Broadband near-infrared (NIR)-emitting phosphors are key for next-generation smart NIR light sources based on blue LEDs. To achieve excellent NIR phosphors, a strategy of enhancing crystallinity, modifying micromorphology, and maintaining the valence state of Cr³⁺ in Ca₃Sc₂Si₃O₁₂ garnet (CSSG) is proposed. By adding fluxes and sintering in a reducing atmosphere, the internal quantum efficiency (IQE) is greatly enhanced to 92.3%. The optimized CSSG:6%Cr³⁺ exhibits excellent thermal stability (maintaining 97.4% of room temperature NIR emission at 150 °C). The fabricated NIR-LED device emits a high optical power of 109.9 mW at 520 mA. The mechanism for optimization is investigated, and an application of the NIR-LED light source is demonstrated.

Zhenwei Jia, Chenxu Yuan, Yongfu Liu, Xiao-Jun Wang, Peng Sun, Lei Wang, Haochuan Jiang, Jun Jiang