Controlled nanorubbing of polythiophene thin films for field-effect transistors

We present results obtained by applying the nanorubbing process to improve the electrical performance of regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) thin films. Essentially, we use a scanning atomic force microscope tip to induce a controlled deformation on the surface consisting of parallel grooves with a period imposed by the scanning parameters. The optical characterization of the rubbed zones highlights an orientation of P3HT chains along the scanning direction. When the nanorubbing process is orienting the polymer chains within the channel of a field-effect transistor, we observe that the charge carrier mobility increases (decreases) when the tip scans parallel (perpendicular) to the source-drain axis. This difference likely stems from the polymer chains orientation induced by the alignment process. (C) 2008 Elsevier B.V. All rights reserved.