Cu2ZnSnS4 Thin Film Solar Cells Utilizing Sulfurization of Metallic Precursor Prepared by Simultaneous Sputtering of Metal Targets

Cu2ZnSnS4 (CZTS) thin films were prepared by simultaneous sputtering of metallic targets and sulfurizing a metallic precursor under elemental sulfur atmosphere in a sealed tube. Subsequently, they were applied to the fabrication of thin film solar cells. The precursors with desired compositional ratio and thickness were obtained by controlling the area ratio of sputtering targets and also sputtering parameters. We have succeeded in obtaining high-quality polycrystalline CZTS thin films by sulfurization under a sulfur vapor pressure higher than atmospheric pressure. A CZTS-based solar cell with 3.7% conversion efficiency was obtained from CZTS films sulfurized at 590 °C for 7 min.