Investigation of low cost carbonaceous materials for application as counter electrode in dye-sensitized solar cells

The structural and morphologic properties of different carbonaceous materials were studied by X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET) porosimetry and transmission electron microscopy (TEM) analyses. The electrochemical behaviour of these powders used as counter electrode in dye-sensitized solar cells (DSSCs) was investigated by polarization experiments and electron impedance spectroscopy. Results were compared with DSSC using Pt as counter electrode. All DSSCs based on the carbonaceous materials showed conversion efficiencies higher than those equipped with Pt. Among the various carbon materials investigated, Acetylene Black in conjunction with graphite showed the best performance. This was interpreted from the physico-chemical analysis as due to a compromise between pores accessibility for the I-3(-) reactant presents in electrolyte and appropriate surface graphiticity index of this carbonaceous material. A high degree of graphitization for the carbon black was found to enhance electron conduction and charge transfer properties.