Multichromism in Halide Perovskites

Abstract The flexibility and adaptability of halide perovskites position them as a promising material for a variety of cutting‐edge technologies. In addition to their primary applications in photovoltaics and light‐emitting diodes, they have recently garnered interest for potential use in switchable technologies, such as smart windows, switchable photovoltaics, memory devices, neuromorphic computing, and sensors. This interest stems from these switchable properties, which allow them to alter color or other physical properties in response to external stimuli like heat, electric fields, light, pressure, and moisture. This review investigates their switching properties and examines their practical applications across a range of emerging chromic technologies. An in‐depth analysis of the mechanisms of reversibility, switchable optical and electrical properties, as well as the chemical and structural transformations these materials undergo is also presented. Furthermore, they are categorized based on their unique switching mechanisms. To assist the research community in developing new multichromic halide perovskite designs, several essential criteria are outlined for effective switchable materials. Lastly, the current challenges faced by these emerging materials are discussed, and a perspective on future developments and potential breakthroughs in this promising research area is offered.