Develop Superior Green‐Emitting K‐Rich Eu ²⁺ ‐Activated Nepheline Phosphors for n‐UV‐Driven Pc‐WLEDs

Abstract White light‐emitting diodes (WLEDs) based on near‐ultraviolet (n‐UV) chips exhibit superior spectral stability and health lighting compared to those based on blue chips. Eu 2+ ‐activated nepheline phosphors can efficiently emit broad green light when excited by n‐UV light, showing potential for WLED applications. Traditional high‐temperature solid‐state methods can only control solid solution formation between NaAlSiO 4 and Na 3 K(AlSiO 4 ) 4 , failing to address the issue that Eu 2+ ions occupy two cation sites simultaneously. By utilizing 3A zeolite with a high K/Na ratio as raw material, K‐rich Eu 2+ ‐activated nepheline phosphors are successfully synthesized. This enabled Eu 2+ to solely occupy MO 8 sites and emit broad green light ≈526 nm. The optimal phosphor 3A‐1400: 0.06Eu 2+ exhibited internal and external quantum efficiencies as high as 92.85% and 76.70%, respectively, with emission intensity retention exceeding 86% at 423 K compared to room temperature, demonstrating excellent thermal stability. By combining this green phosphor with commercial blue and red phosphors, phosphor‐converted WLED (pc‐WLED) devices are fabricated on 380 and 395 nm n‐UV chips, yielding warm white light with color rendering indices of 88.0 and 86.8, and luminous efficacies of 71.7 and 55.7 lm W −1 , respectively. These findings underscore the significant potential of the synthesized K‐rich Eu 2+ ‐activated nepheline phosphors in n‐UV‐based pc‐WLEDs.