RESONANCE RAMAN-SPECTROSCOPIC STUDIES ON THE CONDUCTING STATE OF POLYVINYLCARBAZOLE AND ITS MODEL COMPOUNDS

The conductivity in polyvinylcarbazole (PCVz), a well known photocondu cting polymer, has been attributed to the migration of the cation radi cals along the chain. In this paper, chemically generated monomer and dimer radical cations of the carbazolyl group and the conducting form of PVCz have been investigated by resonance Raman (RR) spectroscopy. V ibrational assignments are presented for the observed frequencies by c omparison with similar compounds and also by density functional theore tical calculations. The structure of the monomer and dimer radical cat ions have been inferred from the RR spectra. It has been observed that Raman bands of the radical cation of PVCz in which the charge is loca lized on the dimer, undergo a downshift compared to that of N-ethylcar bazole (NEC) dimer radical cation. This shift has been tentatively att ributed to the interaction of the PVCz dimer radical cation with the n eutral carbazole which may be facilitated by the conformational rearra ngement required for the exchange of charge with neutral carbazole. (C ) 1998 John Wiley & Sons, Ltd.