Application of Transparent Cobalt Sulfide Counter Electrodes in Dye-sensitized Solar Cells

Cobalt sulfide nanomaterials are considered as important counter electrode materials for dye-sensitized solar cells. A potential reversal electrodeposition technique was applied to fabricate transparent cobalt sulfide film with fluorine-doped tin oxide glass as substrate. The experimental results demonstrate that the surface morphology of cobalt sulfide films is mainly dependent on the pH value of plating solution. The thickness of cobalt sulfide films can be effectively controlled by electrodeposition cycles. Then, cobalt sulfide films were used as counter electrodes of dye-sensitized solar cells. Electrochemical measurements prove that cobalt sulfide counter electrodes exhibit high electrocatalytic activity. In particular, under electrodeposition condition of pH 7.2 and 12 cycles, cobalt sulfide counter electrode composed of the nanosheet structure exhibits higher electrocatalytic activity than platinum electrode, due to the increase of electrocatalytic active sites. Meanwhile, remarkable photoelectrical conversion efficiency of the dye-sensitized solar cell based on cobalt sulfide counter electrode is up to 7.26% with an average value of 7.18% for ten devices, which is higher than that of the dye-sensitized solar cell equipped with platinum electrode(6.94%).