Anomalous high carrier mobility in smectic E phase of a 2-phenylnaphthalene derivative

Ambipolar carrier transport properties in different phases of a liquid-crystalline photoconductor, 2-(4-octylphenyl)-6-n-butoxynaphthalene were investigated by a time-of-flight technique. Carrier mobilities were increased stepwise when phase transition took place as the temperature decreased. The smectic E phase in the range of 55-125 degrees C exhibited nondispersive ambipolar carrier transport with an anomalous high carrier mobility of 1.0 x 10(-2) cm(2)/V s, while the smectic A phase between 125 and 129 degrees C had similar carrier transport with a smaller mobility of 4 x 10(-4) cm(2)/V s. In contrast to the crystalline phase, structural defects in the smectic E phase, which were obvious under microscopic observation with polarized illumination, did not deteriorate the carrier transport properties. (C) 1998 American Institute of Physics. [S0003-6951(98)02951-9].