Hole transport in liquid crystalline media. II. Hole drift mobilities of copolymers of acrylates with side-chain mesogens and dimeric carbazoles

Hole drift mobilities of films of copolymers of acrylates with side-chain mesogens and dimeric carbazoles were measured by the time-of-flight method. The copolymers were composed of acrylates with side-chain phenylbenzoate or cyanobiphenyl and acrylates with side-chain 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane (DCZB). Incorporation of the DCZB moiety into the copolymers resulted in homogeneous dispersion of the carrier molecules, but destabilization to a great extent of the liquid-crystalline phase of the resulting copolymers. The hole drift mobility was found to be enhanced in copolymer films with more ordered structure of the DCZB moieties, indicating that orientation of the active molecules is favorable for the hole transport.