Qu Ming-Yang, Li Ting-Qu, Liu Qiao-Li
Key Laboratory for Special Functional Materials in Jilin Provincial Universities, Jilin Institute of Chemical Technology, Jilin 132022, China.
School of Materials Science and Engineering, Key Laboratory of Mobile Materials, MOE, and State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China.
Materials (Basel). 2022 Sep 30;15(19):6817. doi: 10.3390/ma15196817.
The existence of so-called blue-green cavities in the luminescence spectrum has been a hindrance to the improvement in the performance of traditional phosphor-converted white light emitting diodes. The commercial phosphors synthesized in reducing atmospheres can also cause problems such as equipment complexity, increased cost, and environmental pollution. Herein, a series of cyan-emitting LuGaAlO: Ce (x = 0, 1, 2, 3, 4) garnet phosphors were synthesized by a traditional solid-state reaction in a nonreducing atmosphere at different temperatures. The crystal structure, grain morphology, optical properties, and thermal quenching behavior were used to analyze the optical properties of the as-prepared phosphors. The luminescence intensity of samples is affected by the synthesis temperature and energy gap between the conduction band and the lowest energy of the 5d excited state of the host lattice. With the substitution of Al by Ga, the regularity of the excitation and emission band movement is determined by the combined effects of crystal field splitting (CFS) and the nephelauxetic effect (NE). The temperature dependence of luminescence was studied. The thermal quenching mechanism was clarified by the thermal ionization model. Finally, by employing LuGaAlO: Ce as a cyan component, a w-LED with a high color rendering index of 93.2 and low correlation color temperature of 3880 K based on a blue chip and commercial red phosphors were fabricated in order to explore its possible application in high quality w-LED.
发光光谱中所谓的蓝绿色空洞的存在一直阻碍着传统磷光转换白光发光二极管性能的提升。在还原气氛中合成的商用磷光体还会引发诸如设备复杂、成本增加和环境污染等问题。在此，通过传统固态反应在不同温度的非还原气氛中合成了一系列发射青色光的LuGaAlO:Ce（x = 0、1、2、3、4）石榴石磷光体。利用晶体结构、晶粒形态、光学性质和热猝灭行为来分析所制备磷光体的光学性质。样品的发光强度受合成温度以及导带与主体晶格5d激发态最低能量之间的能隙影响。随着Ga取代Al，激发和发射带移动的规律由晶体场分裂（CFS）和光谱项收缩效应（NE）的综合作用决定。研究了发光的温度依赖性。通过热电离模型阐明了热猝灭机制。最后，为了探索其在高质量白光发光二极管中的可能应用，采用LuGaAlO:Ce作为青色组分，基于蓝色芯片和商用红色磷光体制备了显色指数高达93.2且相关色温低至3880 K的白光发光二极管。
