Na^+掺杂对LiYF_4∶Er^(3+)/Yb^(3+)上转换发光性能的影响

Influence of Na^+ Doping on Upconversion Luminescence of LiYF_4:Er^(3+)/Yb^(3+) Microcrystals

上转换发光材料由于低的发光效率,限制了其在太阳电池中的实际应用。为解决此问题,采用溶剂热法制备了LiYF4∶Er3+/Yb3+上转换发光颗粒,在LiYF4基质中引入Na+来打破Er3+周围晶体场的对称性,增强其发光性能。研究了Na+掺杂对LiYF4∶Er3+/Yb3+的结构、形貌及其发光的影响。结果表明:掺杂的Na+可以裁剪Er3+周围的晶体场,当Na+摩尔分数为15%时,得到了较大的发光增强,绿光和红光发射分别获得4.2倍和2.9倍的增强。Er3+周围晶体场对称性的降低和材料中OH基团的减少是其发光增强的主要原因。

The applications of the upconversion( UC) phosphors in solar cells are still constrained because of their relatively low luminescence efficiency. In this work,LiYF4∶Er3+/Yb3+ co-doped with different concentrations of Na+was prepared by a simple and green hydrothermal procedure. The co-doping of Na+was proposed to enhance UC luminescence of LiYF4∶Er3+/Yb3+ microcrystals. The influence of Na+on the crystal structure,morphology and luminescence of LiYF4∶Er3+/Yb3+ was investigated. The results indicate that the co-doping of Na+can tailor the local crystal field around Er3 +. Compared with LiYF4∶Er3+/Yb3+,the green and red emission intensities ofLiYF4∶Er3+/Yb3+ co-doped with 15% Na+are enhanced by about 4. 2 and 2. 9 times,respectively. The distortion of the local symmetry and the reduction of OH groups are confirmed to be the origin of the improvement.