Stable Polythiophene for Field Effect Transistors

Significance

A novel polythiophene (7) containing benzo[1,2-b:4,5-b′]dithiophene units was prepared via a ferric chloride-mediated oxidative coupling polymerization of monomer 6, which was prepared straightforwardly from dione 1 in five steps with moderate yields. Spin-coating of a solution of this polymer could produce a highly organized thin film with a close π-π stacking structure, which was characterized by AFM and X-ray diffraction studies. Field effect transistors (FET) that were fabricated on such a solution-processed thin film demonstrated a mobility of 0.15-0.25 cm² V^-1 s^-1 and a current on-off ratio of 10⁵-10⁶, even without additional thermal annealing. Devices from this polymer also showed higher stability than those based on a regioregular poly(3-hexyl­thiophene).