Enhanced Stability and Luminescence Efficiency of CsPbBr 3 PQDs via In Situ Growth and SiO 2 Encapsulation in Surface‐Functionalized Mesoporous Silica Nanospheres

Abstract All‐inorganic perovskite quantum dots (PQDs) have garnered significant attention for optoelectronic applications due to their high photoluminescence quantum yield (PLQY), narrow emission linewidths, and tunable bandgaps. However, their inherent instability under environmental conditions and susceptibility to surface defects limit their practical use. In this study, surface‐functionalized mesoporous silica nanospheres (s‐MSNs) are employed as substrates for the in situ nucleation and growth of CsPbBr 3 PQDs within their open pores, achieving a high PQDs loading of up to 28.3%. To further enhance stability and fluorescence efficiency, the composites are encapsulated with an additional SiO 2 shell via hydrolysis of a silicon precursor, forming CsPbBr 3 /s‐MSNs@SiO 2 core–shell nanostructures. The SiO 2 shell not only effectively shields the PQDs from environmental factors—preventing degradation, leakage and aggregation—but also passivates surface defects and promotes efficient radiative recombination, leading to a significant improvement in luminescence efficiency. Consequently, the CsPbBr 3 /s‐MSNs@SiO 2 composites exhibit enhanced stability and achieve a high PLQY of 90.0%, enabling their sufficient use in anti‐counterfeiting applications. This encapsulation strategy offers a promising route to improve the reliability, efficiency, and longevity of PQDs‐based optoelectronic devices.