joule
ArticleLayer-by-Layer Degradation of Methylammonium Lead Tri-iodide Perovskite Microplates
Context & Scale
The organolead halide perovskites have shown extraordinary potential for low-cost solution-processable photovoltaic devices, with the power conversion efficiency rapidly soaring beyond 20%. However, the perovskite devices today are generally plagued by their poor environmental and thermal instability, and the atomistic mechanism for the thermal degradation remains largely unexplored. Here we report a systematic in situ transmission electron microscopy investigation of perovskite structure transition at 85°C. Along with theoretical calculations, we discover a surface reaction initiated layer-by-layer degradation pathway during the MAPbI3 perovskite thermal degradation. Based on this finding, we developed a strategy using few-layer hBN encapsulation to restrain the surface reaction and thus considerably improve the thermal stability. This work reveals the atomistic pathway of perovskite structure evolution under heating and suggests a potential strategy for creating perovskite devices with improved stability.