Nanoconfined Synthesis of CsPbBr₃ Quantum Dots: Enhanced Stability, Tunable Luminescence, and Sensitive Sensing Application

The integration of metal halide perovskite quantum dots (PQDs) into sensing technologies has been hindered by challenges in balancing environmental stability and sensing sensitivity. In this work, mesoporous silica nanoparticles (MSNs) with tunable pore sizes were employed as nanoconfinement reactors to synthesize size-controlled CsPbBr₃ PQDs (3.0-12.0 nm). The nanoconfined environment facilitated the selective growth of pure CsPbBr₃ phases, avoiding unwanted Cs₄PbBr₆ formation. The resulting nanoconfined PQDs, CsPbBr₃@MSN, exhibited tunable emission from blue to green (470 to 515 nm), a high quantum yield (36.8%), and enhanced stability. Moreover, the PQD composites demonstrated exceptional performance in detecting the pesticide dicloran, achieving a detection limit of 0.16 μM, far below China's national standard requirement (34.0 μM). The detection mechanism involved competitive adsorption and phase transitions from the cubic CsPbBr₃ phase to the quasi-2D CsPb₂Br₅ phase. The porous MSN structure maintained efficient mass and energy transfer, ensuring both stability and sensitivity. Beyond sensing, these nanocomposites show potential for applications in anticounterfeiting and fingerprint recognition. This study highlights nanoconfinement as a powerful strategy for developing robust, high-performance PQD-based fluorescent sensors.