A1 Refereed original research article in a scientific journal
Conformational changes of a self-assembled polyalkoxythiophene during electrochemical doping: an in situ SERRS study
Authors: Kocharova N, Lukkari J, Viinikanoja A, Aaritalo T, Kankare J
Publisher: ELSEVIER SCIENCE BV
Publication year: 2003
Journal:: Journal of Molecular Structure
Journal name in source: JOURNAL OF MOLECULAR STRUCTURE
Journal acronym: J MOL STRUCT
Article number: PII S0022-2860(02)00628-2
Volume: 651
First page : 75
Last page: 83
Number of pages: 9
ISSN: 0022-2860
DOI: https://doi.org/10.1016/S0022-2860(02)00628-2
Abstract
The changes in charge carrier generation, structure, and conjugation length during the oxidative doping of a self-assembled poly-3-(3'-thienyloxy)-1-propanesulfonate (P3TOPS) monolayer on a gold surface modified by 2-mercaptoethylamine (MEA) were studied by electrochemical in situ Surface Enhanced Resonance Raman spectroscopy (SERRS) using laser excitation at 1064 nm. The oxidative doping of P3TOPS has been carried out in the potential range from - 0.3 to +0.7 V vs Ag/AgCl. The potential dependence of the integrated normalized SERRS intensities of the inter-ring vibrations exhibits a bell-shaped curve with a maximum at 0 V. The highest effective conjugation was observed between - 0.1 to + 0.1 V. During the oxidation polaronic charge carriers appear first, followed by the generation of bipolarons at higher oxidation levels. Our results imply that the highest expected p-conductivity of P3TOPS might be a result of joint action of polarons and bipolarons. The alkoxy side chain experiences trans-gauche conformational changes at potentials above 0 V, resulting in the orientation more normal to the surface. Distortions in the CSC bonds with further deplanarization of the thiophene rings were observed at potentials positive of +0.3 V. (C) 2003 Elsevier Science B.V. All rights reserved.
The changes in charge carrier generation, structure, and conjugation length during the oxidative doping of a self-assembled poly-3-(3'-thienyloxy)-1-propanesulfonate (P3TOPS) monolayer on a gold surface modified by 2-mercaptoethylamine (MEA) were studied by electrochemical in situ Surface Enhanced Resonance Raman spectroscopy (SERRS) using laser excitation at 1064 nm. The oxidative doping of P3TOPS has been carried out in the potential range from - 0.3 to +0.7 V vs Ag/AgCl. The potential dependence of the integrated normalized SERRS intensities of the inter-ring vibrations exhibits a bell-shaped curve with a maximum at 0 V. The highest effective conjugation was observed between - 0.1 to + 0.1 V. During the oxidation polaronic charge carriers appear first, followed by the generation of bipolarons at higher oxidation levels. Our results imply that the highest expected p-conductivity of P3TOPS might be a result of joint action of polarons and bipolarons. The alkoxy side chain experiences trans-gauche conformational changes at potentials above 0 V, resulting in the orientation more normal to the surface. Distortions in the CSC bonds with further deplanarization of the thiophene rings were observed at potentials positive of +0.3 V. (C) 2003 Elsevier Science B.V. All rights reserved.
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