非晶硅太阳电池宽光谱陷光结构的优化设计

摘要

Light trapping is one of the key issues to improve the light absorption and increase the efficiency of thin film solar cell. In this paper, a novel combined light trapping structure consisting of back one-dimensional (1D) Ag nano-grating and front conformal antireflective coating is proposed for amorphous silicon (α-Si) thin film solar cell. By a numerical simulation based on the finite element method, the effect of the combination on the light absorption ofα-Si solar cell is investigated, and the Ag nano-grating parameters are optimized. The results show that the combined light trapping structure can enhance broadband absorption in thin-film solar cell. For theα-Si solar cell with the combined structure at P=600 nm, H=90 nm, and W=180 nm, the integrated absorption is enhanced by 103%under AM1.5 illumination at normal incidence in a wavelength range of 300-800 nm, and the photon absorption rate is increased by 300% in a long-wavelength range of 650-750 nm compared with the reference cell. We discuss the physical mechanism of absorption enhancement in different wavelength ranges from the electrical field amplitude distributions in the solar cells. In addition, the solar cell with the combined structure is much less sensitive to the angle of incident light.%陷光是改善薄膜太阳电池光吸收进而提高其效率的关键技术之一.以非晶硅(α-Si)薄膜太阳电池为例,设计了一种新的复合陷光结构：在Ag背电极与硅薄膜之间制备一维Ag纳米光栅,并通过保形生长在电池前表面沉积织构的减反膜.采用有限元数值模拟方法,研究了该复合陷光结构对电池光吸收的影响,并对Ag纳米光栅的结构参数进行了优化.模拟结果表明：该复合陷光结构可在宽光谱范围内较大地提高太阳电池的光吸收；当Ag纳米光栅的周期P为600 nm,高度H为90 nm,宽度W 为180 nm时,在AM1.5光谱垂直入射条件下α-Si薄膜电池在300-800 nm波长范围内总的光吸收较无陷光结构的参考电池提高达103%,其中在650-750 nm长波范围内的光子吸收率提高达300%以上.结合电场强度分布,对电池在各个波段光吸收提高的物理机制进行了分析.另外,该复合陷光结构的引入,还较大地改善了非晶硅电池对太阳光入射角度的敏感性.