Ultrastable Perovskite Nanocrystal/Silica Composites with Green Emission Approach Rec. 2020 Standard via an Alloying Strategy

Achieving narrow green emission, matching the Rec. 2020 standard, remains a challenge for all-inorganic perovskite nanocrystals due to halide segregation. Herein, we report a Zn/Pb alloying strategy to achieve ultrastable CsZn x Pb 1– x Br 2.5 I 0.5 nanocrystals within SiO 2 matrices (CsZn 0.4 Pb 0.6 Br 2.5 I 0.5 /SiO 2 composites) with tunable green emission. Introducing Zn 2+ into mixed-halide perovskite nanocrystals effectively suppresses halide segregation and reduces the defect density. Optimized CsZn 0.4 Pb 0.6 Br 2.5 I 0.5 /SiO 2 composites exhibit a narrow green emission at 536 nm with a full-width at half-maximum (fwhm) of 23 nm and exceptional water stability (retaining 100% intensity after 240 h). X-ray photoelectron spectroscopy and positron annihilation spectroscopy reveal that Zn 2+ incorporation strengthens cation-halide interactions and lowers the vacancy concentration, thereby elevating the activation energy for halide migration. A white LED fabricated with these composites achieves 93% Rec. 2020 color-gamut coverage, surpassing commercial β-Sialon-based LED (81%). This work provides an effective approach to synthesize mixed-halide perovskite nanocrystals for high-performance wide-color-gamut displays.