Field effect transistors based on poly(3-hexylthiophene) at different length scales

Abstract

In this paper we report on thin film transistors based on drop casting solutions ofregioregular poly(3-hexylthiophene) (P3HT) over prefabricated gold electrodes. Thispolymer is known to self-organize into a lamellar structure in chloroform resulting in highfield-effect mobilities. We studied the dependency of the charge carrier mobility ofdevices prepared from solution in chloroform with electrode spacings ranging from5 µm to 20 nm. It was found that the overall trend was that the mobility decreased as theelectrode spacing was made smaller, indicating that the transport properties on closelyspaced electrodes were dominated by the contacts. Applying an ac voltage duringthe preparation of such films resulted in lower mobilities. However, P3HT inp-xylene forms fibres, which were aligned between the electrodes byapplying an ac field. Films of aligned fibres with mobilities as high as0.04 cm2 V−1 s−1 were prepared.