Chen Lei, Wu Yabing, Liu Qi, Guo Yanguang, Liu Fanghai, Wang Bo, Wei Shizhong
School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China.
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.
Materials (Basel). 2023 Jan 31;16(3):1231. doi: 10.3390/ma16031231.
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 Cr has been used as an activator in the development of new NIR phosphors. However, one main obstacle for the Cr-activated phosphors is the low luminescence efficiency due to the spin-forbidden d-d transition of Cr. The rare-earth (RE) huntite minerals that crystallize in the form of REM(BO) (M = Al, Sc, Cr, Fe, Ga) have a large family of members, including the rare-earth scandium borates of RESc(BO). Interestingly, in our research, we found that the luminescence efficiency of Cr in the CeSc(BO) host, whose quantum yield was measured at 56%, is several times higher than that in GdSc(BO), TbSc(BO), and LuSc(BO) hosts. Hereby, the energy conversion and transfer in the luminescence of CeSc(BO):Cr phosphor were examined. The Stokes shift of electron energy conversion within the CrT level for the emission at 818 nm and excitation at 625 nm in CeSc(BO) host was evaluated to be 3775.1 cm, and the super-large splitting energy of the F and F sub-states of the Ce 4f state, about 3000 cm, was found in CeSc(BO) host. The typical electronic thermal vibration peaks were observed in the excitation spectra of CeSc(BO):Cr. On this basis, the smallest phonon energy, around 347.7 cm, of the CeSc(BO) host was estimated. Finally, the energy transfer that is responsible for the far higher photoluminescence of Cr in CeSc(BO) than in other hosts was proven through the way of Ce emission and Cr reabsorption.
新型近红外（NIR）荧光粉对于发光二极管（LED）器件来说是有需求的，以扩展其对新应用的适用性，进而支持LED产业的可持续健康发展。Cr已被用作新型近红外荧光粉开发中的激活剂。然而，Cr激活荧光粉的一个主要障碍是由于Cr的自旋禁戒d-d跃迁导致发光效率低。以REM(BO)（M = Al、Sc、Cr、Fe、Ga）形式结晶的稀土（RE）钙钛矿矿物有一大类成员，包括RESc(BO)的稀土钪硼酸盐。有趣的是，在我们的研究中，我们发现CeSc(BO)基质中Cr的发光效率（其量子产率测量为56%）比GdSc(BO)、TbSc(BO)和LuSc(BO)基质中的高几倍。因此，对CeSc(BO):Cr荧光粉发光中的能量转换和转移进行了研究。在CeSc(BO)基质中，对于818 nm发射和625 nm激发，CrT能级内电子能量转换的斯托克斯位移经评估为3775.1 cm，并且在CeSc(BO)基质中发现Ce 4f态的F和F子态的超大多重分裂能量约为3000 cm。在CeSc(BO):Cr的激发光谱中观察到典型的电子热振动峰。在此基础上，估计了CeSc(BO)基质的最小声子能量，约为347.7 cm。最后，通过Ce发射和Cr再吸收的方式证明了导致CeSc(BO)中Cr的光致发光远高于其他基质的能量转移。
