Vapor-Phase Deposition of CsPbBr₃ Shells on Iodide-Rich Perovskite Cores in SiO₂ for Efficient and Robust Red...

While high-temperature solid-phase confined synthesis has established itself as a viable approach for producing ultra-stable halide perovskite nanocrystals (NCs), the photoluminescence quantum yield (PLQY) of the resulting red-emitting NCs, whether pure-iodide or mixed-halide, remains unsatisfactory. In this work, we introduce a high-temperature vapor-phase deposition for the controlled synthesis of CsPbI₃/CsPbBr₃ and CsPb(Br/I)₃/CsPbBr₃ heterostructure NCs encapsulated within a robust SiO₂ matrix. This method spatially separates the CsPbBr₃ shell precursor from the preformed iodine-rich core in the vapor phase, effectively suppressing undesirable halide diffusion during high-temperature processing at 700°C. By leveraging the strong Br─Cs/Pb interactions, the CsPbBr₃ vapor promotes preferential interfacial deposition on CsPbI₃ or CsPb(Br/I)₃ cores. The resulting NCs display highly efficient red emission, achieving a PLQY as high as 85%. Furthermore, benefiting from the dual protection of the SiO₂ matrix and the heterostructure, these red-emitting materials exhibit outstanding environmental stability while retaining their high performance.