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 °C exhibited nondispersive ambipolar carrier transport with an anomalous high carrier mobility of ${\text{1.0×10}}^{\text{−2}}\hspace{0.5em}{\mathrm{cm}}^{\mathrm{2}}/\mathrm{V s},$ while the smectic A phase between 125 and 129 °C had similar carrier transport with a smaller mobility of ${\text{4×10}}^{\text{−4}}\hspace{0.5em}{\mathrm{cm}}^{\mathrm{2}}\mathrm{/V s}.$ 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.