Asymmetric dithieno[3,2-b:2′,3′-d]thiophene derivatives as solution-processable small molecular organic semiconductors for organic thin film transistors

•Asymmetric dithieno[3,2-d:2′,3′-d]thiophene (DTT) derivatives were synthesized.•Substituents were added to DTT-core for solution process and enhanced performance.•Developed organic semiconductors were employed for organic field-effect transistors.•All compounds exhibited p-channel activity with mobility up to 0.07 cm2/Vs.