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Spectroelectrochemistry and Nature of Charge Carriers in Self‐Doped Conducting Polymer
Author(s) -
Volkov Anton V.,
Singh Sandeep Kumar,
Stavrinidou Eleni,
Gabrielsson Roger,
FrancoGonzalez Juan F.,
Cruce Alex,
Chen Weimin M.,
Simon Daniel T.,
Berggren Magnus,
Zozoulenko Igor V.
Publication year - 2017
Publication title -
advanced electronic materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.25
H-Index - 56
ISSN - 2199-160X
DOI - 10.1002/aelm.201700096
Subject(s) - absorption spectroscopy , materials science , density functional theory , cyclic voltammetry , absorption (acoustics) , polypyrrole , doping , band gap , fermi level , charge carrier , electron paramagnetic resonance , conductive polymer , polymerization , chemical physics , photochemistry , polymer , electron , chemistry , electrochemistry , nuclear magnetic resonance , computational chemistry , electrode , optoelectronics , physics , quantum mechanics , composite material
A recently developed water‐soluble self‐doped sodium salt of bis[3,4‐ethylenedioxythiophene]3thiophene butyric acid (ETE‐S) is electropolymerized and characterized by means of spectroelectrochemistry, electron paramagnetic resonance spectroscopy, and cyclic voltammetry, combined with the density functional theory (DFT) and time‐dependent DFT calculations. The focus of the studies is to underline the nature of the charge carriers when the electrochemically polymerized ETE‐S films undergo a reversible transition from reduced to electrically conductive oxidized states. Spectroelectrochemistry shows clear distinctions between absorption features from reduced and charged species. In the reduced state, the absorption spectrum of ETE‐S electropolymerized film shows a peak that is attributed to HOMO→LUMO transition. As the oxidation level increases, this peak diminishes and the absorption of the film is dominated by spinless bipolaronic states with some admixture of polaronic states possessing a magnetic momentum. For fully oxidized samples, the bipolaronic states fully dominate, and the features in the absorption spectra are related to the drastic changes of the band structure, exhibiting a strong decrease of the band gap when a polymeric film undergoes oxidation.