XII Iberian Meeting of Electrochemistry XVI Meeting of the ...

XII Iberian Meeting of Electrochemistry & XVI Meeting of the Portuguese Electrochemical Society O C 01
Electrosynthesis and Redox Conversion of
Poly(3,4-ethilenedioxythiophene) Films An Ellipsometric
and Probe Beam Deflection Study
A. I. Melato, J. P. Correia, L. M. Abrantes
CQB, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa,
Campo Grande, 1749-016 Lisboa, Portugal
aimelato@fc.ul.pt
Poly(3,4-ethilenedioxythiophene) (PEDOTh) has been the subject of intense research
devoted to the influence of the electropolymerization conditions on the films properties
[1-3]. Despite the valuable data gathered by purely electrochemical techniques on the
charge transfer processes during the synthesis and redox conversion of the polymers,
they are unable to provide insights about the structural features of the films and on the
nature of the species involved in the redox processes. Such information can be achieved
by the powerful association of optical techniques with the electrochemical ones. In-situ
Ellipsometry and Probe Beam Deflection (PBD) have been successfully employed to
evaluate the dielectric properties and mass fluxes taking place both during the formation
and electrochemical conversion of several conducting polymers [4-6].
In this work an ellipsometric and PBD study of the electrosynthesis and redox behaviour
of PEDOTh films is presented. Thin polymeric films were generated on platinum
electrodes, from organic solutions of the monomer, under potentiostatic and
potentiodynamic modes, being electrochemically characterized by cyclic voltammetry.
A two-homogeneous phase model has proven to be appropriate to describe the films
optical properties and the mathematical tool of temporal convolution was employed to
determine the extent and nature of each individual participation for the overall mass
transfer. The combined electrochemical and optical information, collected for films
prepared with distinct growth charges and in different supporting electrolytes, allowed
to discuss the values of the local dielectric properties of the polymer and their relation
with the mass transfer phenomena taking place during the PEDOTh formation and in the
course of the doping/undoping processes.
References
[1] Melato, A. I.; Mendonça, M. H.; Abrantes, L. M. J. Solid State Electrochem. 2009, 13, 417.
[2] Aubert, P.-H.; Groenendaal, L.; Louwet, F.; Lutsen, L.; Vanderzande, D.; Zotti, G. Synth.
Metals 2002, 126, 193.
[3] Niu, L.; Kvarnström, C.; Ivaska, A. J. Electroanal. Chem. 2004, 569, 151.
[4] Correia, J. P.; Vieil, E.; Abrantes, L. M. J. Electroanal. Chem. 2004, 573, 299.
[5] Abrantes, L. M.; Correia, J. P. Electrochim. Acta 1999, 44, 1901.
[6] Melato, A. I.; Correia, J. P.; Abrantes, L. M. J. Electroanal. Chem.,
doi:10.1016/j.jelechem.2010.02.025.
September, 811, 2010. ISEL - Lisbon 40