State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.
Nanoscale. 2013 Sep 7;5(17):8084-9. doi: 10.1039/c3nr01916k.
The application of upconversion nanoparticles (UCNPs), especially in vivo, has so far been hampered by their relatively low upconversion efficiency. In this work, a strategy of Li(+) doping was revisited with the aim of enhancing UV to blue UC luminescence of NaYF4:Yb(3+), Tm(3+) nanocrystals. We have demonstrated that the short wavelength UC emission bands were indeed significantly enhanced. Compared to lithium-free NaYF4:Yb(3+), Tm(3+), the UC emission intensities of 452 nm and 479 nm of the NPs co-doped with 7 mol% Li(+) ions were increased by 8 and 5 times, respectively. The mechanism of the enhancement was discussed and the improvement of the nanoparticles' crystallinity and the distortion of the local symmetry around the Tm(3+) ions, when the Li(+) ions were introduced, were confirmed to be the origin of the improvement.
上转换纳米粒子（UCNPs）的应用，特别是在体内，迄今为止一直受到其相对较低的上转换效率的阻碍。在这项工作中，重新研究了 Li(+)掺杂策略，目的是增强 NaYF4:Yb(3+)，Tm(3+)纳米晶体的紫外到蓝光上转换 UC 发光。我们已经证明，短波长 UC 发射带确实得到了显著增强。与不含锂的 NaYF4:Yb(3+)相比，共掺杂 7mol%Li(+)离子的 NPs 的 452nm 和 479nm 的 UC 发射强度分别增加了 8 倍和 5 倍。讨论了增强的机制，并证实了 Li(+)离子的引入提高了纳米颗粒的结晶度和 Tm(3+)离子周围局部对称性的变形，这是改善的原因。
