Fast, tunable and reversible anion-exchange in CsPbBr3 perovskite nanocrystals with hydrohalic acids

Abstract

Anion exchange in colloidal caesium–lead–halide perovskite nanocrystals (NCs) (CsPbX₃, X = Cl, Br, I) is a highly efficient protocol to tune their chemical composition and optoelectronic properties. Here, we report for the first time the use of hydrohalic acids (HX; X = Cl and Br) as precursors for anion exchange, which can be an efficient way to control the composition and optical properties of CsPbBr₃ perovskite nanocrystals (NCs). In this work, it is demonstrated that a facile and efficient anion-exchange approach is implemented to tune the optical properties of CsPbX₃ perovskite NCs via a simple post-synthetic modification with hydrohalic acids. For the Cl-exchanged NCs, back exchange can be established in terms of variation in halide composition to retain the photoluminescence (PL) properties of parent CsPbBr₃ perovskite NCs to the maximum extent. Along with hydrohalic acids, various other halide sources have been used to achieve tunable anion-exchange of CsPbBr₃ NCs. Treatment with hydrohalic acids allows for fast and feasible anion-exchange of CsPbX₃ perovskite NCs which makes them stand out from the rest of the halide sources. Importantly, this work presents a simple, feasible, reproducible synthetic route to control halide exchange in metal halide perovskite NCs with various optoelectronic properties.