Honeycomb-like CoS Counter Electrodes for Transparent Dye-Sensitized Solar Cells

In this study, a transparent CoS counter electrode (CE) fabricated by potentiodynamic deposition was incorporated in a Pt-free dye-sensitized solar cell (DSSC). The CoS CE fabricated by potentiodynamic deposition was observed with high transparency and honeycomblike morphology. Thus it exhibited a low charge-transfer resistance of ∼1.45 Ω cm 2 in comparison with a sputtered-Pt CE (∼2.03 Ω cm 2 ). The DSSC assembled with the CoS CE showed a superior photovoltaic conversion efficiency of 6.01% to that with the sputtered-Pt CE (5.71%) due to the higher photocurrent density (14.17 mA cm −2 ) under full sunlight illumination (100 mW cm −2 , AM 1.5G).