Modification of alkyl side chain on thiophene-containing benzothieno[3,2-b]benzothiophene-based organic semiconductors for organic field-effect transistors

In this study, three new organic semiconductors based on benzothieno[3,2-b]benzothiophene with double thiophene rings and different types of alkyl side chains were synthesized and characterized as active layers for organic field-effect transistors. Physicochemical properties of the newly synthesized organic compounds including thermal, optical, and electrochemical properties were characterized through thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), UV–vis spectroscopy, and cyclic voltammetry (CV). The thin film surface morphology and texture of all three compounds fabricated by solution-shearing process were analyzed via atomic force microscopy (AFM) and θ-2θ X-ray diffraction (XRD). All semiconductor thin films showed p-channel activity and the compound with monoalkylated 2-ethylhexyl group as a substituent exhibited the highest electrical performance with carrier mobility of 0.033 cm2/Vs and current on/off ratio of ∼106. •[1]benzothieno[3,2-b]benzothiophene (BTBT)-based organic semiconductors were synthesized.•The effect of different side chains on BTBT-based semiconductors was investigated.•Developed compounds were employed as active layer for organic field-effect transistors.•Monoalkylated BTBT compound showed the highest electrical performance.