Propeller-shaped regioisomers of fused oligothiophenes F9Tendo, F9Tanti, and F9Texo were successfully synthesized. DFT calculations indicated that their core parts are distorted from planarity due to intramolecular steric repulsions involving large sulfur atoms. In contrast with soft crystalline F9Tanti and F9Texo, F9Tendo self-assembles into a hexagonal columnar liquid crystal (Colh LC), displaying a clear X-ray diffraction (XRD) due to its stacked π-conjugated core. In each LC column, well-organized intermolecular S-S contacts are developed triple-helically along the columnar axis with a helical pitch of 4.04 nm. Among LC semiconductors reported to date, Colh LC F9T endo displays a top-class charge-carrier mobility (0.18 cm 2 V-1 s-1) with a distinct ambipolar character featuring well-balanced hole and electron mobilities. A thin film, prepared by mixing F9Tendo with soluble fullerene PCBM, shows a photovoltaic response, when the fullerene content is large enough to compensate a small absorptivity of F9Tendo for visible light.
ASJC Scopus subject areas
- Colloid and Surface Chemistry