Improvement of the open-circuit voltage of Cu2ZnSnS4 solar cells using a two-layer structure

In Cu2ZnSnS4 (CZTS) photovoltaic cells, a low open-circuit voltage (VOC) principally causes low conversion efficiency. We investigated the deposition of a CZTS layer by a two-layer process to improve the VOC of the CZTS cells. In this process, the first CZTS layers near a Mo electrode have a high Cu content and the second layer near the surface has a low Cu content. The two-layer process improved the VOC of the CZTS cells from 0.66 to 0.78 V. Finally, the best CZTS cell showed a conversion efficiency of 8.8%.

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