科研之友
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摘要
The phenomenon of luminescence concentration quenching exists widely in lanthanide-based luminescent materials, setting a limit on the content of lanthanide emitter that can be used to hold the brightness. Here, we introduce a concept involving energy harvesting by a strong absorber and subsequent energy transfer to a lanthanide that largely alleviates concentration quenching. We apply this concept to Nd3+ emitters, and we show both experimentally and theoretically that the optimal doping concentration of Nd3+ in colloidal NaYF4:Nd upconverting nanoparticles is increased from 2 to 20 mol% when an energy harvestor organic dye (indocyanine green, ICG) is anchored onto the nanoparticle surface, resulting in similar to 10 times upconversion brightness. Theoretical analysis indicated that a combination of efficient photon harvesting due to the large absorption cross section of ICG (similar to 30 000 times higher than that of Nd3+), non-radiative energy transfer (efficiency similar to 57%) from ICG to the surface bound Nd3+ ions, and energy migration among the Nd3+ ions was able to activate Nd3+ ions inside the nanoparticle at a rate comparable with that of the pronounced short-range quenching interaction at elevated Nd3+ concentrations. This resulted in the optimal concentration increase to produce significantly enhanced brightness. Theoretical modeling shows a good agreement with the experimental observation. This strategy can be utilized for a wide range of other lanthanide-doped nanomaterials being utilized for bioimaging and solar cell applications.
- 出版日期2016-11-23
- 单位哈尔滨工业大学
