Lattice-homogenized Br/I alloyed CsPb(Br/I)3 red quantum dots for wide-color-gamut WLEDs

All-inorganic red-emitting CsPbI 3 perovskite quantum dots (PQDs) suffer from cubic-phase instability and iodide ion migration, causing phase separation and emission quenching. This work demonstrates that lattice-level Br/I homogenization is essential for stable red emission, rather than physical blending or surface doping. Through systematic compositional screening of CsPb(Br/I) 3 solid solutions, CsPbBr 1 I 2 is identified as the optimal composition, delivering pure emission at 640 nm. Br incorporation strengthens Pb–Br bonds, passivates halide vacancies, and synergistically suppresses phase transitions and ion migration. As a result, CsPbBr 1 I 2 PQDs exhibit an ultralong fluorescence lifetime of 288 ns and retain over 70% of initial photoluminescence (PL) intensity under combined heat, water immersion, and light stresses, whereas control samples retain only 30−40%. A prototype white light-emitting diode (WLED) backlight display fabricated with these PQDs achieves a color gamut covering 127.07% NTSC and 94.88% Rec.2020, delivering vivid, saturated colors. This work provides a reliable compositional regulation strategy and theoretical foundation for perovskite-based wide-color-gamut displays.