Diketopyrrolopyrrole-thiophene-based acceptor-donor-acceptor conjugated materials for high-performance field-effect transistors.

We report the synthesis, morphology, and field-effect-transistor (FET) characteristics of new acceptor-donor-acceptor conjugated materials that consist of diketopyrrolopyrrole (DPP) acceptor groups and one of four different thiophene moieties, that is, dithiophene (2T), thieno[3,2-b]-thiophene (TT), dithieno[3,2-b:2',3'-d]-thiophene (DTT), and 5,5'''-di-(2-ethylhexyl)-[2,3';5',2'';4'',2''']quaterthiophene (4T). The optical band gaps of the as-prepared materials are smaller than 1.7 eV, which is attributed to the strong intramolecular charge transfer and the backbone coplanarity of the thiophene moieties. The order of both crystallinity and FET mobility (×10(-2)-×10(-4) cm(2) V(-1) s(-1)) is >>>DTT2DP, which differ in the structure of the π-conjugated cores and core symmetry. Well-ordered intermolecular chain packing was confirmed by the GIXD and AFM results. In particular, the FET hole mobility of was further improved to 0.1 cm(2) V(-1) s(-1), which was attributed to the well-interconnected structure through solution-shearing. These experimental results suggest the potential applications of the new DPP-thiophene-DPP conjugated materials for organic electronic devices.