Above 10% efficient electrodeposited Cu₂ZnSn(S,Se)₄ solar cell achieved by modifying precursor

Electrodeposition is a promising method to fabricate Cu₂ZnSn(S,Se)₄ (i.e., CZTSSe) absorber layer thanks to its many advantages such as low-cost and large-scale. However, the secondary phases and intrinsic defects in electrodeposited CZTSSe solar cells inevitably limit the photoelectric performance. Herein, two different kind of precursor films (binary-ternary selenide vs. quaternary selenide) are deliberately fabricated and the effect of these precursors on the secondary phases and intrinsic defects of CZTSSe absorber layer are investigated comprehensively. The absorber layer obtained from binary-ternary selenide precursor has a small amount of ZnSe secondary phases and Cu_Sn deep defects, whereas that obtained from the quaternary selenide precursor exhibits the favorable V_Cu shallow defects, which is beneficial to the efficiency improvement in CZTSSe. Based on the quaternary selenide precursor film, the CZTSSe solar cell with 10.03% total area efficiency (the active area efficiency is 10.9%) was obtained. This is the highest efficiency of CZTSSe solar cells prepared by the electrodeposition method.