High ambipolar carrier mobility in self-organizing terthiophene derivative

Dialkylterthiphene derivatives exhibiting self-organization of molecular alignment were synthesized and their electrical properties were studied. It was found that these materials exhibited very fast electron transport in smectic mesophases as well as hole transport, both of which were independent of electric field and temperature. The mobility for electrons and holes was ${\text{5×10}}^{\text{−4}}\hspace{0.5em}{\mathrm{cm}}^{\mathrm{2}}\mathrm{/V s}$ in smectic C (SmC) and was increased up to ${\text{2×10}}^{\text{−3}}\hspace{0.5em}{\mathrm{cm}}^{\mathrm{2}}\mathrm{/V s}$ and even more up to ${\text{1×10}}^{\text{−2}}\hspace{0.5em}{\mathrm{cm}}^{\mathrm{2}}\mathrm{/V s}$ in accompany with upgrade of molecular alignment from SmC to SmF and from SmF to SmG, respectively. This abrupt increase in the mobility to the extent of about one order of magnitude corresponds to that in 2-phenylnaphthalene derivatives at the phase transition from SmA to SmB and from SmB to SmE whose molecular alignments are in good correlation with those of SmC, SmF, and SmG, respectively.