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

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 CsPbBr3, CsPb2Br5 and Cs4PbBr6, 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 CsPbBr3 and PL emission originating from intrinsic point defects or impurity CsPbBr3 phase in CsPb2Br5 and Cs4PbBr6 are summarized. Understanding the relationship between the structure and associated PL property of MHPs paves the way for their potential applications.