High-Efficiency Violet-Emitting All-Inorganic Perovskite Nanocrystals Enabled by Alkaline-Earth Metal Passivation

Cesium lead halide perovskite nanocrystals (NCs) have emerged as promising luminescent materials for a range of applications. However, the creation of highly luminescent violet-emitting CsPbCl3 NCs mostly relies on doping of a limited number of small-sized metal ions or post-synthetic surface treatment of NCs. Alkaline-earth (AE) metals (e.g., Ca2+, Sr2+, and Ba2+) have been proposed to be able to substitute Pb2+ in halide perovskites, yet it remains incompletely understood whether AE metal ions can be incorporated into the perovskite lattice or can be merely situated at the surface. Here, we explore the possibility of using AE metal ions for the suppression of the formation of trap centers, which leads us to develop a one-pot synthetic passivation strategy to boost the violet-emitting efficiency of CsPbCl3 NCs through the creation of a Ca2+/Sr2+ involved passivation layer. The photoluminescence quantum yield of violet emission reaches 77.1% by incorporating an optimal amount of Ca2+. A wide range of opti...