摘要
太阳能的有效利用能够缓解当前的能源危机和环境污染这两大社会问题。太阳能电池可以直接将太阳能转换为电能，但是在当今社会中并没有得到广泛应用，究其主要原因是太阳能电池的转换效率过低和生产成本过高。因此，提高转换效率和降低生产成本是今后太阳能光伏技术发展的方向和目标。微纳结构在光伏器件上的应用能够极大地减小电池吸收层的厚度，从而降低其生产成本。为了提高太阳能电池的光电转换效率，很多研究工作都集中在新型光伏材料和陷光结构的研发当中。
本文以太阳能电池的陷光结构为研究对象，设计出了纳米针光栅阵列和倾斜纳米线阵列的新型陷光结构，并且还建立了球形金属颗粒的表面等离子模型。通过数值仿真，对它们进行了光学特性和陷光机理的研究。本文的主要研究内容和结果如下：
项英简历首先，针对GaAs纳米针光栅阵列，系统地研究了光栅阵列的结构参数对光吸收的影响。研究结果表明，光栅阵列的光吸收性能受结构参数的影响很大，经过优化后的光栅结构在所考察的波长范围内可以引起很宽波段内的光吸收增强。在最优参数配置下，纳米针光栅阵列的光吸收率最高可达到98%，与矩形光栅阵列相比提高了20%以上。
其次，提出了倾斜GaAs纳米线阵列的陷光结构。利用有限元方法，研究了倾斜纳米线阵列的直径和填充因子对光吸收特性的影响，并且优化了该倾斜纳米线阵列结构。优化后的倾斜纳米线阵列，总吸收率最
大可达到95%，短路电流可达到30.3mA/cm2。与竖直纳米线阵列相比，倾斜纳米线阵列的光学性能得到了很好的提高，这说明将纳米线阵列做成倾斜结构，可以提高纳米线阵列的陷光能力。
最后，建立了以晶体硅为背景材料的金属颗粒表面等离子陷光模型，并且分析了金属颗粒的镶嵌位置、直径以及填充因子对晶体硅光学特性的影响。结果表明，硅材料的吸收率受金属颗粒直径和填充因子的影响很大，而受镶嵌位置的影响很小。直径和填充因子主要影响吸收峰的数目。为了探究光吸收增强的陷光机制，对吸收峰的产生机理进行了分析。在晶体硅薄膜层里加入金属颗
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粒，能够在一定程度上提高晶体硅的光吸收能力。
关键词：太阳能电池，纳米针光栅，倾斜纳米线，表面等离子，吸收效率
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番茄鱼片>可爱小动物
Abstract
The effective utilization of solar energy can relieve the two social difficult problems of energy shortage and environment pollution. The solar cell can directly convert sunlight into electrical energy,
but now it is not widely applied in our society. The major reason is too low conversion efficiency and too high production cost for solar cell. Therefore, improving conversion efficiency and reducing cost is and remains to be a direction and goal of photovoltaic technology development. The application of micro-/nano-structure in the photovoltaic devices can greatly reduce the thickness of the absorbing layer, thereby reducing the production cost. In order to improve the conversion efficiencies of solar cells, a great deal of rearch work has been focud on the new photovoltaic materials and light trapping structures.
This thesis choos light trapping structures of solar cells as the rearch object, the new trapping structures bad on needle profile grating arrays (NPGAs) and inclined nanowire arrays (NWAs) are designed. In addition, the surface plasmon model of spherical metal particles also is built. Through numerical simulation, we conduct a study about optical properties and light-trapping mechanism. In this thesis, the main rearch contents and the results are as follows:
Firstly, for the GaAs NPGAs, the influence of structure parameters such as taper angle, filling factor and height on the light absorption has been systematically studied. The light absorption performance of NPGAs is nsitive to its structure parameters. The optimized NPGAs can lead to broadband optical absorption enhancement throughout the wavelength range studied. The maximum absorption
efficiency of NPGAs with optimal parameters can achieve 99%, which is over 20% higher than that of rectangular grating counterpart.
工程承包合同范本Secondly, the inclined GaAs NWAs as light absorbing structure for solar cells are propod. By using the finite element method (FEM), the influence of diameter and filling factor of inclined NWAs on the optical absorption properties is investigated, and the optimal geometric parameters of the propod structure are酸辣鸡脚
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determined. The absorption profiles at different wavelengths and angle-dependent properties of inclined NWAs are also evaluated. The optimized NWAs yields a maximum absorption efficiency of 95% and a photocurrent of 30.3mA/cm2, which is superior to the optical properties of vertical NWAs. This demonstrates the light-trapping ability enhancement of inclined NWAs.
Finally, the light-trapping model of Ag metal particles surface plasmon with crystalline silicon as background material is established, and the effect of location, diameter and filling factor of metal particles on the optical properties of crystalline silicon thin film are analyzed. The results reveal that the light absorption of crystalline silicon is nsitive to the diameter and filling factor of metal particle
s, but not nsitive to its location. The diameter and filling factor mainly affect the number of absorption peaks of crystalline silicon absorption spectrum. The light-trapping mechanism at the absorption peaks is analyzed. Adding metal particles into crystalline silicon thin film can improve the light absorption ability of silicon absorbing layer.
Keywords: solar cells, nanoneedle grating, inclined nanowire, surface plasmon, absorption efficiency
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八月流火
目录
1 绪论 (1)
1.1 课题研究背景与意义 (1)
热枕的意思
1.2 太阳能电池的发展历程 (2)
1.3 太阳能电池的发展现状 (4)
1.4 陷光结构的研究进展 (6)
1.5 本文结构安排 (7)
2 数值建模理论及方法 (9)
2.1 太阳能电池的基本原理 (9)
2.2 光子晶体概述 (12)
2.3 数值建模工具与方法 (13)
2.3.1 COMSOL Multiphysics软件概述 (13)
2.3.2 有限元方法概述 (14)
3 基于光栅阵列太阳能电池光学性能研究 (16)
3.1 引言 (16)烫伤宝
3.2针状纳米光栅的制备 (17)
3.3 GaAs纳米针光栅的光学特性分析 (18)
3.3.1 仿真结构与方法 (18)
3.3.2 尖角对纳米针光栅吸收率的影响 (19)
3.3.3 填充因子对纳米针光栅吸收率的影响 (21)
3.3.4高度对纳米针光栅吸收率的影响 (22)
3.3.5 纳米针光栅与矩形光栅吸收谱的比较 (23)
3.4 本章小结 (24)
4 基于纳米线阵列太阳能电池光学特性研究 (26)
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