Interstitial oxygen defect inducing near-infrared luminescence in Ca3La2W2O12 phosphor

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 Ca 3 La 2 W 2 O 12 (CLWO) successfully achieved a NIR emission and high thermal stability. Under 350 nm excitation, the optimal CLWO:0.2 %Bi 3+ 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 %Bi 3+ phosphor shows a high PLQY of 48.84 % and excellent thermal stability (I 420 K /I 300 K = 69.09 %). A NIR phosphor-converted LED (pc-LED) based on a Ca 3 La 2 W 2 O 12 :Bi 3+ (CLWO:Bi 3+ ) 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.