RUI: Investigation of Electron Migration and Trapping in Doped Luminescent Materials

技术描述：本课题研究固态发光材料在真空紫外激发下的电子-空穴（e-h）对输运和俘获过程。这些材料由氧化物主体和稀土掺杂剂组成。在真空紫外激发下，在寄主中产生e-h对，它必须迁移并被掺杂剂捕获才能发光。该研究项目解决了两个基本问题：(1)掺杂态相对于主能带态的位置如何影响e-h转移效率？(2)掺杂剂的选择对50 - 500纳米颗粒的表面损失程度有多大影响？这是通过对控制粒径的材料进行系统的光谱研究，并在当前模型的背景下对这些数据进行评估来完成的。这些实验数据的分析和建模允许评估e-h对在给定宿主中的迁移率，以及吸收的能量因体积缺陷和表面陷阱而损失的程度。这种差异对于开发具有高表面面积的高效纳米级光学材料尤为重要。该项目还将这些方法应用于更大的带隙磷酸盐宿主。非技术描述：本研究的目的是了解在真空紫外激发下控制固态发光材料效率的基本结构/性质关系，特别是具有亚微米粒度的材料。这种材料通常表现出不同于它们的大块材料的特性，并且可以提高某些技术的性能，例如高清显示器。PI在中央华盛顿大学（Central Washington University）建立了一个严格的固态化学研究项目，调查团队的大部分由本科生组成。学生们正在获得更深入、更广泛的科学训练，这为研究生学习或未来的职业努力做好了良好的准备。在PI实验室接受培训的本科生经常在同行评议的期刊上发表论文，并按惯例继续攻读研究生学位。

Technical Description: This research project involves the study of electron-hole (e-h) pair transport and trapping processes in solid-state luminescent materials under vacuum ultraviolet excitation. These materials are comprised of an oxide host and a rare-earth dopant. Under vacuum ultraviolet excitation, an e-h pair is created in the host that must migrate and be trapped by the dopant for luminescence to occur. The research project addresses two fundamental questions: (1) How is the efficiency of e-h transfer affected by the position of dopant states relative to host band states? (2) How much does the choice of dopant influence the degree of surface loss observed in particles with sizes of from 50 to 500 nanometers? This is accomplished through systematic spectroscopic investigations of materials of controlled particle size, and the evaluation of these data in the context of current models. The analysis and modeling of these experimental data allow for the assessment of the mobility of e-h pairs in a given host, as well as the degree to which absorbed energy is lost to bulk defects versus surface traps. Such a differentiation is especially important to the development of efficient nanoscale optical materials that have an intrinsically high surface area. The project also applies these methods to larger bandgap phosphate hosts.Non-technical Description: The objective of this research is to understand the fundamental structure/property relationships that govern the efficiency of solid-state luminescent materials, especially materials with sub-micrometer particle sizes, under vacuum ultraviolet excitation. Such materials often exhibit properties different from their bulk counterparts, and can improve the performance of certain technologies such as in high-definition displays. The PI has established a rigorous research program in solid-state chemistry at Central Washington University, with undergraduate students comprising the bulk of the investigative team. Students are gaining a deeper and broader scientific training, which serves as excellent preparation for graduate school or future professional endeavors. Undergraduate students trained in the PI's lab often published papers in peer-reviewed journals and routinely go on to pursue graduate degrees.