1,2,5,6-Tetrathiocin as a scaffold for improved charge transport in double-cable oligothiophene systems

Four novel small molecules featuring central 1,2,5,6-tetrathiocin (TTC) units fusing two oligothiophene chains have been prepared, characterised and their structures elucidated through X-ray crystallography. These compounds have been evaluated as p-channel semiconductors in organic field-effect transistor devices, representing the first time that any tetrathiocin-containing compound has been utilised in organic transistors. Through extensive optimisation, involving the screening of different processing solvents, surface treatments, post-processing conditions, dielectric materials, and device configurations, hole mobilities (µh) in the 10-2 cm2 V-1 s-1 range were obtained for the most optimised devices, with the highest value of 7.3 × 10-2 cm2 V-1 s-1 achieved in 5T-TTC. The double-cable design, established through two parallel oligothiophene chains in the same molecule bridged by a tetrathiocin core, provides improved device characteristics over analogous double-cable oligothiophenes with tetrathiafulvalene and germanium cores.