三維奈米柱與電漿子奈米粒子的薄膜非晶矽氫太陽能電池

Abstract

本論文探究多種型態的非晶矽氫奈米結構單層太陽能電池。奈米尺寸結構十分的具有前途由於其獨特的光與電特性。他們提供有效的方法來增加太陽能電池中的光程，進而增加元件的能量轉換效率。本論文主要區分為兩個主題：電漿子奈米粒子與三維奈米柱結構。 第一部份，將具備多層金奈米粒子的電漿子結構嵌入在透明導電層背反射基板的非晶矽氫太陽能電池被提出證實。藉由光學上研究奈米粒子密度與粒子層數，我們可以調變電漿子的共振頻率，得到最佳的光散射條件。雙層的金奈米粒子結構在光吸收上優於單層的結構。此外，除了光的散射增益，應用高功函數的金奈米粒子可以提升透明導電層與非晶矽氫界面的功函數匹配。 第二部分，以水熱法製備三維氧化鋅奈米柱陣列的非晶矽氫太陽能電池被提出證實。非晶矽氫太陽能電池的吸收層厚度與奈米柱長度的關係被詳細的研究。研究重點放在利用三維奈米柱來達到電性上的薄與光學上的厚，實現高效率的非晶矽氫太陽能電池。 第三部分，微結構結合氧化鋅奈米柱陣列的非晶矽氫太陽能電池被提出證實。高度指向性的氧化鋅奈米柱以水熱法成長於商業化的微結構基板上。表面型態與散射特性跟反應試劑的濃度有相當大的關聯。藉由控制實驗條件，可以成功得到具備花形貌的氧化鋅奈米結構。 第四部分，有了上述的研究成果，結合電漿子金奈米粒子與三維奈米柱陣列的新型態奈米柱結合奈米粒子非晶矽氫太陽能電池被提出證實。利用熱蒸鍍法沉積超薄的金薄膜於奈米柱表面來形成金奈米粒子。電漿子奈米粒子與三維奈米柱的散射特性被系統性的研究。藉由調整最佳化的金薄膜厚度，奈米柱結合奈米粒子非晶矽氫太陽能電池的能量轉換效率可以有效的被改善。

This thesis explores various types of nanostructures in single junction hydrogenated amorphous silicon (a-Si:H) solar cells. The nanometer-sized structures are promising due to their excellent optical and electronic properties. They provide an effective way to increase optical path length inside solar cell, and thus result in improved energy conversion efficiency. This thesis is divided into two primary tasks: plasmonic nanoparticles and three-dimensional nanorods structures. First, the plasmonic-structure incorporated multilayer of Au nanoparticles embedded in the transparent conducting oxide at the back reflector of a-Si:H solar cells is demonstrated. The effect of the nanoparticles density and the number of multilayer of the nanoparticles in tuning the plasmon resonances for better scattering are investigated by measuring optical characteristics. The double-layer Au nanoparticles structure has an advantage over single-layer for harvesting light. In addition to enhanced light scattering, applying high-work-function Au nanoparticles can improve the matching of work function at TCO/a-Si:H interface. Second, the a-Si:H solar cells based on three-dimensional ZnO nanorods arrays prepared by hydrothermal growth is demonstrated. The influence of the absorber layer thickness and rod length on the performance of a-Si:H solar cells are investigated in detail. Focus in on the concept of applying three-dimensional nanorods for electronically thin and optically thick in achieving high efficiency a-Si:H solar cells. Third, the a-Si:H solar cells based on random textures substrates incorporating ZnO nanorod arrays is demonstrated. Highly-oriented ZnO nanorods are grown on textured substrate (Asahi-U glass) through hydrothermal growth. It is found that the surface morphology and diffuse scattering property are strongly dependent on the concentration of reagents. By controlling the experimental conditions, the flower-like ZnO nanostructure is successfully obtained. Fourth, in terms of previous tasks, plasmonic Au nanoparticles and three-dimensional nanorod arrays are combined to demonstrate a new type of nanoparticles decorated nanorods a-Si:H solar cell. The ultra-thin Au film are deposited on the surface of nanorods by thermal evaporation system to form Au nanoparticles. The scattering property between plasmonic nanoparticles and three-dimensional nanorods are investigated systematically. By optimizing thickness of Au metal film appropriately, the improved energy conversion efficiency is obtained for the nanoparticles decorated nanorods a-Si:H solar cell.