Electronic conduction in nematic phase of small molecules

Abstract

We investigated charge-carrier transport in the nematic phase of small molecules such as 2-phenylbenzothiazoles by time-of-flight experiments, in which the conduction mechanism has been considered to be ionic. As a result, we established the hole and electron transports in the nematic phase of highly purified samples: we found that there were two transits, namely, fast and slow transits, in less pure samples; the slow transit was attributed to ionic conduction originating from trace amounts of impurities and the fast transit was attributed to electronic conduction whose attribution was elucidated by mobility changes in the diluted samples with a hydrocarbon of $n$-tetradecane $(n{\text{-C}}_{14}{\text{H}}_{30})$. From these results, we conclude that the intrinsic conduction mechanism in the nematic phase of small molecules is ambipolar and electronic, irrespective of the size of the $\ensuremath{\pi}$-conjugate system of the core moiety. Thus, they provide a new insight into the conduction mechanism in fluidic materials.