氮化物发光材料的溶胶-凝胶法制备及其发光影响机理研究

White light emitting diodes (LEDs) will become the main illumination pattern in the future because of their prominent advantages such as energy conservation and environmental protection. As a key component of white LEDs light source, phosphors play an important role in the optical properties of white LEDs. Nitride based phosphors with excellent luminescence properties have become the research focus in phosphors field. But there are some disadvantages in all synthesis methods of nitride based phosphors until now, which restrict the application of nitride based phosphors in white LEDs seriously. On the basis of outstanding advantages of nitrides structure, M2-xLnxSi5-yAlyN8:Eu2+, Re3+ (M=Ca, Sr, Ba；Re=Ce, Dy, Tb；Ln=Y, La, Gd；x, y≤0.5) phosphors are designed and prepared by a novel sol-gel assisted method. Based on the structure calculation of series of nitride, the effects of preparation process on luminescence properties of phosphors were investigated. Finally, a strong white light emission is achieved by the encapsulation of M2-xLnxSi5-yAlyN8:Eu2+, Re3+ phosphors on LED chip. The thermodynamic conditions of nitride synthesized through sol-gel-ammonia nitridation method are ascertained, and the synthesis mechanism of nitrides is revealed. Effects of Ln3+, Al3+ introducing on the structure and energy transfers in the nitride crystal are studied intensively for exploring the related mechanism, and the influence of Eu2+, Re3+ co-doping on the white light is ensured as well. The applications of nitride based phosphors and corresponding white LEDs are increased in market on the aspect of technique, and the novel, high-end nitride based phosphors for white LEDs with proprietary technology are tried to be realized in China at last.

白光LED因其显著的节能环保优势而将成为未来的主体照明。作为白光LED光源的核心组成，荧光粉在光学性能上起着重要作用，其中具有优异发光的氮化物荧光粉成为当前的研究焦点。但目前氮化物的制备方法都存在问题，制约了其在白光LED上的应用。项目设计并利用溶胶-凝胶法辅助合成M2-xLnxSi5-yAlyN8:Eu2+, Re3+ (M=Ca, Sr, Ba；Re=Ce, Dy, Tb；Ln=Y, La, Gd；x, y≤0.5)发光材料。在该体系结构计算基础上，研究制备过程中发光影响因素，最后在LED芯片上实现白光发射。探明溶胶-凝胶-氨氮化法合成氮化物的热力学条件，并揭示其氮化机理。研究Ln3+、Al3+的掺杂对氮化物晶体结构与内部能量传递的影响机理，同时确定Eu2+, Re3+双掺杂对白光的影响。从技术上提升氮化物及其白光LED的应用，争取实现我国新型、高端白光LED用氮化物的自主核心技术。

本项目利用Y3+-Al3+离子对共取代制备了Sr2-xYxSi5-xAlxN8:Eu2+系列荧光材料，并考察了溶胶-凝胶法、Ce3+、Eu2+-Ce3+、Eu2+-Dy3+掺杂、葡萄糖为碳源等对发光性能的影响。所制备的荧光材料具有Sr2Si5N8晶体结构，并显现出稀土离子各自的特征发光。项目通过Y3+-Al3+离子对共取代提升了Sr2Si5N8:Eu2+的发光效果，并探讨了结构取代增强发光机理。增强后的氮化物荧光材料可进一步满足白光LED光学需求，有利于提升其在照明领域的应用。