Suppressing Thermal‐ and Light‐Induced Photoluminescence Quenching in Perovskite Quantum Dots Through Fluoride Post‐Treatment

Perovskite quantum dots (QDs) hold promise for next-generation display applications but suffer from stability challenges, particularly thermal- and light-induced photoluminescence (PL) quenching. Here, a fluoride post-treatment (FPT) strategy is developed to address this challenge for CsPbBr₃ QDs embedded in silica matrices (CsPbBr₃/silica composites). The FPT enables epitaxial growth of BaF₂ shells on CsPbBr₃ surfaces via thermally driven fluoride ion diffusion, which passivates surfaces and suppresses thermal- and light-induced defects in CsPbBr₃. The FPT-treated CsPbBr₃/silica composites exhibit a high PL quantum yield of 94.5%, a complete PL recovery after a thermal cycling (up to 403 K), and retain 95.6% of their initial PL intensity after 1055 h with intense blue light irradiation (350 mW cm^-2). To the best of the knowledge, these FPT-treated CsPbBr₃/silica composites represent the most stable CsPbBr₃ emitters under light aging. Theoretical calculations reveal that the BaF₂ shells elevate the formation energy of bromine vacancies and anchor [PbBr₆] octahedra in CsPbBr₃, thereby inhibiting defect generation. A liquid crystal display (LCD) equipped with these composites achieves a 120% national television system committee color gamut. This work provides a robust route to stabilize CsPbBr₃ QDs for high-performance LCD applications.