An in-plane anisotropic organic semiconductor based upon poly(3-hexyl thiophene)

The structure and field effect mobility of a bilayer film of friction-transferred polytetrafluoroethylene (PTFE) and regioregular poly(3-hexyl thiophene) (P3HT) on a silicon dioxide substrate was studied. Friction transferred PTFE exhibits a high density of ridges and grooves on the 10-nm scale running along the friction transfer direction. Solvent cast P3HT deposits with a significant tendency for the polymer chain axis to align along the PTFE friction transfer direction. In addition, the P3HT component covers most of the surface, but leaves some high PTFE ridges exposed. The field effect mobility was highly anisotropic, with the larger mobility along the PTFE friction transfer direction. Intrinsic as well as topological causes for this anisotropy are considered.