Benzothieno[2,3-b]thiophene semiconductors: synthesis, characterization and applications in organic field-effect transistors

An efficient synthetic approach to a series of benzothieno[2,3-b]thiophene (BTT) derivatives used as an important core with different bridge spacers is described. Thermal properties of the present compounds are stable: neither phase transition nor thermal decomposition was observed up to 300 °C. The adjacent molecule crystal stackings are shifted affording a nearly 1/3 intermolecular π-overlap. The OFETs based on BTTB exhibit excellent field-effect performances with a mobility of 0.46 cm2 V−1 s−1 and on–off current ratios larger than 107 at room temperature. All the results demonstrate these benzothieno[2,3-b]thiophene derivatives as promising materials for optoelectronic devices.