A robust and low-cost strategy to prepare Cu2ZnSnS4 precursor solution and its application in Cu2ZnSn(S,Se)4 solar cells

The metal chalcogenides are excellent choices as absorbers and buffer-layers in thin film solar cells. Versatile chemical approaches provide endless possibilities to prepare metal sulfide precursor solutions. Recently, Cu2ZnSnS(Se)4 thin films have played an important role in fabricating low-cost and high-efficiency solar cells. Here, we present a robust and low-cost 1,2-ethanedithiol/ethanolamine/2-methoxyethanol ternary solution process to prepare Cu2ZnSnS4 precursor solution and high-quality Cu2ZnSnS4 thin films. Low-cost Cu2O, ZnO and SnO are used as the raw materials, which can be easily dissolved in the 2-methoxyethanol solution of 1,2-ethanedithiol and ethanolamine at room temperature in air. By tuning the composition of the Cu2ZnSn(S,Se)4 thin film with a selenization process, an active-area power conversion efficiency of 7.34% has been achieved for Cu2ZnSn(S,Se)4 solar cell.