A novel n-type organic semiconductor, cyano-substituted distyrylbenzene derivative, 1,4-bis{2-[4-(trifluoromethyl)phenyl]acrylonitorile}benzene, was synthesized by Knoevenagel condensation with aldehyde and acetonitrile derivatives. Fabricated thin-film transistors (TFTs) exhibited high electron field-effect mobility of 10 À2 -10 À1 cm 2 V À1 s À1 , on/off current ratio of 6 Â 10 5 . Hysteresis-free n-type transport characteristics observed in this device promises a steady operation of organic logic circuit. Almost same TFT characteristic was observed even after 1 month storage in ambient condition. The findings indicate that the material has a good resistance to atmospheric oxidants.

Field-effect mobilities and threshold voltages in organic field-effect transistors (OFETs) were studied to elucidate the difference of the OFETs performance between Si/SiO 2 and flexible polymer substrates. The polymer OFETs were built on poly(ethylene naphthalate) (PEN) film as the substrate with polyimide (PI) as the gate-insulators. Pentacene and N,N 0 -ditridecylperylene-3,4,9,10-tetracarboxylicdiimide (PTCDI-C 13 ) were employed as p-and n-type semiconductors. The n-type OFET on polymer substrates exhibited higher electron mobility and smaller threshold voltages compared with those on Si/SiO 2 . On the contrary, the p-type OFET on the Si/SiO 2 substrate showed better transport performance than that on the polymer substrate. The results are discussed taking the difference of surface potential between SiO 2 and PI gate-insulator, which possibly modifies OFET characteristics.