Comparison of charge carrier mobility between homeotropic and planar alignments in a perylene-derivative columnar liquid crystal

A new perylene-derivative exhibiting a room temperature columnar liquid crystalline phase has been characterized from the viewpoint of the mobility of charge carriers in the directions parallel and perpendicular to the columns axis, corresponding to homeotropic and planar alignments respectively. The time of flight (TOF) transients for holes were recorded at ambient temperature and over a range of electric fields (8 × 10³-1.2 × 10⁵ V/cm). The measured hole mobility is in the order of 10^-4 cm²V^-1s^-1 for planar alignment. The mobility value is up to 10 times higher in the case of homeotropic alignment which is an indication of a better electrical conductivity in the direction parallel to columns compared to the perpendicular direction. This one-dimensional semiconducting property makes CLCs interesting for semiconductor devices.