Heavy Mn2+ Doped MgAl2O4 Phosphor for High-Efficient Near-Infrared Light-Emitting Diode and the Night-Vision Application

Photoluminescence originated from doped activators in the solid state materials usually faces the challenge of concentration quenching, restricting the further increase of photoluminescence intensity. Herein, a new strategy is demonstrated by the heavy doping Mn2+ into MgAl2O4, leading to the broad-band near-infrared (NIR) emission peaking at approximate to 825 nm with a full width at half maximum of approximate to 125 nm, as well as high internal quantum efficiency of approximate to 53% upon 450 nm laser excitation. Density functional theory calculation and extend X-ray absorption fine structure provide a understanding of Al3+/Mn2+ disorder and Mn2+-Mn2+ aggregation in spinel Mg1-xAl2O4:xMn(2+) with high Mn2+ content, which enables the formation of superexchange coupled Mn-IV(2+)-Mn-VI(2+) pair. The NIR light-emitting diodes fabricated by the 450 nm blue chip and Mg0.50Al2O4:0.50Mn(2+) phosphor gives a high NIR output power of approximate to 78.41 mW under a driven current of 120 mA, and night-vision application as light source in the dark is demonstrated. This work opens new paths for rational design of efficient broad-band NIR emitting phosphor, and also provides new insights into the Mn2+ luminescence and the applications.