Controlling the optical scattering of plasmonic nanoparticles using a thin dielectric layer
Controlling the optical scattering of plasmonic nanoparticles using a thin dielectric layer
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DOI：
10.1063/1.4804964
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发表时间：
2013-05-14
影响因子：
3.2
通讯作者：
Smith, J. M.
中科院分区：
文献类型：
--
作者：
Powell, A. W.;Wincott, M. B.;Smith, J. M.
研究了薄介质膜对高折射率衬底上金属纳米颗粒(MNPs)等离子体行为的影响。利用有限差分的时间域模拟方法，研究了银纳米粒子的光学性质随薄膜厚度、折射率和粒子在薄膜中的位置的变化。我们证明，在高折射率衬底的空气界面上围绕MNP添加一层薄膜，其中n(空气)和lt；n(薄膜)和lt；n(衬底)总是会增加耦合到衬底上的光的比例(F-subs)。研究发现，在不符合n(空气)和n(薄膜)和n(衬底)的层中放置会导致F-subs的增强降低。这项工作的主要应用是在薄膜太阳能电池中捕捉光。我们发现，对于太阳的不同波长，薄膜的包裹体可以使耦合到衬底中的辐射增加30%。薄膜结构的其他潜在好处，例如更大的散射共振的可调性，增加了基片中的光的路径长度，以及对发射图案的某种控制。研究发现，与简单界面上的粒子相比，薄膜中的mNPs产生了更精细的结构发射图案，这表明这项研究有可能应用于光学纳米天线。(C)2013 AIP出版有限责任公司。
The effect of a thin dielectric film on the plasmonic behaviour of metal nanoparticles (MNPs) above a high refractive index substrate is explored. Using finite-difference time domain simulations, the optical properties of Ag nanoparticles are investigated as a function of film thickness, refractive index, and particle position within the film. We demonstrate that the addition of a film around a MNP at the air interface of a high-index substrate, where n(air) < n(film) < n(substrate), will always increase the fraction of light coupled to the substrate (F-subs). It is found that placement within a layer that does not conform to n(air) < n(film) < n(substrate) can lead to reduced enhancements in F-subs. The principal application for this work is for light-trapping in thin-film solar cells. We show that the inclusion of a thin film can increase the fraction of radiation coupled into the substrate by up to 30% for solar wavelengths. Additional potential benefits of the film structure, such as greater tunability of scattering resonances, an increase in path length of light in the substrate, and some control over the emission pattern are demonstrated. MNPs in a film are found to produce a more finely structured emission pattern than particles at a simple interface, showing potential for this research to be applied to optical nanoantennae. (C) 2013 AIP Publishing LLC.