A broadband near‐infrared Sc <sub>1</sub> <sub>−</sub> <i> <sub>x</sub> </i> (PO <sub>3</sub> ) <sub>3</sub> : <i>X</i> Cr <sup>3+</sup> phosphor with enhanced thermal stability and quantum yield by Yb <sup>3+</sup> codoping
Ting Yu, Haoyang Sheng, Shenghai Chen, Jian Yuan, Tingting Deng, Ming Wu, Yue Guo, Qingguang Zeng
Abstract
Abstract Broadband near‐infrared (NIR) phosphors converted light‐emitting diodes (pc‐LEDs) have attracted tremendous attention for their great potential in NIR spectroscopy applications. Herein, we report on the photoluminescence (PL) properties of Cr 3+ ‐doped Sc(PO 3 ) 3 , which exhibits a broadband NIR emission centered at 900 nm with a full width at half‐maximum (FWHM) of 161 nm upon excitation at 480 nm. In terms of the examination of spectroscopic parameters, we find that Cr 3+ ions occupy a weak crystal field site ( Dq / B = 1.94) in the Sc(PO 3 ) 3 host with a stronger electron–phonon coupling (Huang‐Rhys factor, S = 5.5), which results in a serious thermal quenching and a low internal quantum efficiency (IQE). Thermal stability and IQE of phosphors can be substantially enhanced by the introduction of Yb 3+ ions. In the light of the analysis of excited‐state dynamics, we demonstrate that the enhancement mechanism is ascribed to the efficient Cr 3+ →Yb 3+ energy transfer from the thermal sensitive Cr 3+ centers to the thermal stable Yb 3+ emitters. An NIR pc‐LED device has been finally fabricated by the combination of a blue‐emitting chip and a Cr 3+ /Yb 3+ codoped Sc(PO 3 ) 3 phosphor whose potential application for broadband NIR pc‐LEDs is also discussed.