Structurally Stabilizing and Environment Friendly Triggers: Double‐Metallic Lead‐Free Perovskites

Lead halide perovskite (ABX 3 ) has attracted considerable attention due to its applicability as absorber layers in highly efficient photovoltaic cells. With regard to the lead toxicity, double‐metallic lead‐free perovskite, A 2 B I B III X 6 , in which the neighboring B + and B 3+ sites in the crystal microstructure are alternately occupied by monovalent‐metal and trivalent‐metal cations, is regarded to be a promising alternative to the widely used lead‐based perovskites. This review aims to summarize the recent advances in the new class of A 2 B I B III X 6 double‐metallic lead‐free perovskites. In particular, the electronic structure, synthesis, property, and their applications in devices, for example, photovoltaics, photodetectors, and light emitting diodes, is carefully classified and presented. Notably, the theoretical calculations point out that there is much room toward potential applications for this new class of perovskite materials. The present review provides a holonomic conclusion and opens new perspectives toward realizing higher performance of A 2 B I B III X 6 ‐based devices.