Electrochemical impedance spectroscopy and photovoltaic analyses of dye-sensitized solar cells based on carbon/TiO₂ composite counter electrode

The objective of this study is to replace the platinum catalyst normally used in the counter electrode of dye-sensitized solar cells by a low cost activated carbon (AC)/TiO2 nanocomposite. The counter electrodes were prepared by varying the composition of activated carbon (AC) in the AC/TiO₂ nanocomposites. The TiO₂ anatase paste was used as a binder to hold the carbon nanoparticles together. The morphological properties of composite counter electrodes were analyzed by scanning electron microscope. Solar cells with composite counter electrodes were characterized for photocurrent-voltage relation and electrochemical impedance spectroscopy measurements. The results indicate that the efficiency of solar cells is highly dependent on the concentration of activated carbon in the counter electrode. The optimal performance of the solar cell was observed for the counter electrode containing 10% activated carbon showing J_SC = 15.834 mA cm⁻², V_oc = 700 mV, R_s = 49 , FF = 55, and η = 6.04%. These photovoltaic parameters are comparable with J_SC = 14.638 mA cm⁻², V_oc = 810 mV, R_s = 43 , FF = 60, and η = 7.0% for the platinum based dye sensitized solar cell.