title: In situ ESR/UV-vis-NIR and ATR-FTIR spectroelectrochemical studies on the p-doping of copolymers of 3-methylthiophene and 3-hexylthiophene.
abstract: A combined spectroelectrochemical study by ESR/UV-vis-NIR as well as FTIR spectroscopy on the influence of the copolymer composition on the stabilization of charges upon electrochemical p-doping is presented. As compared to the parent homopolymers 3-hexylthiophene (3-HeTh) and 3-methylthiophene (3-MeTh) which seems to be irregular, FTIR studies of the copolymer of both monomers (copMeHeTh) point to a regioregular structure. The in situ ESR and UV-vis-NIR spectroelectrochemistry at higher doping levels of the polymeric materials proves bipolarons and polaron pairs as stable charged states in poly(3-hexylthiophene) as well as the copolymer copMeHeTh. During the p-doping of poly(3-methylthiophene) bipolarons are the dominating species at higher doping levels. It is demonstrated that only the simultaneous use of both the ESR and the UV-vis-NIR spectroscopy enables the differentiation of polarons (paramagnetic) and polaron pairs (diamagnetic) in a conducting polymer.
authors.affiliation: Abteilung Elektrochemie and Leitfähige Polymere, Leibniz-Institut für Festkörper- und Werkstofforschung, Helmholtzstrasse 20, D-01069 Dresden, Germany.
authors.forename: Luis F
authors.initials: LF
authors.lastname: Cházaro-Ruiz
authors.forename: Andrea
authors.initials: A
authors.lastname: Kellenberger
authors.forename: Lothar
authors.initials: L
authors.lastname: Dunsch