Impeding anion exchange to improve composition stability of CsPbX3 (X = Cl, Br) nanocrystals through facilely fabricated Cs4Pb X6 shell**Project supported by the National Natural Science Foundation of China (Grant Nos. 11474018, 61704007, and 61575019), the National Key Research and Development Program of China (Grant No. 2017YFB0404501), the Fundamental Research Funds for the Central Universities, China (Grant No. 2017RC034), and

Abstract

Inorganic lead halide perovskite nanocrystals (NCs) with superior photoelectric properties are expected to have excellent performance in many fields. However, the anion exchange changes their features and is unfavorable for their applications in many fields. Hence, impeding anion exchange is important for improving the composition stability of inorganic lead halide perovskite NCs. Herein, CsPbX3 (X = Cl, Br) NCs are coated with Cs4PbX6 shell to impede anion exchange and reduce anion mobility. The Cs4PbX6 shell is facily fabricated on CsPbX3 NCs through high temperature injection method. Anion exchange experiments demonstrate that the Cs4PbX6 shell completely encapsulates CsPbX3 NCs and greatly improves the composition stability of CsPbX3 NCs. Moreover, our work also sheds light on the potential design approaches of various heterostructures to expand the application of CsPbM3 (M = Cl, Br, I) NCs.