Charge-carrier transport in the columnar phase of the discotic liquid crystal, hexapentyloxytriphenylene, has been investigated by the time-of-flight technique over a range of temperatures and electric fields. The hole mobility was found to be temperature and electric-field-dependent with a maximum value of $2\times {10}^{-3}{\mathrm{cm}}^2∕\mathrm{V}\mathrm{s}$. Its temperature dependence is consistent with a $T^{-n}$ power law, with the factor $n$ being dependent on the electric field. The drift velocity is a linear function of the electric field below ${10}^{-5}\mathrm{V}∕\mathrm{cm}$ and tends to saturate at higher fields. These results were interpreted in the framework of correlated polaron motion as described by the nonadiabatic low-temperature limit of Holstein’s polaron theory developed for a one-dimensional diatomic chain.

• Received 10 February 2005

DOI:https://doi.org/10.1103/PhysRevB.73.064201