Structurally tailored thiophene-based hybrid materials for thin-film and single-crystal transistors: Synthesis, photophysics and carrier-transport properties

The structures, optical properties, thin-film and single-crystal field-effect transistor performance of three thiophene-based hybrid materials, 5-(9-butyl-3-carbazolyl)terthiophene (BCTT), 2,5-bis(9-butyl-3-carbazolyl)thiophene (BBCT) and 2-(9-butyl-3-carbazolyl)-5-(2-dibenzothienyl)thiophene (BCDT), are reported. The structural modifications at one side of thiophene have significant effects on the intermolecular interaction, morphology and carrier-transport properties. The adjacent molecules in the solid state of BCTT adopt H aggregation, while compounds BBCT and BCDT both exhibit the formation of J aggregation. In BCTT, the crystal structure features a herringbone motif. The hole mobility for the single-crystal field-effect transistor based on BCTT reaches 0.094 cm2 V−1 s−1, which is much higher than those of BBCT and BCDT. This study reveals that the enhanced rigidity in the molecules of BBCT and BCDT is not favorable to carrier transport.