Solution processable benzo[b]thiophene derivatives as small molecular organic semiconductors for organic field effect transistors

In this study, four new organic semiconductors based on benzo[b]thiophene derivatives were synthesized and characterized as the active layer of organic field-effect transistors (OFETs) to investigate the effect of different isomers and end-group moieties on the electrical performance. The top-contact/bottom-gate OFETs were fabricated via solution-shearing methods and exhibited p-channel activity. In particular, the thin film with a single BT moiety attached via the 6-position showed the highest mobility up to 0.055 cm²/Vs and current on/off ratio of 2.5 × 10⁷. The microstructure and surface morphology of the thin films were analyzed by X-ray diffraction (XRD) and atomic force microscopy (AFM) to investigate the factors contributing to the difference in electrical performance of the devices.