Availability of liquid crystalline molecules for polycrystalline organic semiconductor thin films

We have characterized the crystallographic features and charge carrier transport properties of polycrystalline films of both triphenylene and terthiophene derivatives, which are representative materials of discotic (disc-like) and calamitic (rod-like) liquid crystals, respectively. Because of the enhanced anisotropy with the hydrocarbon chains in their molecular structure and the pre-ordered molecular alignment in the mesophase, polycrystalline films of liquid crystals, which exhibit a particular texture indicating that the molecular alignment in the liquid-crystalline phase is well preserved, suppresses the formation of grain boundaries across conduction channels and exhibit clear hole transport even in several-mu m-thick films. The present results indicate that liquid-crystalline molecules are good candidates for preparing quality organic polycrystalline semiconductor thin films for optoelectronic applications.