Cu₂ZnSnS₄ thin film solar cell fabricated by magnetron sputtering and sulfurization

In this work, sulfurizing metal precursors prepared by magnetron sputtering was applied in Cu2ZnSnS4 (CZTS) thin film fabrication. Three precursor structures, namely substrate/ Zn/(Cu&Sn), substrate/Zn/Cu/Sn/Cu and substrate/Zn/Sn/Cu, were compared for their synthesized CZTS film quality. It is notable that CZTS film made of the precursor structure of substrate/Zn/ (Cu&Sn) has the best film quality with no obvious voids and biggest average grain size. When applying this precursor structure into device fabrication, a working CZTS device with an efficiency of 2.26% was made. The impact of metal precursors on the structural property of CZTS film were characterised by SEM, XRD, Raman and TEM. Thick MoS2 interfacial layer (∼200nm) between absorber and back Mo contact and ZnS formed in the front and back absorber regions are the possible reasons limiting short-circuit current and fill factor of the cell.