Exploring The Relationship between The Local Structure of Lead Halide Perovskites and Their Macroscopic Properties

Characterised by their exceptional optoelectronic characteristics, hybrid halide perovskites have gained prominence as a viable class of materials for energy conversion applications. Their marked impact is especially noticeable in the field of solar cell technology, where they have demonstrated substantial progress in efficiency. Despite these advancements, fully decoding their unique properties continues to pose a scientific enigma. Of particular interest is the local structure of these materials, which often diverges from their average configuration, and is hypothesised to be a significant determinant of their macroscopic properties.<br/><br/>We employed temperature-dependent diffuse X-ray scattering on a series of perovskite single crystals, enabling us to accurately characterise the local structure in real-space across all crystallographic phases of these perovskites. By developing a simple, computationally inexpensive model that accurately mirrors the experimental diffuse scattering, we were able to gain insights into how the local structure can be modulated through the substitution of A and X-site cations.<br/><br/>By employing a variety of optical microscopy techniques on identical compositions, we established a direct correlation with the emergence of ferroelastic properties in these materials.<br/><br/>Our study thereby underscores the critical role of compositional engineering in tailoring the local structure and, by extension, the macroscopic properties of hybrid halide perovskites.