Different facets of hybrid vapour-vapour deposited halide perovskites

Halide perovskites deposited by physical or chemical vapour deposition techniques are significantly less explored than their solution-processed counterparts. In this talk I will cover our contributions to understanding the hybrid vapour-vapour deposition approach, where one first needs to understand the caveats of the first step (i.e., strong vacuum ~10-6 mbar PVD of the inorganic template), before studying the transformation of the inorganic template into a 3D perovskite upon exposure to organohalide vapours (e.g., formamidinium iodide or methylammonium bromide) in a close-space-sublimation setting in weak vacuum conditions ~ 0.1 mbar. By tracking X-ray diffraction and photoluminescence in-situ, we identify four different regimes of the transformation and expose critical, previously overlooked, external factors that determine the optoelectronic quality of the perovskite thin-films. In the final part, I will present a new degradation-inversion approach in which we synthesize formamidinium iodide (FAI) in-situ in ambient conditions directly near the inorganic template by applying the principle of Le Chatelier and reacting the as-formed FAI with the inorganic template to form the first proof-of-principle devices with this fast, new, low-cost synthesis approach.