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.
Polycarbazole has been synthesized by electrochemistry. The carbazole monomer source consists either in carbazole in solution in the electrolyte or in carbazole deposited in thin film form onto the working electrode. The two families of polymers have been studied by infrared absorption, X-ray diffraction, thermal gravimetric analysis, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy, electron spin resonance, and electrical conductivity measurements. It is shown that the polycarbazole films obtained with carbazole deposited in the thin film form exhibit a better polymerization efficiency and an electrical conductivity one order of magnitude higher. This result is in good accordance with a higher spin density and homogeneity. It is proposed that not only are some monomers activated during the evaporation but also that the physical contact between the working electrode and the continuous carbazole films induces the growth of homogenous highly polymerized polycarbazole films. In agreement with this suggestion, the SEM study shows that this type of polycarbazole thin films keep in memory the morphology of the SnO 2 under layer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.