Long term suppression of deep traps in CsPbBr3 nanocrystals by introducing slight lattice distortion

Abstract

CsPbX3 (X = Br, Cl, I) nanocrystals have broad application prospects, due to their high luminescent efficiency and low preparation cost. However, the stability of CsPbBr3 nanocrystals prepared using conventional methods is poor; thus, large-scale applications have not yet been achieved. Currently, most of the methods aimed at improving the stability of CsPbBr3 nanocrystals involve inorganic or organic encapsulation, which makes it challenging to apply them to devices that operate with electrical injection. In this article, we report that CsPbBr3 nanocrystals prepared by the solvent quenching method, without any external encapsulation, can maintain excellent optical properties after long-term storage. Through the studies of temperature-dependent photoluminescence spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy, we have revealed that the nanocrystals prepared by solvent injection quenching method contain slight lattice distortion of the [PbBr]64- cages, which can lead to the formation of shallow trap states while suppressin the formation of deep traps, thereby maintaining excellent optical properties for long time.