Photoconductive anisotropy in smectic liquid crystalline photoconductor, 2-(4′-octylphenyl)-6-dodecyloxynaphthalene

Photoconductive anisotropy of a liquid crystalline photoconductor, 2-(4'-octylphenyl)-6-dodecyloxynaphthale (8-PNP-O12) exhibiting smectic B (SmB) and smectic A (SmA) phases, was studied by steady-state and transient photocurrent measurements for homogeneous and homeotropic alignment cells. In the steady-state photocurrent measurement under UV light illumination, the photoconductive anisotropic ratio, i.e., a photocurrent ratio for the homogeneous cell to the homeotropic one, was 10 in the SmB phase and 5 in the SmA phase, in contrast to no difference in the isotropic phase. In the transient photocurrent measurements, very small photocurrents at a detection limit were observed in the homeotropic cells irrespective of the mesophases, while rapid nondispersive transient photocurrents were obtained in the homogeneous cells.