Fabrication of Cu2ZnSnS4 thin film solar cells by sulfurization of electrodeposited stacked binary Cu–Zn and Cu–Sn alloy layers

• Cu–Zn and Cu–Sn stacked binary alloy layers were electrodeposited on glass/Mo.
• The layers were sulfurized to form Cu2ZnSnS4 absorber layers for solar cells.
• The absorbers exhibit densely packed grains with minor ZnS secondary phase.
• The best cell based on the absorbers has achieved an efficiency of 3.67%.

Kesterite Cu2ZnSnS4 (CZTS) thin films have been fabricated by an electrodeposition route via sulfurizing sequentially electrodeposited Cu–Zn and Cu–Sn stacked binary alloy layers. The CZTS films exhibit densely packed grains with only minor ZnS secondary phase. Photovoltaic device with the structure of ITO/i-ZnO/CdS/CZTS/Mo/Glass shows the highest power conversion efficiency of 3.67%. The limiting factors of the efficiency are the high series resistance and recombination rate. The ZnS phase, voids at the Mo/CZTS interface and high resistance MoS2 layer have been considered to lead to high series resistance and thereby low JSC and FF.