Wide‐Bandgap Perovskite‐Inspired Materials: Defect‐Driven Challenges for High‐Performance Optoelectronics

Abstract The remarkable success of lead halide perovskites (LHPs) in photovoltaics and other optoelectronics is significantly linked to their defect tolerance, although this correlation remains not fully clear. The tendency of LHPs to decompose into toxic lead‐containing compounds in the presence of humid air calls for the need of low‐toxicity LHP alternatives comprising of cations with stable oxidation states. To this aim, a plethora of low‐dimensional and wide‐bandgap perovskite‐inspired materials (PIMs) are proposed. Unfortunately, the optoelectronic performance of PIMs currently lags behind that of their LHP‐based counterparts, with a key limiting factor being the high concentration of defects in PIMs, whose rich and complex chemistry is still inadequately understood. This review discusses the defect chemistry of relevant PIMs belonging to the halide elpasolite, vacancy‐ordered double perovskite, pnictogen‐based metal halide, Ag‐Bi‐I, and metal chalcohalide families of materials. The defect‐driven optical and charge‐carrier transport properties of PIMs and their device performance within and beyond photovoltaics are especially discussed. Finally, a view on potential solutions for advancing the research on wide‐bandgap PIMs is provided. The key insights of this review will help to tackle the commercialization challenges of these emerging semiconductors with low toxicity and intrinsic air stability.