Hydrothermal synthesis of ZnGa 2 O 4 nanophosphors with high internal quantum efficiency for near-infrared pc-LEDs.

NIR luminescent materials have garnered widespread attention because of their exceptional properties, with high tissue penetration, low absorption and high signal-to-noise ratio in the field of optical imaging. However, producing nanophosphors with high quantum yields of emitting infrared light with wavelengths above 1000 nm remains a significant challenge. Here, we prepared a nanoscale ZnGa 2 O 4 : x Cr 3+ , y Ni 2+ phosphor with good luminescence performance in near-infrared emission, which was synthesized via a hydrothermal method and subsequent calcination process. By co-doping with Cr 3+ and Ni 2+ , the ZnGa 2 O 4 phosphor shows a strong broadband emission of 1100-1600 nm in the second near-infrared (NIR-II) region, owing to the energy transfer from Cr 3+ to Ni 2+ with an efficiency up to 90%. Meanwhile, a near-infrared phosphor-conversion LED (NIR pc-LED) device is fabricated based on the ZnGa 2 O 4 :0.8%Cr 3+ ,0.4%Ni 2+ nanophosphor, which has under 100 mA input current, an output power of 23.99 mW, and a photoelectric conversion efficiency of 7.53%, and can be effectively applied in imaging and non-destructive testing. Additionally, the intensity ratio of I Ni / I Cr of ZnGa 2 O 4 :0.8% Cr 3+ ,0.4%Ni 2+ with its high sensitivity value of 4.21% K -1 at 453 K under 410 nm excitation, indicates its potential for thermometry application.