In Situ Growth of MAPbBr₃ Quantum Dots in Crosslinked PMMA for Wide‐Gamut Display Backlights

Methylammonium lead bromide perovskite (MAPbBr 3 ) quantum dots (QDs) have emerged as promising candidates for next‐generation optoelectronic applications owing to their exceptional photoluminescent properties. However, their practical applications face significant challenges due to inherent instability issues. Herein, a solvent‐induced in situ crystallization method is presented to encapsulate MAPbBr 3 QDs within a crosslinked (cl‐) polymethyl methacrylate (PMMA) network. This innovative approach eliminates environmental concerns associated with traditional solvent evaporation methods while enabling uniform dispersion and stabilization of perovskite QDs within the crosslinked polymer matrix. The effects of preparation conditions are systematically investigated on the optical performance of the composite materials. Notably, UV irradiation is found to significantly enhance the luminescent performance. The optimized MAPbBr 3 @cl‐PMMA exhibits outstanding optoelectronic performance, featuring a narrow emission profile (full width at half maximum: 24.6 nm), high optical transmittance (91%), and an impressive photoluminescence quantum yield of 98.3%. Benefiting from the protective crosslinked polymer matrix, the composite demonstrates exceptional stability. Furthermore, by integrating MAPbBr 3 @cl‐PMMA film with commercial K 2 SiF 6 :Mn 4+ (KSF) red phosphor, a liquid crystal display (LCD) backlight device achieving a wide color gamut of 122.7% National Television System Committee (NTSC) 1953 standard is fabricated. This environmentally friendly and scalable synthesis method offers a promising pathway for large‐area manufacturing and practical optoelectronic applications.