High-Performance Carbon Black-Based Counter Electrodes for Copper (I)/(II)-Mediated Dye-Sensitized Solar Cells

Carbon black (CB) is a readily available, inexpensive carbonaceous material with good catalytic activity, which has been utilized alone or in composites to fabricate highly efficient counter electrodes (CEs) for dye-sensitized solar cells (DSSCs) employing copper redox couple. First, the catalytic activities of the CEs with various CB layers were evaluated and the results reveal that the number of CB layers is an important factor determining the electrochemical behaviors of the CEs. At the optimal CB layers, the CE has an electrocatalytic activity higher than that of the Pt CE and the power conversion efficiency (PCE) of the corresponding DSSC (8.58%) sensitized by Y123 is also higher than that of the cell using Pt (6.89%). To further increase the performance of the CEs, a poly(3,4-ethylenedioxythiophene) (PEDOT) film is deposited on the CB/FTO CEs, forming PEDOT/CB/FTO composite CEs. It shows that the PEDOT/CB/FTO CEs have even higher electrocatalytic activity than the plain CB, PEDOT, and Pt ones. By using these PEDOT/CB/FTO CEs, a PCE of 10.08% can be achieved. Under room light conditions, the cells can also achieve a high PCE of 26.21% (1500 lux). The cells using the composite CEs have good stability.