Relation between supramolecular order and charge carrier mobility of branched alkyl hexa-peri-hexabenzocoronenes

The control of the solubility and thermal behavior of discotic materials requires a variation of the substituents. In this study, it has been shown that long alkyl side chains branched at the very close vicinity of a hexa-peri-hexabenzocoronene (HBC) aromatic core results in the decrease of the pi interaction between single disks and thus in a significant lowering of the isotropization temperature but maintains a high degree of intracolumnar order at room temperature, which is usually the operating temperature in electronic devices. The pronounced molecular packing yielded one of the highest charge carrier mobilities obtained for a noncrystalline discotic compound giving these materials importance as attractive organic semiconductors for organic electronics. This stands in strong contrast to the behavior of other large discotic molecules substituted by bulky alkyl side chains; they generally lead to an increase of the intracolumnar disorder which is a disadvantage for the one-dimensional charge carrier transport.