稀土离子掺杂的自激活下转换发光材料研究

In order to improve the performance of absorption cabability and absorption region and the eficiency of downconversion, the study for downconverson of self-activated materials doped with rare earths are proposed here. The materials choose self-activated materials as matrices which exhibit high efficiency of energy transfer, and broad-band absorption capability in ultraviolet and visible regions. The doping ions of rare earths also have a wide band absorption capacity in ultraviolet and visible regions. The self-activated materials doped with rare earths can greatly improve the efficiency of energy utilization in UV-visible region of the solar spectrum and conversion efficiency. This project targets different self-activated materials doped with different rare earths, and focuses the influence of different matrix components on absorption behaviors of the self-activated matrix itself and the doping ions in UV-visible region, efficiency of energy transfer and luminescent intensity of Yb ions. The mechanisms of energy transfer are revealed through study on the changes of luminescent properties after and before doping rare earths ions. And the influencing factors of conversion efficiency and luminescent intensity are clarified. The methods of increasing the quenching concentration of Yb ions or preventing concentration quenching are explored. New ideas and new material system for rare-earth near-infrared downconversion materials are to be provided through the study.

为提高太阳光谱中紫外可见区域的能量吸收能力和吸收范围以及下转换效率，项目申请人提出了"稀土离子掺杂的自激活材料下转换发光材料研究"的课题。它选择能量传递效率高且在紫外可见区域具有宽谱带吸收能力的自激活材料为发光主体，并掺杂在该区域同样具有宽谱带吸收能力的稀土离子，通过与发光中心Yb离子的能量传递过程，达到近红外下转换的效果，可极大地提高太阳光谱中紫外可见区域的能量利用效率和下转换效率。本课题针对不同的自激活材料体系，掺杂不同的稀土离子，通过比较不同基质组分对自激活基质本身和掺杂的稀土离子在紫外可见波段的吸收行为、能量传递效率和Yb离子发光强度的影响；通过比较稀土离子掺杂前后的下转换光谱性质变化，揭示稀土离子掺杂的自激活下转换材料的能量传递机理，阐明影响下转换效率和Yb离子发光强度的因素。探索提高Yb离子猝灭浓度或防止浓度猝灭的方法。为稀土近红外下转换材料研究提供新思路和新材料体系。

基于宽谱带跃迁的稀土近红外下转换材料是一种新型光学功能材料，在提高太阳能电池转换效率应用方面表现出优异性能。本项目针对该应用成功在紫外可见区域具有宽谱带吸收能力的Na2YMg2(VO4)3和Sr2CaWO6两类自激活基质，通过与发光Yb离子的能量传递，实现了近红外下转换。通过自激活基质本身在紫外可见波段的吸收行为、能量传递效率和Yb离子发光强度的影响，揭示了这两类自激活下转换材料的能量传递机理为共合作能量传递实现。研究显示，这两类基质分别在250-400nm和200-300nm具有宽谱带吸收能力，其量子效率分别达到了160%和190%。