Simultaneous Absorption and Near‐Infrared Emission Enhancement of Cr<sup>3+</sup> Ions in MgGa<sub>2</sub>O<sub>4</sub> Spinel Oxide via Anionic F‐Substitution
Leqi Yao, Qianyi Jia, Shijie Yu, Chao Liang, Jianqing Jiang, Qiyue Shao
Abstract
Abstract 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 MgGa 2 O 4 :Cr 3+ phosphors. Accordingly, absorption enhancement as well as emission redshift and broadening are achieved for F‐substituted MgGa 2 O 4 :Cr 3+ (MGOF:Cr 3+ ) 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 (λ max ) of 835 nm and a full width at half maximum of ≈250 nm. Furthermore, MGOF:0.02Cr 3+ has a near‐unity internal quantum efficiency and its emission intensity at 150 °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 λ max of 870 nm. The Cr 3+ local structural alteration with F‐substitution is revealed to account for the outstanding NIR luminescence characteristics of MGOF:Cr 3+ 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.