Enhanced photovoltaic performance of dye-sensitized solar cells based on electrodeposited sulfur-doped MSex (M=Co, Ni) films

Abstract Rational design of ternary transition metal sulfoselenide films by an electrodeposition technique remains a critical challenge to further improve their catalytic activity. This study reports a fabrication approach of sulfur-doped MSex (M = Co, Ni) films, which are directly employed as efficient counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The morphology and electronic structure of sulfur-doped MSex films are controlled by adjusting the molar ratio of S/Se in their electrodeposition solutions. It is found that sulfur-doped MSex films exhibit favorable electrocatalytic activity for the reduction of I3−, owing to their more exposed activity sites and strong charge-transfer capability. Furthermore, the DSSC fabricated with the optimized sulfur-doped CoSex (sulfur-doped NiSex) CE has achieved the highest power conversion efficiency (PCE) of 7.44% (7.54%) than that of the DSSC fabricated with platinum (Pt) CE (6.38%). The results demonstrate that sulfur-doped MSex films have applied as the attractive low-cost CEs with outstanding electrocatalytic activity for DSSCs.