Fabrication and characterization of a multi-walled carbon nanotube-based counter electrode for dye-sensitized solar cells

A counter-electrode (CE) for dye-sensitized solar cells (DSSCs) was prepared by coating a slurry containing acid-oxidized multi-wall carbon nanotubes and nano-graphite powder onto a fluorine-doped tin oxide conducting glass substrate. The samples were characterized by SEM, TEM, EDS and IR spectroscopy. The CE performance in the DSSCs with MgO-doped TiO₂ as the photoanode was investigated by measurements of current-voltage curves, cyclic voltammetry and electrochemical impedance spectroscopy. Results show that the cell with the CE exhibits the best photoelectric properties of all the carbon-based CEs investigated. The short-circuit current density (J_sc) is 4.67 mA/cm², the open-circuit voltage (V_oc) is 0.53 V and photoelectric conversion efficiency is up to 4.10%, which are comparable with those of the Pt-based CE in DSSCs.