XPS and ESR studies of electrochemically synthesized polycarbazole post-doped with iodine
✍ Scribed by J. C. Bernede; H. Taoudi; A. Bonnet; P. Molinie; M. Morsli; M. A. De Valle; F. Diaz
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 197 KB
- Volume
- 71
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
Polycarbazole powders obtained by electrochemical oxidation of carbazole thin films or of carbazole in solution in the electrolyte have been post-doped with iodine and characterized by room temperature electrical conductivity, X-ray photoelectron spectroscopy (XPS), and electron spin resonance (ESR). Similar results are obtained with polymers saturated with iodine at room temperature after 6 weeks and with polymers doped at 383 K for 24 h. The polymers obtained from carbazole thin films have a higher electrical conductivity ( ϳ 10 Ϫ4 ⍀ Ϫ1 cm Ϫ1 ) and a higher spin density (9.9 10 21 spins mol Ϫ1 g Ϫ1 ), which corresponds to 71 atom % of ionic iodine. The polymer radicals are located on the nitrogen, and the percentage of N ϩ is 40 atom %. The electrical conductivity of the polymers obtained from carbazole in solution in the electrolyte is two order of magnitude smaller. The percentage of N ϩ is only 25 atom % with an ionic iodine percentage of 13 atom %. So, the most important parameter is not the iodine percentage introduced after doping into the polymers but the percentage of ionic iodine present in the polymers. The differences that are put in evidence can be explained by a better polymerization efficiency of the carbazole when it is deposited on thin film form by vacuum evaporation before electrochemical oxydation.