NaYF4:Yb,Er/NaYF4 Core/Shell Nanocrystals with High Upconversion Luminescence Quantum Yield
NaYF4:Yb,Er/NaYF4 Core/Shell Nanocrystals with High Upconversion Luminescence Quantum Yield
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DOI：
10.1002/anie.201803083
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发表时间：
2018-07-09
影响因子：
16.6
通讯作者：
Haase, Markus
中科院分区：
文献类型：
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作者：
Homann, Christian;Krukewitt, Lisa;Haase, Markus
基于无水稀土乙酸盐，通过改进的合成程序制备了平均尺寸在 15 至 45 nm 之间的上转换核/壳纳米晶体。所有颗粒均由 NaYF4:Yb,Er 核（掺杂 18% Yb3+ 和 2% Er3+）和 NaYF4 惰性壳组成，壳厚度等于核颗粒的半径。对一系列不同激发功率密度下的光致发光量子产率的绝对测量表明，45nm核/壳颗粒的量子产率已经非常接近微晶上转换荧光粉的量子产率。通过相同方法制备的较小核/壳颗粒仅表现出量子产率的适度下降。例如，15nm 核/壳颗粒的量子产率在高功率密度 (100Wcm(-2)) 下比块状上转换荧光粉减少了三倍，在低功率密度 (1Wcm(-2)) 下减少了大约十倍。
Upconversion core/shell nanocrystals with different mean sizes ranging from 15 to 45nm were prepared via a modified synthesis procedure based on anhydrous rare-earth acetates. All particles consist of a core of NaYF4:Yb,Er, doped with 18% Yb3+ and 2% Er3+, and an inert shell of NaYF4, with the shell thickness being equal to the radius of the core particle. Absolute measurements of the photoluminescence quantum yield at a series of different excitation power densities show that the quantum yield of 45nm core/shell particles is already very close to the quantum yield of microcrystalline upconversion phosphor powder. Smaller core/shell particles prepared by the same method show only a moderate decrease in quantum yield. The quantum yield of 15nm core/shell particles, for instance, is reduced by a factor of three compared to the bulk upconversion phosphor at high power densities (100Wcm(-2)) and by approximately a factor of 10 at low power densities (1Wcm(-2)).