Tunable Luminescence in LiSc1-yGayW2O8:Cr3+ Phosphors for LED Applications

Achieving emission peaks in the near-infrared II regions (NIR II) and tunable near-infrared (NIR) emission is still a huge challenge in the development of NIR phosphors. Here, a series of LiSc1-yGayW2O8:Cr3+ phosphors are reported based on crystal engineering, whose luminescence can be tuned from NIR-II to NIR I. LiScW2O8:Cr3+ possesses an ultra-wide emission in the range of 850-1400 nm with peak at 1069 nm and a full width at half maximum (FWHM) of 225 nm and the main emission light is located in the NIR-II region. Introducing Ga3+ into LiScW2O8:Cr3+ to form LiSc1-yGayW2O8:Cr3+, the emission spectrum is blueshifted, which better aligns with the characteristic absorption lines of most functional groups. Additionally, the intensity of emission and thermal stability are also improved. The NIR phosphor-converted light-emitting diodes (pc-LED) device is prepared by using the optimized LiSc0.5Ga0.5W2O8:0.12Cr(3+) phosphor and green chip, and different characteristic absorptions are detected by measuring the NIR absorption of water and ethanol with the prepared pc-LED as a radiation source. These results indicate that the ultra-wide near-infrared luminescence of LiSc1-yGayW2O8:xCr(3+) holds potential for applications in non-destructive analysis.