Electrochemical impedance spectroscopy of polybithiophene films in an aqueous LiClO4 solution

Polybithiophene (PBT) films (oxidized form), electrochemically deposited on Pt from an aqueous anionic micellar medium, werecharacterized by EIS measurements in 0.3M aqueous LiClO4 at different applied potentials. The EIS data were fitted with an equivalent electrical circuit in order to characterize the PBT electrochemical properties. Our experimental results show that both the double-layer and the film capacitances as well as the charge-transfer resistance decreased with the film thickness, while the diffusive capacitance and the charge-transfer and the pore resistance increased. Increasing the applied potential enhances the double-layer and film capacitances and the charge-transfer and pore resistances, but reduces the diffusive capacitance (with a minimum around the open-circuit potential) and the film resistance.