Resonance Raman spectroscopic studies on the conducting state of polyvinylcarbazole and its model compounds

Abstract

The conductivity in polyvinylcarbazole (PCVz), a well known photoconducting polymer, has been attributed to the migration of the cation radicals 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. Vibrational assignments are presented for the observed frequencies by comparison with similar compounds and also by density functional theoretical calculations. The structure of the monomer and dimer radical cations 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 localized on the dimer, undergo a downshift compared to that of N-ethylcarbazole (NEC) dimer radical cation. This shift has been tentatively attributed to the interaction of the PVCz dimer radical cation with the neutral carbazole which may be facilitated by the conformational rearrangement required for the exchange of charge with neutral carbazole.