Light induced damage in poly(3,4-ethylenedioxythiophene) and its derivatives studied by photoelectron spectroscopy

• Published in: Synthetic metals 2004-03, Vol.141 (1), p.67-73
• Main Authors: Marciniak, S, Crispin, X, Uvdal, K, Trzcinski, M, Birgerson, J, Groenendaal, L, Louwet, F, Salaneck, W.R
• Format: Article
• Language: English
• Subjects: 4-ethylenedioxythiophene; Applied sciences; Crosslinking and degradation; Degradation; Exact sciences and technology; Photo-oxidation; Physicochemistry of polymers; Poly; Poly(3,4-ethylenedioxythiophene); Polymers and radiations; Sulfon; TECHNOLOGY; TEKNIKVETENSKAP; X-ray photoelectron spectroscopy
• ISSN: 0379-6779; 1879-3290; 1879-3290
• DOI: 10.1016/j.synthmet.2003.08.017

Poly(3,4-ethylenedioxythiophene), usually known as PEDOT, and derivatives have attracted significant interest because of their high electrical conductivity. This electric property, however, deteriorates upon exposure to solar radiation. X-ray photoelectron spectroscopy (XPS) has been used to study the UV-light-induced chemical changes in doped PEDOT, as well as in both neutral and doped forms of its alkylated derivative—PEDOT-C 14H 29. Analysis of the XPS data indicates an oxidation of the sulfur in the thiophene ring. Apparently, photo-oxidation leads to the formation of sulfon groups, SO 2, resulting in a disruption of π-conjugation in PEDOT, which there by diminishes the conductivity of the organic layer. This hypothesis is supported by the results of a study of model molecules for pristine and the oxidized PEDOT unit: 3,4 ethylenedioxythiophene (EDOT) and 3,4 ethylenedioxythiophene and S-dioxide (EDOT-SO 2), respectively.