Dependence of the Electrochemical Behavior of Poly(N-Phenylpyrrole) Films on the Type of Anion and Solvent Used in the Electropolymerization

The mass transport behavior during the redox reaction of poly(N-phenylpyrrole) (PPhPy) films in propylene carbonate (PC) and acetonitrile (AN) solutions has been studied using the cyclic electrochemical quartz crystal microbalance (EQCM) technique and the electrochemical impedance technique. It was found that the type of dopant anion and solvent used in the electropolymerization affects the amount and the direction of solvent transport during the redox reaction of a PPhPy film. It was also shown that the charge capacity and ionic resistance of a PPhPy film depends highly on the type of dopant anion and solvent used in the electropolymerization. The PPhPy film grown in a PF₆^--containing solution shows larger charge capacity and lower ionic resistance than the film grown in a ClO₄^--containing solution. Moreover, the PPhPy film grown in a PC solution shows similar to or larger charge capacity and lower ionic resistance than the film grown in an AN solution. These dependences on the electropolymerization condition were discussed in connection with the morphology of a film.