Comparison of polycarbazole obtained by oxidation of carbazole either in solution or in thin film form

Abstract

A comparative characterization of polycarbazole obtained either by electrochemical oxidation of carbazole in solution or vacuum evaporated carbazole films is described. The first method starts with conducting electrodes in an electrolyte solution containing the carbazole monomer. In the second, the oligomer source consists of thin films deposited under vacuum on conducting SnO 2 coated glass substrate. The polymerization is corroborated by the red shift in the threshold absorption edge and the appearance of features in the visible-to-near ultraviolet (UV) domain. After oxidation, thin films obtained by the second method are amorphous while some crystallites with carbazole structure are present in the other. The electrical conductivity and the spin density of the polycarbazole obtained by oxidation of predeposited thin films are higher and thermogravimetric measurements show that it is more stable. These results could be attributed to a longer averaged chain length in agreement with X-ray diffraction spectra which shows that probably some monomers and/or oligomers are effectively present in the polycarbazole obtained from carbazole in solution.