Design of WSe2/MoS2 Heterostructures as the Counter Electrode to Replace Pt for Dye-Sensitized Solar Cell

This work reports fabrication of van der Waals interacted WSe2/MoS2 heterostructures on fluorine-doped tin oxide substrates by physicochemical routes. Structural confirmations were performed with Raman scattering and X-ray diffraction, and interfacial structure was investigated using X-ray photoelectron spectroscopy depth profiles. The fabricated WSe2/MoS2 heterostructures were successfully employed as counter electrodes for a dye-sensitized solar cell (DSSC), for the first time. The fabricated WSe2/MoS2 heterostructure counter electrode using assembled DSSC achieved 8.44% maximum power conversion efficiency, comparable to conventional high cost Pt (8.73%). Electrochemical voltammetry, impedance, and Tafel results confirmed the benefits of heterostructure formation to generate interfacial conduction and active facet sharing, thereby improving triiodide reduction catalytic activity. These outcomes open a pathway to fabricate heterostructures as DSSC counter electrodes with effective performance.