Orange phosphor Li₂SrSiON₂:Eu2+ for blue light chip based warm white LEDs

摘要

Oxynitride Li₂SrSiON₂ was synthesized by introducing N3? into the Li₂SrSiO₄ lattice, which is suitable for Eu2+ doping. It crystallizes in an trigonal structure with the space group of P3₁21 (152) and cell parameter a = b = 5.0131(0) ?, c = 12.4270(1) ? and V = 270.46 ?3. Under blue light (450 nm) excitation, the representative sample Li₂Sr_0.98SiON₂:0.02Eu2+ exhibits a bright broad band orange emission peaking at 586 nm with an external quantum efficiency of 52.7%. Its emission intensity at 150 °C remained 78% of that measured at 25 °C. Warm white light-emitting diode 1 (W-LED1) was prepared by combining a blue LED chip and LSSON:0.02Eu2+. High color rendering index (R_a ～ 90) warm W-LED2 was fabricated by combing a blue light chip, BaSi₂O₂N₂:Eu2+, and Li₂Sr_0.98SiON₂:0.02Eu2+. The chromaticity coordinate and correlated color temperature (CCT) of W-LED2 are (0.3625, 0.3539) and ～4386 K, respectively. Excellent optical properties allow it to be an attractive orange phosphor for warm W-LEDs.