The bottom-gate top-contact OTFTs were fabricated on an indium tin oxide
The bottom-gate top-contact OTFTs were fabricated on an indium tin oxide (ITO) coated glass substrate that had been cleaned with detergent, acetone, and isopropyl alcohol and treated in a UV-ozone cleaner for 30 min. A solution of PNIPAM (15 wt%) in deionized water was spin-coated (2000 rpm) onto the substrate and then baked at 85 °C for 40 min. 70-nm pentacene semiconductor was thermally evaporated under a pressure of 5 ? 10–6 torr at a deposition rate of 0.3–0.5 Å s–1. After deposition of the active layer, 40-nm Au source and drain electrodes were deposited through a shadow mask having a channel width of 200 µm and a channel length of 2000 µm. For fabrication of the flexible device on the polyethylene terephthalate (PET) substrate, 15 wt% PNIPAM in water was spin-coated twice (1000 rpm each time), followed by deposition of pentacene and the Au source and drain electrodes, using the same procedures described above.