Synthesis and studies on 2-hexylbithiophene end-capped oligomer for OTFT

The new organic semiconductor which is composed of divinylbenzene core unit and hexylbithiophene on both sides, 1,4-bis-(1′-(2″-hexyl-5″-[2,2′]bithienyl)ethenyl)benzene, was synthesized by Wittig reaction. The structure of obtained material was confirmed by NMR, FT-IR and mass, and the physical properties were characterized by UV-visible spectroscopy, cyclovoltammetry, differential scanning calorimetry, and thermogravimetric analysis. Vacuum-evaporated film was characterized by X-ray diffraction and atomic force microscopy (AFM). It forms highly ordered polycrystalline vacuum-evaporated film. It exhibits field-effect performances, with a hole mobility of 0.066 cm2/V and on/off ratio up to 4.61 × 105, and a subthreshold slope of 0.44 V when it was deposited at Ts = 90 °C on OTS-treated SiO2.