State Key Laboratory of ASIC and System, SIST, Fudan University, Shanghai, 200433, China.
Materials Research Institute and School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
Sci Rep. 2017 Jul 11;7(1):5066. doi: 10.1038/s41598-017-05350-9.
Infra-red emission (980 nm) of sub 10 nm Yb-doped NaYF nanoparticles has been sensitized through the excitation of 2-hydroxyperfluoroanthraquinone chromophore (1,2,3,4,5,6,7-heptafluro-8-hydroxyanthracene-9,10-dione) functionalizing the nanoparticle surface. The sensitization is achieved with a broad range of visible light excitation (400-600 nm). The overall near infra-red (NIR) emission intensity of Yb ions is increased by a factor 300 as a result of the broad and strong absorption of the chromophore compared with ytterbium's intrinsic absorption. Besides the Yb NIR emission, the hybrid composite shows organic chromophore-based visible emission in the orange-red region of the spectrum. We observe the energy migration process from the sensitized Yb ions at the surface to those in the core of the particle using time-resolved optical spectroscopy. This highlights that the local environments for emitting Yb ions at the surface and center of the nanoparticle are not identical, which causes important differences in the NIR emission dynamics. Based on the understanding of these processes, we suggest a simple strategy to control and modulate the decay time of the functionalized Yb-doped nanoparticles over a relatively large range by changing physical or chemical parameters in this model system.
亚纳米 Yb 掺杂 NaYF 纳米粒子的红外发射（980nm）通过激发功能化纳米粒子表面的 2-羟基全氟蒽醌发色团（1,2,3,4,5,6,7-七氟-8-羟基蒽-9,10-二酮）来敏化。敏化是通过可见光激发（400-600nm）来实现的。与镱的本征吸收相比，发色团的宽且强吸收使 Yb 离子的整体近红外（NIR）发射强度增加了 300 倍。除了 Yb 的 NIR 发射外，杂化复合材料在光谱的橙红色区域显示出基于有机发色团的可见发射。我们使用时间分辨光光谱法观察从表面敏化的 Yb 离子到颗粒中心的能量迁移过程。这表明表面和颗粒中心发射 Yb 离子的局部环境并不相同，这导致 NIR 发射动力学的重要差异。基于对这些过程的理解，我们提出了一种简单的策略，通过改变该模型系统中的物理或化学参数，在相对较大的范围内控制和调节功能化 Yb 掺杂纳米粒子的衰减时间。
