Fabrication of high-mobility poly(3-hexylthiophene) transistors at ambient conditions

We report on the fabrication of high-mobility organic thin-film transistors (OTFTs) made and tested under ambient conditions. A bottom gate, bottom contact architecture was used with a layer of poly(3-hexylthiophene) deposited on a 50 nm thick Al2O3 dielectric with pre-patterned Au source and drain electrodes. Fluoroalkyl trichlorosilane treatment of the Al2O3 dielectric was found to significantly improve device performance. The field-effect hole mobility reproducibly reached 0.2 cm2 V−1 s−1 (best device 0.29 cm2 V−1 s−1) with an on/off ratio of 104. Electrical and synchrotron X-ray scattering characterization shows that an interaction at the FOTS/P3HT interface is responsible for the high performance of these devices. The fabrication method described here is carried out under ambient conditions and does not require any post-deposition annealing or vacuum drying steps for the organic film; therefore it can simplify the manufacturing of OTFTs.