Impeding anion exchange to improve composition stability of CsPbX_3(X= Cl,Br) nanocrystals through facilely fabricated Cs_4Pb_6 shell

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, CsPb X_3(X = Cl, Br) NCs are coated with Cs_4PbX_6 shell to impede anion exchange and reduce anion mobility. The Cs_4PbX_6 shell is facily fabricated on CsPbX_3 NCs through high temperature injection method.Anion exchange experiments demonstrate that the Cs_4 PbX_6 shell completely encapsulates CsPbX_3 NCs and greatly improves the composition stability of CsPbX_3 NCs. Moreover, our work also sheds light on the potential design approaches of various heterostructures to expand the application of CsPbM_3(M = Cl, Br, I) NCs.