Extrinsic carrier photogeneration in polyhyphen;Nhyphen;vinylcarbazole. III. CT fluorescence quenching by an electric field

摘要

Fieldhyphen;induced CT fluorescence quenching has been observed in a polyhyphen;Nhyphen;vinylcarbazole (PVCz) film doped with 1,2,4,5hyphen;tetracyanobenzene, which exhibits a large sensitized photocurrent in the corresponding CT absorption region. The CT fluorescence quenching is attributed to carrier photogeneration by the rsquo;rsquo;fieldhyphen;assisted thermal dissociationrsquo;rsquo; of an ion pair which has a higher excited CT state as precursor. The Onsager model for the dissociation of an ion pair satisfactorily explains the experimental data of the field and temperature dependences of the fluorescence quenching by an electric field. Combining previously proposed mechanism of extrinsic carrier photogeneration in the exciplex systems, a more general mechanism has been presented for extrinsic carrier photogeneration in solidhyphen;state, excited donorndash;acceptor systems.