Department of Chemistry and The State Key Laboratory of Molecular Engineering of Polymers and Institute of Biomedicine Science and Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University, Shanghai, 200433, P. R. China.
Nanoscale. 2017 Feb 2;9(5):1964-1971. doi: 10.1039/c6nr07687d.
The development of rare-earth doped upconversion nanoparticles (RE-UCNPs) in various applications is fuelling the demand for nanoparticles with highly enhanced upconversion luminescence (UCL). Although the core/shell structure is proved to enhance the UCL effectively, there is still plenty of room to further improve the UCL by optimizing the doping ratio of the materials. In this article, a general strategy is demonstrated to achieve highly-enhanced visible UCL in core/shell nanostructured NaREF by increasing the doping ratio of Yb in the core region. The energy transfer from RE-UCNPs to surface quenching sites through Yb-Yb energy migration is demonstrated to be the main reason for restricting the doping ratio of Yb. Notable UCL enhancement (ca. 15 times) of core/shell structured α-NaYF:Yb,Er@CaF nanoparticles is observed by increasing the concentration of Yb to 98 mol%. The highly-enhanced visible UCL signal is used to guide the lymphatic vessel resection with the naked eye.
稀土掺杂上转换纳米粒子（RE-UCNPs）在各种应用中的发展推动了对具有高上转换发光（UCL）的纳米粒子的需求。尽管核/壳结构已被证明可以有效地增强 UCL，但通过优化材料的掺杂比，仍有很大的空间进一步提高 UCL。本文展示了一种通用策略，通过增加核区 Yb 的掺杂比，在核/壳纳米结构 NaREF 中实现了高度增强的可见 UCL。从 RE-UCNPs 到表面猝灭位点的能量转移通过 Yb-Yb 能量迁移被证明是限制 Yb 掺杂比的主要原因。通过将 Yb 的浓度增加到 98mol％，观察到核/壳结构的α-NaYF：Yb，Er@CaF 纳米粒子的 UCL 显著增强（约 15 倍）。高度增强的可见 UCL 信号可用于引导用肉眼切除淋巴管。
