Local Structure of 3D Halide Perovskites at High Pressure

Over the past decade, halide perovskites have emerged as promising materials for solar cells, due to their low-cost synthesis and robust semiconducting properties. Challenges remain in terms of improving the chemical stability of these materials, for instance to air, water, and heat, and in terms of reducing their toxicity, as the best performing halide perovskites still incorporate a lead (Pb) cation. Numerous studies have used compression to investigate structure-property relationships in these materials. However, previous structural investigations have only looked at long-range periodicity changes at high pressure. Here, we have performed in situ synchrotron X-ray total scattering at high pressure on a selection of 3D halide perovskites, including the archetypal composition, methylammonium lead iodide (MAPbI₃), to understand the evolution of their short-range, local structure. Preliminary results indicate local disorder due to octahedral tilting which has not been observable through conventional diffraction experiments. Insight into the local structural behavior has the potential to guide future synthetic efforts toward stable, non-toxic perovskite photovoltaics.