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

Abstract In this study, Cr 3+ ‐doped and Mn 4+ ‐Cr 3+ co‐doped double perovskite fluoride phosphors K 2 LiGaF 6 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 Mn 4+ on the NIR luminescence properties of Cr 3+ is studied. Compared with the Cr 3+ single‐doped phosphor, Mn 4+ , and Cr 3+ co‐doped K 2 LiGaF 6 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 Cr 3+ ‐doped fluoride NIR phosphors.