表面等离子体聚焦调制及增强太阳能电池吸收研究

【作者】 柯智慧；

【导师】 周秀丽；

【作者基本信息】 电子科技大学 ， 光学， 2011， 硕士

【摘要】 金属表面等离子体(surface plasmon),是目前纳米光子学中最引人注目的应用研究方向;借助于金属界面,或者金属纳米结构,它可以将电磁场高度局限在纳米尺度的范围之内,使得光近场区域场强得到大幅度的提高;表面等离子体激元(SPPs)和局域表面等离子体(LSP)分别是其中的两个组成部分。理论上,利用SPPs的传播特性,可以开发出亚波长尺寸的光子器件;而利用LSP的场局限作用,可以将发散的电磁能量高度汇聚在金属纳米结构的近场区域。基于这两方面的特性,本论文分别进行了两种应用研究:1.为了研究远场超聚焦的可能,本论文研究了基于纳米孔结构的银薄膜等离子体透镜聚焦模型;调查了银薄膜的厚度对这种透镜聚焦效果的调制作用。利用时域有限差分法(FDTD),论文中分别计算和分析了一系列厚度的银薄膜透镜的光聚焦特性。仿真结果表明:一方面,由于SPPs的作用,该平板结构能够实现光聚焦,而且聚焦强度很高;另一方面,不同的银薄膜厚度,会得到不同的聚焦效果;增加银薄膜的厚度,会使得该透镜的焦距从近场,逐渐推移到远场;近场焦斑尺寸可以达到波长以下,而远场焦斑的大小略大于一个波长。2.为了提高有机物薄膜太阳能电池的光电转化效率,论文中考察了一种内嵌有金属纳米粒子的复合型有机物太阳能电池材料。借助三维的电磁波仿真软件,文中建立了金属-有机物混合薄膜结构;并且通过仿真计算,对比分析了金属粒子阵列对太阳能电池的光子吸收效率的影响。数据表明,由于LSP的共振效应,金属纳米粒子可以起到光子吸收的增强作用;在材料中,改变金属纳米粒子的位置,大小,形状,阵列周期,会得到不一样的场分布,增强光子吸收的效果也有较大的差别。最后,通过一系列的对比分析,论文总结出了金属纳米粒子阵列的最优布局,为设计混合型有机物薄膜太阳能电池提供了很好的依据。更多还原

【Abstract】 Metal surface plasmon forms the major part of the fascinating field of nanophotonics, at metallic interfaces or in metallic nanostructures, which has the ability to confine electromagnetic fields under dimensions on the order of or smaller than the wavelength, leading to an enhanced optical near field. Surface plasmon polaritons (SPPs) and localized surface plasmon (LSP) are two dividual ingredients belong to plasmon. Theoretically, to utilize the long propagation characteristic of SPPs, it is possible to develop many sub-wavelength dimension photonic devices; and make use of the LSP to exploit metal nanostructures to block radiation for sub-wavelength area electromagnetic energy’s confinement. Base on this two special properties, this thesis carry out two kind of application research:1. First of all, to investigate the possibility of far-field superfocusing, this thesis analyzes a plasmonic lens model, which is a metal film structure constituted with nano-pinholes; and then have make a study of the focus modulation property of this kind of plasmonic Lens. Finite-difference and time-domain (FDTD) method is used to analyze the focal properties. Numerical analysis results demonstrate that, on the one hand, this flat film structure indeed can realize enhanced focusing; on the another hand, Varying thickness of Ag film may receive different focusing effect; the lens’s focus shift to the far-field from near-field slowly with a increase in Ag film thickness; the size of focus in near-field is small than one wavelength, but in the far-field is slightly larger.2. In order to improve the thin film photoelectric conversion efficiency of solar cells, this paper examines a metal nanoparticles embedded composite solar cell materials. With the help of three dimensional electromagnetic simulation software, the metal-organic hybrid thin films structure was established in the thesis; and then, by means of simulation, there are comparative analyses of metal particles on the solar cell efficiency of photon absorption. The calculation data show that, metal nanoparticles can play an enhanced role of photon absorption due to the LSP resonance effect; in the organic material, changing the location, size, shape, and array period, the electromagnetic field distribution will be changed, and then the enhanced photon absorption effects are different. Finally, through a series of comparative analysis, the thesis summarizes an optimal array layout of metal nanoparticles, providing a pretty good foundation for the design of hybrid organic thin-film solar cells.更多还原