Mn ²⁺ ‐Doped Perovskite Nanocrystals Embedded in Glass With Green–Red Emissions for Wide‐Gamut White Light‐Emitting Diodes

We demonstrate tunable green–red dual‐band photoluminescence (PL) in glasses containing Mn 2+ ‐doped CsPbBr 3 nanocrystals (NCs) and evaluate their application in white light‐emitting diodes (WLEDs). Green emission from CsPbBr 3 NCs was achieved by controlling the competitive growth between CsPbBr 3 and Cs 4 PbBr 6 crystals. Red emission originates from energy transfer from CsPbBr 3 excitons to Mn 2+ ions. The relative PL intensity ratio of red to green emission ( I Mn ​/ I Ex ​) reached values as high as 7.19, while the maximum photoluminescence quantum yield (PLQY) was 44 ± 1% following heat treatment at 560°C for 15 h. The glass exhibited excellent spectral stability at 175°C and after immersion in water for 30 days. A prototype WLED fabricated using a monolithic glass plate and a 450 nm blue LED chip produced high‐quality white light with CIE coordinates of (0.338, 0.324) and a wide color gamut. The color converter also showed excellent photostability, retaining ∼90% of its initial luminous efficacy after 100 h of operation. These results highlight the strong potential of Mn 2+ ‐doped perovskite NC glasses for practical WLED applications.