Synthesis and characterization of benzo[b]thieno[2,3-d]thiophene (BTT) derivatives as solution-processable organic semiconductors for organic field-effect transistors

Abstract In this study, novel benzo[b]thieno[2,3-d]thiophene (BTT) derivatives, 2-(thiophene-2-yl)benzo[b]thieno[2,3-d]thiophene (compound 1), 2-(5-(2-ethylhexyl)thiophene-2-yl)benzo[b]thieno[2,3-d]thiohpene (compound 2), and 2-(5-octylthiophene-2-yl)benzo[b]theino[2,3-d]thiohpene (compound 3), were synthesized and characterized as solution-processable organic semiconductors (OSCs) for organic field-effect transistors (OFETs). Developed organic compounds were analyzed by thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), UV–vis spectroscopy, and cyclic voltammetry for physicochemical characteristics. All BTT-derivatives were coated by solution-shearing method and fabricated films were characterized by atomic force microscopy (AFM) and θ-2θ X-ray diffraction (XRD). To investigate the electrical performance of newly synthesized BTT-derivatives, bottom-gate/top-contact OFETs were fabricated and characterized in ambient conditions. All compounds exhibited p-channel activity and especially, the resulting OFETs based on films of compound 3 showed the highest hole mobility of 0.11 cm2/Vs and current on/off ratio of 8.7 × 106.