Improved device performance of organic crystal field-effect transistors fabricated on friction-transferred substrates.

We have improved performance of organic field-effect transistors (OFETs) composed of organic nanomolecular single crystals of a thiophene/phenylene co-oligomer. A poly(tetrafluoroethylene) thin layer was applied with friction-transfer technique to an insulator layer of silicon dioxide covering a silicon substrate. The crystals were grown in a liquid phase on the friction-transferred substrate such that the bottom-contact device was completed through depositing the crystals in firm contact with the premade metal electrodes. This technique ensures an excellent electrical contact between the crystal and the electrodes. The device shows the carrier mobility up to 0.26 cm2/Vs. The linear increase in the drain currents is clearly noted around the origin of the drain current-drain voltage action diagram. Thus we have achieved a high performance with the OFETs whose fabrication is based upon the friction-transfer technique.