New dithieno[3,2-b:2′,3′-d]thiophene oligomers as promising materials for organic field-effect transistor applications

We designed and synthesized new organic semiconductors for organic field-effect transistor (OFET) using the fused thiophene derivative, dithieno[3,2-b:2',3'-d]thiophene (DTT), as a core of the molecules. In order to understand the influence of dithienothiophene unit on the chemical, physical and electronic properties of the final oligomer we synthesized a related molecule having a fluorene unit as the core, which is known to display different chemical and electronic characteristics. The target co-oligomers based on dithienothiophene and thiophene or fluorene derivatives have been obtained by Suzuki coupling reactions. Electrochemical characterization of these molecules as films evidenced their reversible oxidation, a necessary condition for OFET active material. Their electronic energy scheme is well matched to the high work-function electrodes, gold or platinum. A closely packed face-to-face or face-on stacking arrangements in cast films and highly ordered vacuum-evaporated films are expected in view of the structural packing observed in similar compounds. (C) 2004 Elsevier B.V. All rights reserved.