Interactions in Electrodeposited Poly-3,4-Ethylenedioxythiophene—Tungsten Oxide Composite Films Studied with Spectroelectrochemistry

Abstract

Cyclic voltammograms and optical absorption spectra of PEDOT/WO3 composite films were recorded in order to identify possible interactions and modes of improved performance of the composite as compared to the single materials. Changes in the shape of redox peaks related to the W(VI)/W(V) couple in the CVs of WO3 and the composite PEDOT/WO3 films indicate electrostatic interactions between the negatively charged tungsten oxide species and the positively charged conducting polymer. Smaller peak separation suggests a more reversible redox process due to the presence of the conducting polymer matrix, accelerating electron transfer between tungsten ions. Electronic absorption spectra of the materials were analyzed with respect to changes of the shapes of the spectra and characteristic band positions. There are no noticeable changes in the position of the electronic absorption bands of the main chromophores in the electronic spectra of the composite film. Obviously, the interactions accelerating the redox performance do not show up in the optical spectra. This suggests that the existing electrostatic interactions in the composite do not significantly change the opto-electronic properties of components of the composite but resulted in the redistribution of fractions of polaron and bipolaron forms in the polymer.

Spectroelectrochemistry of Electroactive Polymer Composite Materials

“…The using of optical spectroelectrochemical studies for characterization of PEDOT composites with WO 3 [ 21 ] indicated the redistribution of the fractions of different oxidized forms (polarons and bipolarons) in PEDOT/WO 3 films. In [ 22 ] the spectroelectrochemical behavior of PEDOT/GO composites were studied in an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) as well as in acetonitrile and aqueous electrolytes.…”

“…Incorporation of nanostructured inorganic compounds into the EA polymers combines valuable features of the organic and inorganic components in a single material and modifies the properties of the EA polymers, leading to the development of multifunctional devices [ 20 ]. The synthesis of nanostructured metal oxide–EA polymer composites lead to synergistic enhancement of their electrochromic and pseudo-capacitive properties [ 21 ]. Novel nanostructured carbon materials (nanotubes, graphene) can significantly improve the electrical conductivity and electrochemical performance of PEDOT in areas such as the stability of electrochromic characteristics, coloration efficiency, and switching time due to an important role of the electron transfer in the bulk of PEDOT films [ 22 , 23 ].…”

o-Toluidine in electrochemistry – an overview

“…The electrochromic behavior of a composite of WO 3 and a copolymer of aniline and o-toluidine has been reported; the reasons for using a copolymer instead of homopolymers (see [205]) are not apparent [206]. The electrochromic performance of oligoaniline-containing polyurea's end-capped with various functional groups has been examined; the use of o-toluidine as an end-group apparently has no particular advantage [207].…”