One-step in situ growth of Co9S8 on conductive substrate as an efficient counter electrode for dye-sensitized solar cells

Abstract

Cobalt sulfide counter electrodes for the dye-sensitized solar cell (DSSC) were successfully prepared on fluorine-doped tin oxide (FTO) glass substrates by a facial one-step in situ solvothermal method. The influences of prepared temperature on the synthesized phase, surface morphology, electrocatalytic, and photovoltaic performances of the cobalt sulfide counter electrodes were investigated with X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Tafel, and photocurrent density–voltage (J–V) measurements. The results indicated that very thin Co9S8 nanoparticle thin films grew on the FTO substrates and the Co9S8 counter electrode prepared at 180 °C showed superior electrocatalytic activity, chemical stability, and photovoltaic performance. The DSSC based on the Co9S8 counter electrode prepared at 180 °C exhibited an efficiency of 6.59 % which was comparable to the solar cell based on the sputtering Pt counter electrode (6.82 %). It indicated that Co9S8 in situ growing on FTO glass substrate at 180 °C is a potential candidate to replace Pt as a low-cost and efficient counter electrode of DSSC.