纳米复合结构的稀土掺杂透明玻璃陶瓷中表面等离子体共振增强的量子剪裁发光

Rare-earth ions (REI) doped materials with near-infrared (NIR) quantum cutting (QC) luminescent characteristics are regarded as promising candidates to reduce the carrier thermalization loss in the solar cell, and thus improve the photo-electric conversion efficiency, however, the low optical absorption and the weak QC luminescence of REI limit their practical applications. In view of the fact that the effective optical absorption and fluorescent emission of REI could be dramatically enchanced by the surface plasmon resonance (SPR) effect of noble metal nanoparticles, this project aims to prepare novel transparent glass ceramics embedded with noble metal and REI doped fluoride nanocrystals by melt-quenching and heat-treating techniques, to investigate the plasmonic enhancement on the ultraviolet-blue light absorption and the NIR QC luminescence of REI. The main goal is to explore the SPR characteristics of noble metal nanoparticles among the oxyfluoride glass ceramics by utilizing the classical MIE light scaterring theory and Drude free electron theory; to mainly investigate the dynamical processes and related mechanisms for the plasmonic enhancement on NIR QC luminescence by the rate equation analysis; to summarize the effects of the size and distribution of noble metal/fluoride nanocrystals on the NIR QC emission features of REI; and furthermore to optimize the crystllization structures of the nano-composites for improving lighting performances.

具有近红外量子剪裁下转换发光特性的稀土掺杂材料在降低硅太阳电池的热化损失、提高光电转换效率方面有很大潜力，但是该材料的实际应用却受限于稀土的光吸收和下转换发射较弱等问题。鉴于贵金属纳米粒子的表面等离子体共振效应可以显著增强稀土离子的有效吸收和荧光发射，本项目拟采用熔体急冷法和后续热处理，制备同时含贵金属和稀土掺杂氟化物纳米晶的新型透明玻璃陶瓷，研究利用贵金属纳米粒子的表面等离激元增强稀土的紫外-蓝光吸收和近红外量子剪裁发光；结合经典的Mie光散射理论和Drude自由电子理论,探讨贵金属纳米粒子在氟氧化物玻璃陶瓷环境中的表面等离子体共振吸收特性；通过建立速率方程，重点研究材料中贵金属纳米晶表面等离激元荧光增强的动力学过程和机理，并总结贵金属和氟化物颗粒的尺度、分布对稀土近红外量子剪裁下转换发光性能影响的规律，进而优化纳米复合材料的晶化结构，进一步改善发光性能。

针对近红外量子剪裁下转换发光材料光吸收和下转换发射较弱的问题开展研究。采用熔体急冷法，成功制备了含Ag和氟化物纳米晶的新型透明玻璃陶瓷复合材料；通过优化玻璃组分和热处理工艺，使掺杂稀土（如Eu3+、Er3+和Yb3+等）以置换固溶方式进入氟化物纳米晶相环境中；通过调控Ag纳米晶的尺度，使其表面等离子体共振峰位与稀土（Tb3+，Tm3+，Pr3+）近红外量子剪裁发光的激发波长相匹配；利用Ag团簇向稀土能量传递，使Tb/Yb近红外量子剪裁下转换发射增强了~1.5倍（能量传递通道：Ag clusters→Tb3+→Yb3+）；分析了稀土在氟氧化物玻璃陶瓷中近红外发光的动力学过程；通过对复合材料组分-显微结构-光谱性能关系的综合评价，进一步改进了材料的制备工艺，优化了发光性能。此外，扩展了研究体系，制备了一系列含氟化物（YF3、 GdF3）、氧化物(Ga2O3、ZnAl2O4)、氯化物(Cs3LaCl6)纳米晶或Ce3+:YAG、Ce3+:Mg3Y2Ge3O12、 Ce3+:Gd3Al2Ga3O12, Mn4+:CaMg2Al16O27微米晶的玻璃陶瓷复合材料，这些材料展现出优异的可见上转换、超宽带近红外发光、下转移白光等发光特性，有望应用于光显示、光纤放大器和白光LED等领域。