Models of Disorder in Halide Perovskites

The structural arrangement of metal halide perovskites varies in space and time. Beyond the conventional vibrations of atoms around their average positions, collective motion in the form of octahedral tilting and molecular librations/rotations introduces additional layers of complexity in the dynamic crystal structure. To complicate matters further, dilute point defects, such as charged vacancies and interstitials, exist in a diverse landscape of extended defects including dislocations, polytypes, and grain boundaries. There can also be chemical gradients due to mixing on the A, B or X crystallographic positions, e.g. as found in mixed formamidinium/methylammonium, tin/lead, and iodide/bromide compounds. I will discuss our latest understanding of these phenomena at the atomic scale drawing from our work on data-driven materials modelling [1,2,3] and linked to multi-modal experimental characterisation [4].<br/><br/>1. "Evolutionary exploration of polytypism in lead halide perovskites", Chemical Science 12, 12165 (2021)<br/>2. "Structural dynamics descriptors for metal halide perovskites", arXiv:2304.04714 (2023)<br/>3. "Dynamic local structure in caesium lead iodide: spatial correlation and transient domains", arXiv:2305.11617 (2023)<br/>4. "Stabilized tilted-octahedra halide perovskites inhibit local formation of performance-limiting phases", Science 374, 1598 (2021)