Growth mechanisms, morphology, and electroactivity of PEDOT layers produced by electrochemical routes in aqueous medium

The electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT) in sodium poly(styrene-4-sulfonate) (NaPSS) polyelectrolyte aqueous solution was studied in order to establish a direct relationship between the synthesis conditions and the growth mechanisms of the polymeric film. The final morphology, the polymer structure and the electroactivity of the produced PEDOT:PSS layers have also been investigated in order to achieve a comprehensive understanding of the physico-chemical properties of the material. At this aim the current-time transients referred to the growth best conditions have been fitted using a mathematical equation that considers two contributions corresponding to 3D progressive nucleation under diffusion control and to 3D instantaneous nucleation controlled by charge transfers. The atomic force microscopy study performed on the polymeric films at various stages of electrodeposition supported the proposed growth model. The structural feature and the electrochemical performance of the PEDOT:PSS systems have been studied by Raman spectroscopy and cyclic voltammetry. These studies showed that the adopted experimental conditions allow one to grow PEDOT:PSS films in their oxidized state and characterized by high-capacitive properties. © 2008 Elsevier B.V. All rights reserved.