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Order–disorder transitions in poly(3,4-ethylenedioxythiophene)

journal contribution
posted on 21.01.2008, 00:00 authored by B Winther-Jensen, Maria ForsythMaria Forsyth, K West, J Andreasen, Paul Bayley, S Pas, D MacFarlane
The commonly held perception that high conductivity in conducting polymers is linked to a high level of π-stacking order in the material is shown here to be of lesser importance in highly conducting poly(3,4-ethylenedioxythiophene) (PEDT), which has been prepared by chemical vapour phase polymerisation. Despite the fact that there is a highly energetic phase transition about 130 °C (110 J/g), and that this transition corresponds to a loss of the long-range π-stacking as observed in grazing angle XRD, the conductivity remains unchanged beyond the transition and only decreases by a factor of two when heating to above 200 °C. The XRD data suggest that order in two dimension remains above the phase transition measured by DSC and this order is sufficient to maintain a high level of electronic conductivity. Furthermore, as the ligand on the iron salt used in the synthesis is varied, the conductivity of the PEDT varies over two orders of magnitude. These phenomena cannot be explained by different degree of doping or crystallinity and it is proposed that the iron salt has an ordering effect during the vapour phase polymerisation.

History

Journal

Polymer

Volume

49

Issue

2

Pagination

481 - 487

Publisher

Elsevier Ltd.

Location

Oxford, England

ISSN

0032-3861

eISSN

1873-2291

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2007, Elsevier Ltd.