Light-emitting alternating copolymers and their intramolecular charge transfer state†

Two light-emitting conjugated polymers alternatively involving arylenevinylene and a N-alkyl carbazole moieties in the main chain were investigated. The formation of an intramolecular charge transfer state was probed within the repetition units of the copolymers. A tail absorption band and dual fluorescence were found for one of the copolymers, poly[(9-(2-ethyl-hexyl)-9H-carbazol-3,6-ylene)-alt-(anthracen-9,10-ylene) vinylene], Cz-PAV. Solvent polarity effects were studied by means of steady-state spectroscopy and fluorescence-lifetime measurements. Fluorescence emission spectra at 77 K were also explored. All the results show that a photoinduced intramolecular charge transfer state was formed in Cz-PAV. The formation of this state may be related to the electron affinity of the acceptor group contained in the copolymer and to the molecular conformation of the copolymer. Copyright © 2003 John Wiley & Sons, Ltd.