Robust CsPbBr3@SiO2 Nanocrystals with Controlled Shell Growth for Stable High-Resolution X-ray Scintillation Imaging

Abstract

The development of high-light-yield scintillators based on perovskite quantum dots (PQDs) is hindered by their intrinsic instability and aggregation, which severely limits their long-term operational reliability and integration into polymeric matrices. Silica coating has been demonstrated as an effective strategy to enhance the stability of PQDs. However, achieving fast and uniform silica encapsulation on individual nanocrystals remains challenging. Here, we report an efficient ammonia-catalyzed strategy enabling the formation of a dense and uniform silica shell, leading to discrete CsPbBr3@SiO2 core–shell structures with significantly enhanced robustness. The conformal silica coating preserves optical quality, maintaining 87% photoluminescence quantum yield in solution and 75% in film while minimizing aggregation and spectral drift. When incorporated into poly(methyl methacrylate) (PMMA), the resulting CsPbBr3@SiO2@PMMA scintillators deliver a high light yield of ∼26,000 photons MeV–1, a spatial resolution of 16 lp mm–1, and >90% PL retention after 120 days of ambient storage. These combined improvements position silica-encapsulated PQDs as promising emitters for next-generation X-ray scintillation devices.