一种大功率白光LED用新型层状复相荧光陶瓷的研究

High-power white light emitting diodes (white-LEDs) are accepted as a superior white-light source due to their high efficiency, energy-saving, and environmental compatibility. However, there are some problems to be solved, such as thermal degradation, deficiency of the red component in the emission spectrum, high-cost, and etc. The present project aims to develop novel phosphor ceramic materials to solve the above problems. Taking advantage of the high thermal conductivity, high thermal stability, and low-cost of the SrF2 ceramic, we propose to develop SrF2-YAG:Ce and SrF2-CaAlSiN3:Eu composite phosphor ceramics, where the phosphors are embedded in non-luminescent SrF2 matrix. The relationship between the microstructure and luminescent properties of the phosphor ceramics will be studied in detail. The research also investigates the distribution of the two phases in the composite phosphor ceramic. Based on the above studies, a novel layered SrF2-YAG:Ce/SrF2-CaAlSiN3:Eu composite phosphor ceramic will be prepared to improve the color rendition and the correlated color temperature of the lighting source. In addition, we propose to rough the surface of the ceramic phosphor by the wet-etching method, so that more light can be emitted in the forward direction. The light extraction efficiency and heat removal of the white LED can be enhanced.

功率型白光LED由于具有效率高、能耗低、无污染等优点，受到广泛关注。本项目针对其在发展过程中遇到的光衰、红光成分不足、成本高等问题，创新提出：1）利用SrF2热导率高（~ 8.3 Wm-1K-1）、稳定性好、制备温度低（~ 700 oC）等优点，在实现原料粉体两相均匀分布、探明构效关系的基础上，低成本研制光学质量高、发光性能优异的黄色SrF2-YAG:Ce、红色SrF2-CaAlSiN3:Eu复相荧光陶瓷；2）基于SrF2-YAG:Ce、SrF2-CaAlSiN3:Eu陶瓷的制备技术, 获得SrF2-YAG:Ce/SrF2-CaAlSiN3:Eu层状复相荧光陶瓷，通过调控合成光谱，解决白光LED红光成分不足的问题，从而有效改善光源的色温和显色指数。另外，通过粗化陶瓷表面，提高荧光陶瓷光提取效率，改善散热，最终实现高效的白光输出。发展具有实用价值和自主知识产权的高性能荧光陶瓷材料。

高性能荧光陶瓷材料在白光LED领域受到了广泛的关注。本项目致力于研制高性能CaF2-YAG:Ce复相荧光陶瓷。通过工艺优化，在700 ℃的条件下，成功的制备了CaF2-YAG:Ce荧光陶瓷，该荧光陶瓷具有较好的热稳定性（150℃时，其荧光强度仅下降9%）；基于该荧光陶瓷，获得了高显色指数（70.1-82.7）、色温可调（4021-7941 K）的白光。此外，CaF2-YAG:Ce复相荧光陶瓷的发光性能主要取决于YAG:Ce粉体，因此开展提高YAG:Ce粉体发光性能的研究具有重要意义。本研究中创新性的提出了以B4C为添加剂对YAG:Ce进行改性，与未添加B4C相比，制备的YAG:Ce的发光强度提高160%，并且具有高的热稳定性，200℃时，其荧光强度仅损失8%，优于商用YAG:Ce粉体。发表SCI论文6篇，申请发明专利5项，