稀土上转换发光材料多级空心结构的有效构筑与发光性能增强的协同效应研究

With the special morphology structure as starting point, many kinds of materials will be designed for the sake of enhancing the upconversion luminescence properties. It is important to develop the yttrium oxides based luminescent materials with multi-shell hollow structure, composite structure and sandwich structure by the facile and environmental approach. The upconversion luminescence performance can be improved by the synergistic effect derived from the multiple reflections of the NIR excitation light in the multi-shell hollow structures, the reduced surface quenching site by the composite structure and the surface plasmon resonance. It also has the vital significance to summarize the synthetic law of the multi-shell hollow structure, composite structure and sandwich structure. During the preparation process, various factors that may affect the upconversion luminescence performance will be controlled, including the thickness of the shell layer, the spacing of the layers, the size of the hollow-shell structure, the loading capacity of Au/Ag nanoparticles and the size of Au/Ag nanoparticles. It has important significance for the exploration of the relationship between the morphology, compositions and the luminescence properties as well as the energy transfer mechanism, which will provide foundation for the application of upconversion luminescent materials with hollow-shell structure.

本项目以增强稀土上转换发光材料的发光性能为目的，从特殊形貌结构出发，进行材料设计。利用简单、环保的方法制备具有多级空心结构、复合结构及三明治型多级空心结构的钇氧化物稀土上转换发光材料。通过近红外激发光在空心结构内部的多级反射、复合结构减少表面猝灭位点以及表面等离子体共振的协同效应，提高上转换发光性能。总结多级空心结构、复合结构与三明治型多级空心结构的合成规律。在制备过程中，对可能影响上转换发光性能的各种因素（例如壳层的厚度、层间距、空心结构的尺寸、Au/Ag纳米粒子的负载量、Au/Ag纳米粒子的大小等）进行调控。探讨形貌、组成与发光性能的构效关系。探究能量在多级空心结构中的传递机制，为实现具有空心结构的稀土上转换发光材料的应用奠定基础。

稀土上转换发光材料因其独特的发光性能以及广泛的应用备受研究者的关注。本项目针对空心结构的稀土上转换发光材料的构筑机理以及空心结构对上转换发光性能的作用机理进行了研究。我们采用模板法或者改进的硬模板法构筑了成分与壳层数可控的稀土上转换发光材料。CeO2具有无毒、生物兼容性好等优势，我们合成了尺寸超小的壳层数可控的稀土离子掺杂的CeO2多级空心结构，对其亲水性进行了修饰。通过缓释策略，对复杂氧化物Y2Mo4O15:Yb3+/Er3+多级空心结构的可控制备进行了探讨。实现了模板法构筑YVO4:Yb3+/Er3+@TiO2异质空心结构等。系统的研究了空心结构的合成机理及形貌与发光性能的依存关系。探究了能量在多级空心结构中的传递与迁移机制，阐明了多级空心结构对稀土上转换发光性能的增强机制。该研究结果为提高稀土上转换发光材料的效率提供了依据。除此之外，我们还研究了尺寸可调剂的β-NaYF4:Yb/Er纳米颗粒与绿光发射增强的关系。