Recent progresses in organic field effect transistors based on π-conjugated organic molecules

Organic field-effect transistors (OFETs) have gained considerable interest as the key elements for realizing future ubiquitous electronics because they have a large number of advantages such as the flexibility, light-weight, and ease of design. In this article, recent material developments in this field, including phenacene-type molecules, thienoacene derivatives, and a series of donor-acceptor (D-A)-type polymers, are summarized. Phenacene-type molecules possess a low HOMO level and a wide band gap. Recently, among phenacene-type molecules, picene, [6]phenacene, and [7]phenacene have been recognized as unique molecules because using them high field-effect mobility in the transistors can be realized. In addition, in some cases the FET properties were found to be highly improved by an incorporation of alkyl chains to the parent motif and one can expect to apply these molecules to a solution-process owing to a high solubility in common organic solvents. Furthermore, recent progress of diketopyrrolopyrrole (DPP) and isoindigo (IID)-based D-A polymers showing high mobility are introduced.