Electrochemical study on poly(paraphenylene)/poly(3-octylthiophene) bilayer electrodes

Bilayer electrodes of poly(paraphenylene), PPP, and poly(3-octylthiophene), POT, were studied by cyclic voltammetry and electrochemical impedance spectroscopy. The bilayer electrodes were made electrochemically on a Pt electrode from the dimer in case of PPP and from the monomer in case of POT. The electrolyte medium was TBABF4 (0.1 M) in acetonitrile. The redox response from the bilayers was compared with respective single layer film electrodes. The charge involved in the redox response of a PPP film is approximately one fifth of the charge involved in a POT film of similar thickness. The redox response of the bilayer combination Pt/PPP/POT involves a total charge that is up to two times higher than the charge obtained from adding the response of the corresponding single layers. It was found that the POT layer, when deposited as the outer layer, was controlling the ion transfer through the bilayer and functioned as a semipermeable membrane for ions