Charge Transport Anisotropy in n-Type Disk-Shaped Triphenylene-Tris(aroyleneimidazole)s

Two novel n-type disk-shaped molecules containing a triphenylene core and three fused naphthaleneimide imidazole or peryleneimide imidazole ``arms'' are synthesized and characterized. Their optical and electronic properties are consistent with the pi-extended structural feature of the aromatic cores. The n-type charge carrier mobilities of these molecules are evaluated by both field effect transistors and space-charge limited-current measurements, which show drastically different mobility anisotropy. A strong correlation between film morphology and the charge transport behavior is established by X-ray scattering and atomic force microscopic analyses.