Solution-Based in-situ Synthesis of Transition Metal Sulfides as Efficient Counter Electrodes for Dye-Sensitized Solar Cells

Transition metal sulfide films Co-S, Mo-S, and Ni-S have been deposited by spin-coating their precursor solutions followed by a mild thermal treatment. X-ray diffraction results and X-ray photoelectron spectrum demonstrate that the solution-processed Co-S, Mo-S, and Ni-S are composed of CoS2, MoS2, and NiS with NiS2, respectively. Electrochemical characterizations reveal these sulfide films deposited on fluorine doped tin oxide (FTO) glasses as counter electrodes (CEs) show high catalytic activity to I3-species and good electrical conductivity compared to that of conventional Pt/FTO. Photo-electric conversion efficiencies of 6.42 %, 5.82 %, and 5.72% are obtained for the DSSCs adopting Co-S CE, Mo-S CE, and Ni-S CE, respectively, comparable to the device (6.59%) employing Pt/FTO CE.