镧系元素
化学
发光
猝灭(荧光)
光子上转换
纳米颗粒
光化学
吸收(声学)
离子
纳米材料
兴奋剂
分析化学(期刊)
纳米技术
光电子学
材料科学
荧光
光学
有机化学
复合材料
物理
作者
Wei Wei,Guanying Chen,Alexander Baev,Guang S. He,Wei Shao,Jossana A. Damasco,Paras N. Prasad
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 ∼10 times upconversion brightness. Theoretical analysis indicated that a combination of efficient photon harvesting due to the large absorption cross section of ICG (∼30 000 times higher than that of Nd3+), non-radiative energy transfer (efficiency ∼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.
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