Cr³⁺-Yb³⁺-Ni²⁺ Tri-Doped NIR Phosphors with Spectral Output Covering NIR-I and NIR-II Regions

To realize efficient and broadband near infrared (NIR) light in both NIR-I and NIR-II regions, Gd3Mg0.5Al1.5Ga2.5Ge0.5O12 (GMAGG): Cr3+, Yb3+, Ni2+ phosphors are prepared in this study. The effects of Cr3+-Yb3+ co-doping and Cr3+-Yb3+-Ni2+ tri-doping on the luminescence properties are investigated. GMAGG: Cr3+, Yb3+ exhibits high internal quantum efficiency (IQE) of 96.4%, and near-zero thermal quenching (96.5%@423 K) in 650-1100 nm. By constructing energy transfer from Cr3+ to Ni2+, the emission range of GMAGG: Cr3+, Yb3+, Ni2+ is further extended to 650-1700 nm with a high IQE of 28% and good thermal stability (66%@423 K). The NIR LEDs prepared with GMAGG: 0.04Cr(3+), 0.008Yb(3+), and GMAGG: 0.04Cr(3+), 0.008Yb(3+), 0.04Ni(2+) exhibit 57.5 and 8.1 mW at an input current of 100 mA, respectively. The results show that GMAGG: Cr3+, Yb3+, Ni2+ is a promising NIR phosphor for NIR light sources.