(461h) Phase Segregation and Structural Instabilities in Halide Perovskites

With halide perovskite photovoltaics on the cusp of commercialization, continued investigation of degradation pathways will help to derisk this exciting new energy technology. Most of the highest efficiency and longest lifetime halide perovskite solar cells to date use some sort of complex material composition based off the material formamidinium lead iodide. These materials are designed to achieve high photovoltaic performance while maintaining robust thermal and phase stability. This presentation will focus on the phase instabilities present in many of these materials. This will include in situ measurements of phase segregation in binary and ternary cation halide perovskite compositions. Additionally, measurements focused on CsPbI₃ as a model system provide a deeper insight into the mechanism of phase transformation and suggest methods for further slowing phase transition kinetics. Characterization and complete description of these effects should lead to better predictions of material and device stability and more accurate predictions of real-world lifetime from accelerated testing data.