LAUSR

A new organic small molecule family comprising tetracyanoquinodimethane-substituted quinoidal dithioalky(SR)terthiophenes (DSTQs) (DSTQ-6 (1); SR = SC6H13, DSTQ-10 (2); SR = SC10H21, DSTQ-14 (3); SR = SC10H21) was synthesized and contrasted with a non-thioalkylated analogue (DRTQ-14 (4); R = C14H29). The physical, electrochemical as well as electrical properties of these new compounds are thoroughly investigated. Optimized geometries obtained from DFT calculations and single-crystal X-ray diffraction reveals the planarity of the SR-containing DSTQ core. DSTQ packs in a slipped π-π stacked 2-dimensional arrangement, with a short intermolecular stacking distance of 3.55 Å and short intermolecular S···N contacts of 3.56 Å. Thin-film morphological analysis by grazing incident X-ray diffraction (GIXRD) reveal that all DSTQ molecules are packed in an edge-on fashion on the substrate. The favorable molecular packing, the high core planarity and very low LUMO energy level (-4.2 eV) suggest that DSTQs could be electron-transporting semiconductors. Organic field-effect transistors based on solution-sheared DSTQ-14 exhibit the highest electron mobility of 0.77 cm2 V-1 s-1 with good ambient stability, which is the highest value reported to date for a such solution process terthiophene-based small molecular semiconductor. These results demonstrate that the device performance of solution-sheared DSTQs can be improved by side chain engineering.