Mn4+, Cr3+ Co-doped K2LiGaF6 Phosphors with Bright Near-Infrared Luminescence

In this study, Cr3+-doped and Mn4+-Cr3+ co-doped double perovskite fluoride phosphors K2LiGaF6 are prepared using a simple hydrothermal method. High-efficiency near-infrared (NIR) emission near 762 nm is obtained under blue-light excitation, and the co-doping effect of Mn4+ on the NIR luminescence properties of Cr3+ is studied. Compared with the Cr3+ single-doped phosphor, Mn4+, and Cr3+ co-doped K2LiGaF6 exhibit a sharp increase of 129% in NIR emission, an enhancement in the internal quantum efficiency from 82.5% to 90.0%, and an enhancement in the thermal stability at 425 K from 85.0% to 90.7%. The encapsulated NIR phosphor-converted light-emitting diode device at 300 mA exhibits a photoelectric conversion efficiency of 15.3%. These values exceed most previously reported results. This study provides a new approach for enhancing the luminescence properties of Cr3+-doped fluoride NIR phosphors.