Photoluminescence Mechanisms of All‐Inorganic Cesium Lead Bromide Perovskites Revealed by Single Particle Spectroscopy

Abstract Metal halide perovskites (MHPs) are promising materials for a range of optoelectronic applications owing to their unique structures and optical properties. The photoluminescence (PL) property of MHPs is crucial for their applications. All‐inorganic MHPs such as CsPbBr 3 , CsPb 2 Br 5 and Cs 4 PbBr 6 , have been widely investigated due to their high PL quantum yield (QY). However, the PL mechanisms of these perovskites still remain controversial and lack a unifying explanation. In this review, we have summarized the recent efforts to reveal the emission process of all‐inorganic cesium lead bromide perovskites nanocrystals (NCs) by utilizing single particle spectroscopy. The recent research advances on the understanding of exciton nature in CsPbBr 3 and PL emission originating from intrinsic point defects or impurity CsPbBr 3 phase in CsPb 2 Br 5 and Cs 4 PbBr 6 are summarized. Understanding the relationship between the structure and associated PL property of MHPs paves the way for their potential applications.