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.