Hydrothermal growth of MoS2/Co3S4 composites as efficient Pt-free counter electrodes for dye-sensitized solar cells

MoS2/Co3S4 composite films were prepared via a facile one-step hydrothermal method, and used as efficient and low-cost Pt-free counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). Characterizations revealed that Co3S4 and MoS2 were obtained simultaneously during the facile hydrothermal process. The composites afforded a promising synergistic effect on the catalyzing of triiodide reduction. Enhanced electrocatalytic performance of the resultant composite films was confirmed through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses. DSSCs using MoS2/Co3S4 composite CEs outperform the devices with pristine MoS2 or Co3S4 CEs in power conversion efficiency (PCE). Furthermore, a PCE of 6.77% is obtained for the optimized devices using MoS2/Co3S4 composite CEs measured under standard 1 sun illumination (100 mW cm(-2), AM 1.5G), which is comparable to that of the devices fabricated under the same conditions with conventional thermally deposited Pt CEs (7.14%). The results demonstrate that MoS2/Co3S4 composites are promising alternatives to Pt to be applied as CEs for DSSCs.