Ternary copper-tungsten-disulfide nanocube inks as catalyst for highly efficient dye-sensitized solar cells

In this report, ternary copper-tungsten-disulfide (Cu2WS4) nanocube inks are successfully synthesized via colloidal synthesis process, utilizing metal chloride as cation sources, sulphur powder combined with oleylamine as coordinating solvent and ligand, and employed, for the first time, as catalyst for counter electrode (CE) to build up a low-cost/high-efficient dye-sensitized solar cell (DSSC). The composition, structure and morphology of these nanocubes are characterized by performing pertinent analyses. The experimental results indicate that the nanocubes are single phase, nearly stoichiometric composition and a mean size of 200 nm. From outstanding electrochemical performance, Cu2WS4 CE exhibits excellent catalytic activity towards iodine redox couples in the electrolyte and fast electron-transfer at the interfaces of CE/electrolyte owing to its larger surface area, more conductive network, lower charge transfer resistance and strong adherence of CWS nanocubes on substrate compare to Pt. The CWS-based cell displays a higher power conversion efficiency of 8.94% than that with Pt CE (8.00%), as well as an excellent reversibility/durability with long-term stability. The newly developed material confirms as valuable alternatives to Pt-free CEs for reduction in DSSCs and is of peculiar interest because of its low-cost, high stability simple fabrication process and impressive photovoltaic performance.