Electrochemical impedance spectroscopy study of poly[3,5-dithiophene-2- yldithieno[3,2-b;2′,3′-d]thiophene] P(Th₂DTT)

Electrochemical properties of poly[3,5-dithiophene-2-yldithieno[3,2- b;2′,3′-d]thiophene] film was investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) for the applicability of the system as an electrochemical capacitor. 3,5-Dithiophene-2-yldithieno[3,2- b;2′,3′-d]thiophene (Th₂DTT) was electropolymerized on Pt electrodes with varying thicknesses in two different potential ranges, which provided the polymer films with different structures. Impedance spectra of the films were obtained at dc potentials where they were in the oxidized (p-doped) states. The EIS data were fitted to an equivalent electrical circuit to characterize the electrochemical properties of the electrodes. A good agreement was achieved with the experimental and simulated EIS data. These results imply that the polymeric films provide enhanced capacitance, which make them promising materials in energy-storage devices.