Synthesis, characterization and field-effect transistor performance of a benzoannulated pentathienoacene derivative

Abstract

A novel benzoannulated pentathienoacene derivative dihexyl-[1]benzothieno[2′′,3′′:4′,5′]thieno[2′′,3′′:4,5;5′′,4′′:4′,5′]bisthieno[3,2-b:3′,2′-b′][1]benzothiophene was designed and synthesized. UV-vis spectra, electrochemistry and thermogravimetric analysis results reveal that this material has a large energy bandgap, low-lying highest occupied molecular orbital level and good thermal stability. Atomic force microscopy demonstrates that the thin films show high surface roughness and consisted of interconnected sheet-like crystalline grains. A highly ordered aggregation structure in grains was evidenced by X-ray diffraction measurements. Mobility up to 0.04 cm² V⁻¹ s⁻¹ and an on/off ratio over 10⁵ were achieved for the thin film field-effect transistors. These results suggest that this new benzoannulated pentathienoacene derivative is an important member of the thienoacene family and will contribute to a comprehensive analysis of the structure–property relationship of the thienoacene analogue.