Simultaneous Absorption and Near-Infrared Emission Enhancement of Cr3+ Ions in MgGa2O4 Spinel Oxide via Anionic F-Substitution

Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) are newly emerging broadband NIR light sources. However, the lack of high-performance NIR-emitting materials limits their popularization. Herein, an anionic F-substitution strategy is presented to regulate the light absorption and emission of MgGa2O4:Cr3+ phosphors. Accordingly, absorption enhancement as well as emission redshift and broadening are achieved for F-substituted MgGa2O4:Cr3+ (MGOF:Cr3+) phosphors, simultaneously with high efficiency and excellent thermal stability. Upon blue light excitation, the MGOF:0.02Cr(3+) phosphor exhibits a broadband NIR emission (650-1200 nm) with a peak wavelength (lambda(max)) of 835 nm and a full width at half maximum of approximate to 250 nm. Furthermore, MGOF:0.02Cr(3+) has a near-unity internal quantum efficiency and its emission intensity at 150 degrees C maintains 94% of the initial value. A record external quantum efficiency of 60.6% is further achieved for MGOF:0.08Cr(3+) with a redshifted lambda(max) of 870 nm. The Cr3+ local structural alteration with F-substitution is revealed to account for the outstanding NIR luminescence characteristics of MGOF:Cr3+ in view of systematic structural characterization and spectroscopic analysis. A broadband NIR pc-LED device with good optical performance is fabricated and its application in semiconductor wafer inspection is demonstrated. This study initiates a new way to design high-performance NIR phosphors.