Research of ZnS as a buffer layer for CIGS solar cells

Normally, CdS film is used as the buffer layer in the fabrication of copper indium gallium selenide solar cells. These solar cells can reach an efficiency of 10.3% when produced by a non-vacuum process. However, this is a very toxic process. In this study, we propose using a nontoxic zinc sulfide (ZnS) buffer layer which is deposited by chemical bath deposition. It took only 15 minutes to reach a ZnS thickness of 50nm and the transmittance of the finished device was higher than 80%. The back contact of the Mo layer sheet resistivity is 0.22 (Omega/square). The precursor solution for the cell fabrication was prepared from anhydrous hydrazine. The film was then deposited by spraying and finally heated rapidly to 520 without external selenization.