Broadband NIR phosphor Gd3Lu2Ga3O12: Cr3+, Yb3+ with high thermal stability

Broadband near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have become important as new NIR light sources in NIR spectroscopy and NIR imaging techniques . However, currently developed broadband NIR phosphors commonly suffer from weak emission and poor thermal stability. In this work, a series of Gd 3 Lu 2 Ga 3 O 12 : Cr 3+ phosphors were synthesized via high-temperature solid-state reaction. Under 460 nm excitation, the phosphors exhibit an intense emission spanning from 650 to 1150 nm with a full width at half maximum (FWHM) of 122 nm. After introducing Yb 3+ as a co-dopant, the emission of the phosphor has been broadened greatly. Interestingly, the studied phosphors demonstrate super high thermal stability in a wide temperature range of 35–560 K, with the integrated emission intensity fluctuating within 10 %. At 435 K, the emission intensity of Gd 3 Lu 2 Ga 3 O 12 : 0.03Cr 3+ remains 99.5 % and Gd 3 Lu 2 Ga 3 O 12 : 0.03Cr 3+ , 0.01 Yb 3+ keeps 102.7 % of the initial intensity at room temperature. These NIR phosphors have been encapsulated with a common commercial 460 nm blue LED chip to fabricate a pc-LED device. The NIR output power of the device reaches 23.93 mW@100 mA, with a photoelectric conversion efficiency of 9.81 % at 20 mA current. The applications of the prepared NIR light source in night vision, and bioimaging have been demonstrated. The results show that these Cr 3+ /Yb 3+ doped garnet phosphors can be effectively used in NIR light sources .