Broadband NIR‐II Emission Generated by Tetrahedral Cr<sup>3+</sup>/Cr<sup>4+</sup> in SrLaGa<sub>3</sub>O<sub>7</sub>
Xiao‐Na Shen, Zhijian Li, Yuguo Yang, Yuanyuan Zhang, Bing Liu, Huajian Yu, Cheng‐Cheng Qiu, Xianshun Lv, Rui Zhang, Qiang Shi, Huadi Zhang, Xuping Wang
Abstract
Abstract Broadband near‐infrared (NIR) phosphors have garnered significant attention due to their potential applications in phosphor‐concerted NIR light‐emitting diodes (pc‐NIR‐LEDs). Cr 3+ ‐doped NIR phosphors are particularly intriguing because of their broad NIR emission and high efficiency. However, reports on Cr 3+ ‐doped NIR‐II (900–1700 nm) phosphors are scarce. In this study, a novel Cr 3+ ‐doped SrLaGa 3 O 7 NIR‐II phosphor is presented, where the Cr 3+ ions are located at tetrahedral sites. The full width at half maximum (FWHM), peak wavelength, internal quantum efficiency (IQE), and thermal activation energy (Δ E ) for the synthesized SrLaGa 3 O 7 :0.9%Cr 3+ phosphor are 194 nm, 1167 nm, 76.12%, and 0.269 eV, respectively. The substitution of Sc 3+ for Ga 3+ enhances the luminescence performance, and the 0.9%Cr 3+ /3%Sc 3+ co‐doped SrLaGa 3 O 7 phosphor exhibits a peak wavelength of 1208 nm, an IQE of 92.78%, and a Δ E of 0.285 eV. Furthermore, the sintering process in the air induces a transition from Cr 3+ to Cr 4+ , resulting in the formation of SrLaGa 3 O 7 :0.9%Cr 4+ phosphor, which has a peak wavelength of 1270 nm and an FWHM of 305 nm. The potential application of the 0.9%Cr 3+ /3%Sc 3+ co‐doped SrLaGa 3 O 7 phosphor in pc‐NIR‐LEDs is also evaluated.