硅薄膜太阳能电池中硅纳米线形状对光吸收率的影响

The effect of the nanowire shape on the optical absorption of the silicon nanowire film solar cells

为了研究硅薄膜太阳能电池中硅纳米线阵列的光吸收率,利用耦合波分析理论(RCWA),分别研究了按正方形排列的柱形、锥形、柱锥形间隔等3种形状硅纳米线阵列对光吸收率的影响。通过改变3种形状硅纳米线阵列的周期、占空比,分别计算其对应的光吸收率,从中优化得到吸收效率最佳的硅纳米线结构参数,并通过光吸收效率η对硅纳米线结构的光吸收率进行定量分析。结果表明,在一定范围内适当增大硅纳米线结构的周期和占空比,能使得吸收率曲线往长波段处移动,并能有效地增加其光吸收效率η;不同硅纳米线形状获得最大吸收效率时对应的结构参数也不同;3种形状硅纳米线阵列中以锥形硅纳米线的光吸收率最佳。

To study the absorption of the silicon nanowire （SiNW） arrays for silicon thin film solar cells, the RCWA was used to simulate the optical absorption of the SiNW arrays, whose cross section varies from cylindrical to conical shapes. The absorption was calculated in terms of the period and the duty ratio of the SiNW arrays. Optimization of these two parameters was conducted in order to achieve the maximal absorption within solar absorption spectral range by evaluating the ultimate efficiency. The results indicate that the absorption bandwidth significantly shifts toward the long-wave region when the nanowire period and duty ratio increase, the ultimate efficiency could be enhanced effectively with the increase of the SiNW period and duty ratio within certain extents. The shape of the nanowire also plays an important role in determining the maximal absorption. Cone silicon nanowires were found to have the maximal absorption in the three kinds of silicon nanowire shapes.