Electronic transport in discotic liquid crystal columns

Conduction along discotic molecular columns was originally assumed to be due to hopping transport. However, hole mobilities of the order of 1 cm/sup 2/V/sup -1/s/sup -1/ have been reported for columns formed from two complementary triphenylene species, which results in a higher degree of ordering than obtained from each single species alone. The mobility values for the highly ordered discotic columns also show a very weak temperature dependence. Both these points argue against a hopping transport mechanism. In this work we investigate the possibility of band transport in discotic molecular columns, by using a Monte Carlo simulation of hole transport in a 1-dimensional periodic array. The effect of different types of defects ncluding vacancies and dislocations - is investigated to determine the likely extent of disorder in the material based on the measured mobilities. A stochastic distribution of coherence lengths is used. Phonon scattering is also included, due to out-of-plane vibrations of the carbon-hydrogen bonds on the aromatic core, but is found to have a relatively small effect on the overall mobility.