Synthesis of Highly Photoluminescent All-Inorganic CsPbX3 Nanocrystals via Interfacial Anion Exchange Reactions

All-inorganic cesium lead halide perovskite CsPbX3(X = Cl, Br, I) nanocrystals (NCs) have attracted significant attention owing to their fascinating electronic and optical properties. However, researchers still face challenges to achieve highly stable and photoluminescent CsPbX3NCs at room temperature by the direct-synthesis method. Herein, we synthesize CsPbX3NCs by a facile and environmentally friendly method, which uses an aqueous solution of metal halides to react with Cs4PbBr6NCs via interfacial anion exchange reactions and without applying any pretreatment. This method produces monodisperse and air-stable CsPbX3NCs with tunable spectra covering the entire visible range, narrow photoluminescence emission bandwidth, and high photoluminescence quantum yield (PL QY, 80%). In addition, the chemical transformation mechanism between Cs4PbBr6NCs and CsPbX3NCs was investigated. The Cs4PbBr6NCs were converted to CsPbBr3NCs first by stripping CsBr, and then, the as-prepared CsPbBr3NCs reacted with metal halides to form CsPbX3NCs. This work takes advantage of the chemical transformation mechanism of Cs4PbBr6NCs and provides an efficient and environmentally friendly way to synthesize CsPbX3NCs.Keywords:Cs4PbBr6NCs;CsPbX3NCs;interfacial anion exchange;chemical transformation