In‐situ Post‐Synthetic Treatment of CsPbBr3 Perovskite Nanocrystals in Nanoporous Silica Microspheres

Comprehensive Summary Inorganic lead halide perovskite (LHP) nanostructures, represented by formula CsPbX 3 (X = Cl, Br, I), have garnered considerable interest for their exceptional optical properties and diverse applications. Despite their potential, challenges such as environmental degradation persist. In‐situ synthesis within protective materials pores is a promising way to address this issue. However, confining perovskite nanostructures into porous matrices during the synthesis can limit their photoluminescence quantum yield (PL QY) and tunability of optical properties. Various post‐treatment approaches exist to improve the properties of LHP and achieve their desired functionalities, but these strategies have not been explored for LHP confined in mesoporous matrices. Here, we demonstrate the efficacy of in‐situ post‐synthetic treatments to improve the optical properties of CsPbBr 3 nanocrystals grown in nanoporous silica microspheres. Surface passivation with Br – ion‐containing precursors boosts PL QY, while anion‐assisted cation doping with Mn 2+ ions introduces a new PL band. The adjustment of precursor amount and doping duration enables precise control over the optical properties of LHP, while additional coating with a SiO 2 shell enhances their stability in polar solvents, expanding the potential applications of these composites.