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Study of silicon thin film solar cells with different back-reflectors


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In this study, hydrogenated amorphous silicon (a-Si:H) single junction and amorphous/microcrystalline silicon tandem (a-Si:H/µc-Si:H) solar cells with different back-reflectors (BRs) are systematically investigated. A novel white polyvinyl butyral (PVB) foil was used as BR. In addition, the specular aluminum (Al) films and rough Al films were deposited on back float glasses as BRs as well, which were integrated onto the front glass covered with solar cells by laminating with a transparent PVB encapsulation foil. It is found that both types of solar cells (a-Si:H and a-Si:H/µc-Si:H) with white PVB foil BRs show a higher short circuit current density (Jsc) compared to the cells with a specular Al BR. It is mainly due to a high light scattering of white PVB foils. Moreover, the cell with a rough Al film BR shows a low Jsc close to that of cell without any BRs. The great light losses inside the solar cell may be mainly caused by the plasmonic absorption on the rough Al film surface. An a-Si:H solar cell of 8.3% and an a-Si:H/µc-Si:H tandem solar cell of 10.1% were obtained, in which the white PVB foils were used as BRs.