title: Medium effects on the nucleation and growth mechanisms during the redox switching dynamics of conducting polymers: case of poly(3,4-ethylenedioxythiophene).
abstract: The redox switching dynamics of poly(3,4-ethylenedioxythiophene) (PEDOT) in an acetonitrile solution and a room temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EmiTFSI), are investigated by means of potential step experiments. Redox switching can be viewed as a phase transition in which the nucleation and growth processes occur. We have developed a phenomenological model allowing the determination of the kinetic parameters. Two limiting cases are shown as follows: (i) a progressive and (ii) an instantaneous nucleation. In all cases, the growth process is described in terms of a self-exchange electron transfer reaction. We show that the mechanisms depend upon the medium. In acetonitrile, progressive nucleation and growth occur during oxidation (p-doping), whereas nucleation is instantaneous in the reduction of the PEDOT film. On the other hand, instantaneous nucleation and growth mechanisms are observed for both oxidation and reduction in EmiTFSI. The difference in the mechanisms results from the ionic exchange process associated with electron transfer and the initial structure of the film (open or compact). The influence of the applied potential on the dynamics is analyzed for both media.
authors.affiliation: Interfaces, Traitements, Organisation et Dynamique des Systèmes (ITODYS), CNRS-UMR 7086, Université Paris-Diderot, Bâtiment Lavoisier, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France. hyacinthe.randria@univ-paris-diderot.fr
authors.forename: Hyacinthe
authors.initials: H
authors.lastname: Randriamahazaka
authors.forename: Thomas
authors.initials: T
authors.lastname: Bonnotte
authors.forename: Vincent
authors.initials: V
authors.lastname: Noël
authors.forename: Pascal
authors.initials: P
authors.lastname: Martin
authors.forename: Jalal
authors.initials: J
authors.lastname: Ghilane
authors.forename: Kinji
authors.initials: K
authors.lastname: Asaka
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Lacroix