Highly thermal-stable broadband near-infrared emission of Cr3+ doped spinel CdGa2O4 phosphors

Broadband near-infrared phosphor-converted LED (NIR pc-LED) light sources have attracted considerable attentions due to their widespread applications in active security defense, nondestructive detection, and online chemometric analysis. The broadband NIR phosphor, determining the overall performance of NIR pc-LED, is still to be explored. In this study, a series of CdGa 2-x O 4 :xCr 3+ phosphors are prepared by a solid state reaction. Owning to the electron population in 2 E and 4 T 2 energy levels of Cr 3+ ions with an intermediate crystal field, CdGa 2 O 4 :Cr 3+ exhibits a sharp line and broad band overlapped NIR emission spectrum, covering 600–1300 nm with a peak wavelength ( λ max ) of 740 nm and a full width at half maximum (FWHM) of 160 nm. A robust luminescence thermal stability that the NIR emission intensity remains 95 % of the initial level at 423 K is achieved, caused by a weak electron-phonon coupling (EPC) effect. Finally, a prototype NIR pc-LED is fabricated by using the as-obtained broadband NIR phosphor to demonstrate the application for night vision.