Carrier transport in calamitic mesophases of liquid crystalline photoconductor 2-phenylnaphthalene derivatives

We have characterized carrier transport in mesophases of 2-phenyl-naphthale ne derivatives by transient photocurrent measurements. In contrast to ionic conduction of isotropic and nematic (N) phase, electronic and ambipolar ca rrier transport was observed in smectic A (SmA), smectic B (SmB), and smect ic E (SmE) phases. In particular, anomalous large mobilities on the order o f 10(-2)cm(2)/Vs were obtained in SmE phase. Carrier mobilities in mesophas es of 2-phenynaphthalene derivatives were increased stepwise corresponding to sophistication of molecular ordering from N to SmE. This indicated a dom inant effect of molecular ordering on the carrier transport of calamitic me sophases.