Interstitial Oxygen Defect Inducing Near-Infrared Luminescence in Ca3La2W2O12 Phosphor
Abstract
Self-activated near-infrared (NIR) phosphors have recently gained extensive attention in special illumination and biomedical applications owing to its non-toxicity, inexpensiveness and especially undoped luminescence center ions. However, high photoluminescence quantum yields (PLQY) and thermal stability remain challenges for NIR-emitting phosphors. In this study, a self-activated phosphor Ca3La2W2O12 (CLWO) successfully achieved a NIR emission and high thermal stability. Under 350?nm excitation, the optimal CLWO:0.2%Bi3+ phosphor shows a narrowband emission in the range of 650-800?nm and a full width of half maximum (FWHM) of 36?nm. Mechanism studies demonstrate that the interstitial oxygen within CLWO host can work as the luminescence center, and enables self-activated emission in NIR waveband. Moreover, CLWO:0.2%Bi3+ phosphor shows a high PLQY of 48.84% and excellent thermal stability (I420 K/I300 K = 69.09%). A NIR phosphor-converted LED (pc-LED) based on a Ca3La2W2O12:Bi3+ (CLWO:Bi3+) phosphor is fabricated on a 350?nm LED chip, demonstrating its potential in NIR night-vision monitoring. This work certainly designs novel insights for outstanding thermal stability of self-activated phosphors and develops new research avenues for self-activated NIR LED light sources applications.