异向混合光栅薄膜太阳能电池光吸收分析

Optical Absorption of Anisotropy Hybrid Grating Thin Film Solar Cell

为了分析混合光栅对硅薄膜太阳能电池光吸收的影响,在硅层厚度等效一致的条件下,设计了单一形状、同向和异向混合形状光栅单晶硅太阳能电池结构.利用时域有限差分法分别优化计算了各种混合光栅的最佳尺寸、光生电流密度和光吸收效率,发现异向混合结构的Ag光栅比其他结构具有更好的光吸收能力.通过电磁场强度分布图分析了混合光栅结构的吸收增强机理,并针对异向混合光栅,计算了不同光栅数量组成结构的光生电流密度.同时,利用光吸收增强因子定量分析得出一个三角凸型和一个抛物线凹槽是异向混合光栅最佳数量组合.有规律地改变这种混合光栅的宽度比和高度比,计算光生电流密度.结果发现当宽度比为1∶1,高度比在一个小范围内(0.67～1.86)波动时,这种异向混合结构比平板太阳能电池的光生电流密度提高了62.9%.研究结果可为薄膜太阳能电池的结构和参数设计提供参考.

To analyze the impact of hybrid gratings on silicon thin film solar cells, the crystalline silicon solar cells with mono shape of grating, syntropy and anisotropy shapes of hybrid grating were designed. And the thickness of silicon layer was unified. By finite-difference time-domain method, the optimal sizes, photocurrent densities and optical absorption of hybrid gratings were optimized, respectively. The results showed that the anisotropy hybrid grating had more optical absorption performance than other structures. Through analyzing the electromagnetic field intensities, the mechanism of optical absorption enhancement of hybrid grating structure was found. Also, the photocurrent density with different grating numbers of component structures was calculated for the anisotropy hybrid grating. Simultaneously, the optimum combination of a triangle convex and a parabola convex in anisotropy hybrid grating was quantified by the factor of absorption enhancement. By varying the ratios of width and height regularly, the photocurrent densities were calculated. Results indicated that the photocurrent density of the anisotropy hybrid structure increased by 62.9% relative to a flat solar cell when the ratio of width was set 1:1 and the ratio of height ranged from 0.67 to 1.86. The study can provide a theoretical reference for the structure and parameter design of thin film solar cells.