Energy Conversion and Transfer in the Luminescence of CeSc3(BO3)4:Cr3+ Phosphor

Lei Chen; Yabing Wu; Qi Liu; Yanguang Guo; Fanghai Liu; Bo Wang; Shizhong Wei

doi:10.3390/ma16031231

Energy Conversion and Transfer in the Luminescence of CeSc₃(BO₃)₄:Cr³⁺ Phosphor

Materials (Basel). 2023 Jan 31;16(3):1231. doi: 10.3390/ma16031231.

Authors

Lei Chen^{1

2

3}, Yabing Wu¹, Qi Liu¹, Yanguang Guo¹, Fanghai Liu¹, Bo Wang⁴, Shizhong Wei²

Affiliations

¹ School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China.
² National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials & Henan Key Laboratory of High-Temperature Structural and Functional Materials, Henan University of Science and Technology, Luoyang 471003, China.
³ Intelligent Manufacturing Institute of HFUT, Hefei 230051, China.
⁴ School of Applied Physics and Materials, Wuyi University, Jiangmen 529020, China.

Abstract

Novel near-infrared (NIR) phosphors are in demand for light-emitting diode (LED) devices to extend their suitability for new applications and, in turn, support the sustainable and healthy development of the LED industry. The Cr³⁺ has been used as an activator in the development of new NIR phosphors. However, one main obstacle for the Cr³⁺-activated phosphors is the low luminescence efficiency due to the spin-forbidden d-d transition of Cr³⁺. The rare-earth (RE) huntite minerals that crystallize in the form of REM₃(BO₃)₄ (M = Al, Sc, Cr, Fe, Ga) have a large family of members, including the rare-earth scandium borates of RESc₃(BO₃)₄. Interestingly, in our research, we found that the luminescence efficiency of Cr³⁺ in the CeSc₃(BO₃)₄ host, whose quantum yield was measured at 56%, is several times higher than that in GdSc₃(BO₃)₄, TbSc₃(BO₃)₄, and LuSc₃(BO₃)₄ hosts. Hereby, the energy conversion and transfer in the luminescence of CeSc₃(BO₃)₄:Cr³⁺ phosphor were examined. The Stokes shift of electron energy conversion within the Cr^{3+ 4}T_2g level for the emission at 818 nm and excitation at 625 nm in CeSc₃(BO₃)₄ host was evaluated to be 3775.1 cm^-1, and the super-large splitting energy of the ²F_5/2 and ²F₇₂ sub-states of the Ce³⁺ 4f¹ state, about 3000 cm^-1, was found in CeSc₃(BO₃)₄ host. The typical electronic thermal vibration peaks were observed in the excitation spectra of CeSc₃(BO₃)₄:Cr³⁺. On this basis, the smallest phonon energy, around 347.7 cm^-1, of the CeSc₃(BO₃)₄ host was estimated. Finally, the energy transfer that is responsible for the far higher photoluminescence of Cr³⁺ in CeSc₃(BO₃)₄ than in other hosts was proven through the way of Ce³⁺ emission and Cr³⁺ reabsorption.

Keywords: CeSc3(BO3)4:Cr3+; energy transfer; huntite; light-emitting diodes (LEDs); near-infrared (NIR) phosphor; photoluminescence.

Grants and funding

This work was supported by the National Natural Science Foundation (21875058), the Natural Science Foundation of Anhui Province (2208085J13), the Major science and technology project of Anhui Province (202103a05020025), the Key Research and Development Program of Anhui Province (202004a05020179), the Science and Technology Achievements Cultivation Project of Intelligent Manufacturing Institute of HFUT (IMIPY2021025), the Research and Development Program of Guangdong Guangyang Electric Appliance Co., LTD (IMIHX2021003), and the Open Foundation of National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials of Henan University of Science and Technology (HKDNM2019015), China.