基于Eu2+配位环境调控对固溶体白光荧光粉的设计制备、光谱调控及机理研究

Phosphor-converted white light-emitting diodes (WLEDs) will dominate the next solid-state lighting. Concerning the low luminous efficiency of white-lighting induced by re-absorption energy loss in tricolor-phosphors-converted WLEDs, this project intends to design the crystal-site of luminescence centers, so as to produce coordinate environments acting on luminescence centers that, can provide a binary complementary colors. And then, a single-phased white-lighting phosphors is expected to obtained by mixing the coordinate environments. By this way, we expect to solve the low efficiency of white-lighting induced by the mixing processes of tricolors. In this project, we choose Sr3N(PO4)3:Eu2+（N=Ce, Bi, Lu) compounds with highly flexible of host lattice as host materials. By substituting Sr site with Mg/Ca/Ba and N site with La/Y/Gd to adjust the composition of host, so as to induce new Eu2+ centers with blue/green/orange-yellow emission in yellow-/violet-/blue-green-emitting phosphors. By this way, a white-lighting phosphor with a tunable color and adjustable chemical/physical properties is expected to obtain. Influence of doping on the crystal structure, luminescence properties and the coordinate environment of Eu2+ will be investigated. It is expected to open a new design route and give an experimental foundation to obtain high-performance white-lighting phosphors.

荧光粉转换的高性能白光LED将主导下一代固态照明。针对三基色荧光粉混合转换白光中自吸收能量损耗引起的白光发光效率低问题，本项目从发光中心的晶体学格位设计出发，构建能发射二元互补色的发光中心配位环境，通过杂化其配位环境，获得一种非混合型白光发射材料，克服由荧光粉混合引起的白光光效低问题。选择高度晶格灵活性的Sr3N(PO4)3:Eu2+（N=Ce, Bi, Lu)黄/紫/蓝绿色发光材料为基质。通过Sr位（Mg/Ca/Ba）和N位（La/Y/Gd）取代，调整基质化学组分，在黄/紫/蓝绿色材料中诱导出发射互补色的（蓝/绿/橙黄色）新的Eu2+中心，结合上述Eu2+发光获得发光颜色和性能可调的白光材料。研究组分变化对晶体结构、发光特性和Eu2+格位配位环境的影响规律，优化发光效率和光谱分布，获得高性能的白光发光材料。本项目将为高性能白光荧光粉的设计研发提供新的设计思路与奠定实验基础。

三基色荧光粉混合转换白光是实现紫外光激发白光LED的重要方案之一。为克服三基色荧光粉混合转换白光中再吸收和非一致光/热衰竭问题，直接发射白光的非混合荧光材料是一种非常有潜力研究方案。但单一组分白光荧光粉还存在量子效率低，热稳定性差，激活剂在多阳离子基质中格位选择性占据机理不清楚的问题。揭示激活剂在基质晶格中格位选择性占据的物理机制，掌握白光荧光材料的设计准则，有望能够解决上述关键科学问题。本项目以二元互补色发光材料（二元互补色：蓝色和黄色、绿色和紫色、橙黄色与蓝绿色）为研究对象，选择高度晶格灵活性的Sr3N(PO4)3:Eu2+（N=Ce, Bi, Lu)黄/紫/蓝绿色发光材料为基质，通过调控基质组分，杂化Eu2+配位环境，优化发光效率和光谱分布，构建一种非混合型白光发射材料，获得高性能的白光LED器件。探索基质组分、晶相，形貌，配位环境，共价性和格位的对称性对Eu2+发光的影响，揭示Eu2+局部微结构变化对荧光粉宏观发光性质的影响。研究温度、湿度和气氛对样品发光热温度性和化学稳定性的影响。通过合成工艺优化，最终获得具有自主知识产权的，可产业化的非混合型白光荧光粉及其白光LED器件。