Ferroelasticity in Halide Perovskites Affects Electro‐Optical Properties through Facet Stability

Abstract Advancements in ferroic materials center upon understanding domain structures and their boundaries. This study innovates by directing the growth of lead halide perovskite microcrystals from the gas phase onto pre‐chosen substrates, thereby inducing an interfacial strain that prompts ferroelasticity‐driven structural transformation. A method of ferroelastic engineering in vapor‐grown perovskite heterostructures is thus unveiled, revealing ordered domain patterns of bright crystals with contrasting electro‐optical properties. In the case of the frustrated halide perovskite crystals, the strain is relaxed by the formation of alternating crystallographic twin domains. In the demonstrated orthorhombic system, these domains alternate between (110) and (002) orientation, with a (112) domain boundary. Perovskite ferroelastic effect with facet stability is correlated, attributed to the exposure of lower surface energy terminations, promoting the material's stability and efficiency. This findings result from direct electrical measurements, which pave the way for the tailored design of ferroic materials, optimizing their optoelectronic characteristics for enhanced device performance.