Broadband near-infrared phosphor SrGe4O9:Cr3+ for NIR-pc-LED applications

The effectiveness of near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) is primarily determined by the NIR phosphors. Unfortunately, there is still a shortage of effective broadband near-infrared luminescent materials which emit NIR light with wavelengths exceeding 800 nm. Herein, Cr3+ doped SrGe4O9 phosphors were prepared by a high-temperature solid-state reaction. The phosphor exhibits a wide NIR emission spanning from 650 to 1250 nm, with the center located at approximately 846 nm. It demonstrates a full width at half maximum (FWHM) of 190 nm and a quantum yield of 66.9 % when excited by the blue light at 442 nm. When subjected to 373 K, the luminescence intensity of the phosphor remains above 80 % of the value at room temperature. The application in night vision and biological imaging have been realized by the prepared SrGe3.99O9: 1%Cr3+ phosphor combined with a commercial 440 nm blue chip.