Energy-Cascaded Upconversion in an Organic Dye-Sensitized Core/Shell Fluoride Nanocrystal.
Energy-Cascaded Upconversion in an Organic Dye-Sensitized Core/Shell Fluoride Nanocrystal.
复制标题
DOI：
10.1021/acs.nanolett.5b02830
复制
发表时间：
2015-11-11
期刊：
影响因子：
10.8
通讯作者：
Prasad PN
中科院分区：
文献类型：
--
作者：
Chen G;Damasco J;Qiu H;Shao W;Ohulchanskyy TY;Valiev RR;Wu X;Han G;Wang Y;Yang C;Ågren H;Prasad PN
掺杂镧系元素的上转换纳米颗粒有望用于生物成像、太阳能电池和立体显示器。然而，它们的发射亮度和激发波长范围受到镧系离子的微弱和窄带吸收的限制。在这里，我们介绍了一个多步骤级联能量转移的概念，从广泛的红外捕获有机染料敏化离子在壳的外延设计的核/壳无机纳米结构，与顺序的非辐射能量转移到上转换离子对的核心。我们表明，这一概念，当实施在一个核壳结构与抑制表面相关的发光淬灭，产生多光子（三光子、四光子和五光子）上转换量子效率高达19%（上转换能量转换效率9.3%，上转换量子产率4.8%），这比通常报道的镧系元素基纳米结构中在800 nm处的上转换效率高约100倍，沿着具有宽的红外激发光谱范围（超过150 nm）和每个单个纳米颗粒1.47 × 10−14 cm 2的大吸收截面。这些功能使前所未有的三光子上转换（肉眼可见的蓝光）的非相干红外光激发的功率密度相当于太阳辐射在地球表面，具有广泛的应用这些有机-无机核/壳纳米结构与能量级联上转换的影响。
Lanthanide-doped upconversion nanoparticles hold promises for bioimaging, solar cells, and volumetric displays. However, their emission brightness and excitation wavelength range are limited by the weak and narrowband absorption of lanthanide ions. Here, we introduce a concept of multistep cascade energy transfer, from broadly infrared-harvesting organic dyes to sensitizer ions in the shell of an epitaxially designed core/shell inorganic nanostructure, with a sequential nonradiative energy transfer to upconverting ion pairs in the core. We show that this concept, when implemented in a core–shell architecture with suppressed surface-related luminescence quenching, yields multiphoton (three-, four-, and five-photon) upconversion quantum efficiency as high as 19% (upconversion energy conversion efficiency of 9.3%, upconversion quantum yield of 4.8%), which is about ~100 times higher than typically reported efficiency of upconversion at 800 nm in lanthanide-based nanostructures, along with a broad spectral range (over 150 nm) of infrared excitation and a large absorption cross-section of 1.47 × 10−14 cm2 per single nanoparticle. These features enable unprecedented three-photon upconversion (visible by naked eye as blue light) of an incoherent infrared light excitation with a power density comparable to that of solar irradiation at the Earth surface, having implications for broad applications of these organic–inorganic core/shell nanostructures with energy-cascaded upconversion.