Research Of Optical Design For Silicon Thin-film Solar Cells By Rigorous Coupled-wave Analysis

In this paper, the main research is optical design of thin film solar cell. The structure of solar cell is calculated by using rigorous coupled-wave analysis (RCWA). The structure of solar cell is made of diffraction characteristics of gratings and light trapping properties of photonic crystals, which lengthened the optical path and increased the absorption of solar light. The main contents are as follows:A rectangular indium tin oxide (ITO) transmission grating is numerically simulated by RCWA in TE polarization and in TM polarization respectively. The diffraction efficiency of TE polarization is superior to the diffraction efficiency of TM polarization, and then the diffraction property is discussed in the TE polarization. In TE polarization, the diffraction efficiency of the optimized rectangular grating can be reached by above90%in the range of the wavelength0.6155-0.63um and in the range of incident angle27-31°. It is important to obtain high diffraction efficiency of solar cell surface rectangular ITO transmission grating.A polycrystalline silicon thin film solar cell consisting of irregularly shaped DBR is designed. By using plane wave expansion method (PWM) and RCWA, energy band of irregularly shaped DBR and absorption of the solar cell is calculated respectively. The results show that, for the TE-polarization, the average of the light absorption of solar cell with the optimized structure can be reached about90%in the wavelength range from400to700nm. What’s more, the average absorption is also very high in TE polarization case. The irregularly shaped DBR is to broaden the reflection range, to increase absorption, and to improve light trapping ability of the solar cell.A new type of the amorphous silicon thin-film solar cell with nested triangle grating structure was proposed. The ITO layer, a-Si layer, ZnO layer, and Ag layer was respective designed by using Rigorous Coupled Wave Analysis. In the meantime, the light absorption of the optimized solar cell is calculated. The result shows that, compared the structure of solar cell with optimized AR coating and the same thickness of flat anti-reflective coating, the absorption is average increased by25%. Using periodic grating structure of the optimized solar cell, the light absorption is average increased by21.15-48.13%, especially in the long wavelength of0.6-0.84μm. In addition, the absorption of optimized solar cell is about90%in range of incident angle0-80°and in the wide wavelength range of0.3-0.8μm; when the incident wavelength is0.4μm,0.5μm,0.6μm,0.7μm, respectively, the absorption of optimized solar cell is nearly reached by1in the range of incident angle0-70°...