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

Abstract 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 CsPbBr 3 QDs embedded in silica matrices (CsPbBr 3 /silica composites). The FPT enables epitaxial growth of BaF 2 shells on CsPbBr 3 surfaces via thermally driven fluoride ion diffusion, which passivates surfaces and suppresses thermal‐ and light‐induced defects in CsPbBr 3 . The FPT‐treated CsPbBr 3 /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 CsPbBr 3 /silica composites represent the most stable CsPbBr 3 emitters under light aging. Theoretical calculations reveal that the BaF 2 shells elevate the formation energy of bromine vacancies and anchor [PbBr 6 ] octahedra in CsPbBr 3 , 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 CsPbBr 3 QDs for high‐performance LCD applications.