Cr<sup>3+</sup>-Doped NIR Phosphor with Well-Defined Stokes/Anti-Stokes Phonon Sidebands for a Ratiometric Thermometer and Thermally Stable NIR LEDs
Jianhui Wang, Zeyu Lyu, Guan Peng, Dashuai Sun, Sida Shen, Zheng Lu, Lixuan Wang, Hanwei Zhao, Shuai Wei, Hongpeng You
Abstract
Near-infrared (NIR) luminescent materials have attracted enormous attention for the cutting-edge applications in optical thermometer and NIR LEDs. Herein, we report a highly efficient Cr 3+ -doped NIR phosphor, BaAl 4 Sb 2 O 12:0.024Cr 3+ (BASO:Cr 3+ ), with 91% internal quantum efficiency. Strikingly, BASO:Cr 3+ possesses rare and typical Stokes/anti-Stokes phonon sidebands. The Stokes phonon sideband decreases with increasing temperature, while the anti-Stokes one increases considerably. Consequently, this inverse change has gifted the BASO:Cr 3+ with excellent thermal stability, which maintains 118% of the room temperature emission intensity at 423 K. In addition, the well-defined Stokes/anti-Stokes phonon sidebands are applied to a ratiometric thermometer with a maximum relative sensitivity factor of 3.12% K –1 at 150 K. Finally, a well-performing NIR LED is made with BASO:Cr 3+, which can be used for nondestructive testing, information encryption, and night vision. Our findings not only shed light on the emission behavior of Cr 3+ but also point out an avenue for thermally stable NIR phosphors and a sensitive optical thermometer.