Epitaxial CsPbBr₃ Perovskite – Cs₃Cu₂Br₅ Ternary Metal Halide Nanoheterostructures

Designing epitaxial nanoheterostructures of metal halide perovskites with other semiconductor materials offers a way to tune their optical properties and charge carrier dynamics. However, achieving an epitaxial interface between them presents a significant challenge due to the differences in their bonding nature, growth kinetics, and lattice mismatch. We synthesized a colloidal epitaxial nanoheterostructure with a pseudo type-II band alignment comprising CsPbBr₃ perovskite and Cs₃Cu₂Br₅ ternary metal halide. A hot-injection synthesis route was developed that offers a common reaction pathway for the formation of both kinds of nanocrystals, facilitating the heteronucleation of Cs₃Cu₂Br₅ on CsPbBr₃ nanocubes through shared Cs⁺ and Br^- sublattices. The crystallographic planes that align across the interface, having minimum lattice mismatch, establish the epitaxial relationship between the constituting counterparts of the nanoheterostructure. This study presents a method for utilizing the Cs and Br sublattices to create an epitaxial interface, enabling development of various combinations of perovskite-semiconductor nanoheterostructures.