Incorporating conductor paste in a low-temperature fabrication process for large mesoporous carbon counter electrode in dye-sensitized solar cells

A novel silver conductor paste modified mesoporous carbon (SCP-MC) counter electrode has been fabricated at low temperature using a large pore MC as catalytic material and the SCP as binder. The efficiency of dye-sensitized solar cells (DSCs) employing the SCP-MC counter electrode reaches the maximum of 5.93% when the SCP content is 6 wt.%, which is 15.4% higher than that of DSCs with a pure MC counter electrode. The improved efficiency mainly results from the enhancement in the fill factor and the short-circuit photocurrent density. Electrochemical impedance spectroscopy (EIS) reveals evident decreases in charge transfer resistance, ohmic serial resistance and Nernst diffusion impedance of the SCP-MC electrode with the SCP content increasing. The contacts among the MC particles and between the catalytic film and the substrate are improved by introducing the SCP, which play a key role in reducing the impedance parameters of the SCP-MC electrode and further improving the photovoltaic parameters of the cells. Especially, the DSCs with the optimum SCP-MC electrode have comparable efficiency to the DSCs with Pt electrode under the same conditions. The high performance of the SCP-MC electrode can be attributed to the favorable characteristics of the MC, such as large sized mesopores, high surface area and low crystallinity as well as the high quality catalytic film caused by adding the SCP.