衍射光栅和光子晶体增强晶体硅薄膜太阳电池光俘获的模拟

Simulation of Enhancing Light Trapping in Crystalline Silicon Thin Film Solar Cells with Diffraction Gratings and Photonic Crystals

提出了一种可以吸收宽光谱的晶体硅薄膜太阳电池结构，其中增透膜为三角形衍射光栅，背反射层由以晶体硅为背景的三角晶格的空气圆柱形光子晶体组成。采用严格耦合波理论和平面波展开法，模拟研究了衍射光栅和光子晶体对提高电池吸收率的影响。结果表明，入射角度在0°～60°之间，增透膜在380～1100nm波长范围内存在高透射率，背反射层在800～1100nm波长范围内存在高反射率。对于有源层厚度为20μm的晶体硅薄膜太阳电池，在入射波为TM偏振状态下，自然光垂直入射时，三角形衍射光栅使光吸收率增加18％，二维光子晶体使光吸收率增加6％。有增透膜和背反射层的晶体硅薄膜太阳电池，当入射角度小于60°时，在380～850nm波长范围内平均吸收率为87．6％，在850～1000nm波长范围内平均吸收率为49％。

A structure of crystalline silicon thin film solar cells are proposed, which can absorb broadband spectrum. The antireflection （AR） coating is triangular diffraction grating and the back reflection layer is composed of air column photonic crystal （PC） of triangular lattice on the background of crystalline silicon. The influences of the diffraction grating and PC on the enhancement of the optical absorption in the cell are simulated using the rigorous coupled wave analysis and plane wave theory method. The results show that for the incident angles of 0°-60°, the AR coating has low reflection within the wavelength range of 380--1100 nm and the back reflection layer has high reflection within the wavelength range of 800- 1100 nm. For the c-Si thin film solar cell with an active layer thickness of 20 μm, under the TM polarization state of the incident wave and when the white light is at a vertical incidence, the light absorption rate is increased by 18% from the triangular diffraction grating and by 6 % from the two dimensional PC. For the crystalline silicon thin film solar cells with AR coating and the back reflection layer, when the incident angle is less than 60%, the average absorption rate is 87. 6% in the wavelength range of 380-850 nm and 49% in the wavelength range of 850-1000 nm.