Organic field-effect transistors based on π-extended dibenzotetrathiafulvalene analogues with thiophene spacers

Dibenzotetrathiafulvalene (DBTTF) analogs containing fused thiophene spacers were synthesized and characterized by cyclic voltammetry, UVvis absorption spectroscopy, quantum chemical calculations, single-crystal X-ray analysis, overlap integral calculations, field-effect transistor (FET) characteristics, X-ray diffraction, and atomic force microscopy (AFM). The single-crystal X-ray analysis revealed that the DBTTF with a thieno[3,2-b]thiophene spacer has a molecular geometry with short intramolecular S⋯S contacts and a herringbone packing structure with short intermolecular S⋯S contacts leading to large two-dimensional overlap integrals. The molecule afforded a crystalline thin film with wellordered molecular orientation corresponding to the single-crystal structure. The FET device based on this molecule exhibited good mobility of 0.29 cm ²V^-1 s^-1 and low threshold voltage of -0.3V. The effects of the thiophene spacer on the properties, structure, and FET performances were investigated here.