Highly Efficient Green‐to‐Yellowish‐Orange Emitting Eu2+‐Doped Pyrophosphate Phosphors with Superior Thermal Quenching Resistance for w‐LEDs

Abstract

AbstractHighly efficient green/yellowish‐orange phosphors with low thermal quenching behavior are urgently required to improve the luminescence efficiency, color stability, and color rendering of phosphor‐converted white light emitting diodes (w‐LEDs). Herein, a novel green Cs2BaP2O7:0.01Eu2+ phosphor with high luminescence efficiency (82.7%) and thermal quenching behavior (92.5% at 423 K) is reported. Besides, a further luminescence improvement in the quantum yield (98.9%) and thermal quenching resistance (120% at 448 K) is successfully achieved in green/yellowish‐orange color‐tunable Cs2MP2O7:0.01Eu2+ (M = Ba, Sr, and Ca) phosphors. Surprisingly, these green/yellowish‐orange Cs2MP2O7:0.01Eu2+ (M = Ba, Sr, and Ca) phosphors even have a prior advantage over the commercial green β‐SiAlON:Eu2+ and yellow YAG:Ce3+ phosphors. The corresponding spectral adjustment and thermal stability mechanisms are revealed, related to the optimization of local lattice symmetry. The prototype w‐LEDs exhibit warm white light with CIE color coordinate at (0.337, 0.322). The color rendering index, corrected color temperature, and luminescence efficiency can reach 92.6, 4044 K, and 152.56 lm W−1, respectively. In general, the as‐reported green/yellowish‐orange Eu2+‐doped pyrophosphate phosphors are promising candidates in the future high‐quality w‐LEDs applications. The proposal of local lattice symmetry modulation can provide a new approach to exploit novel phosphors with excellent thermal quenching resistance.