Spatially Uniform Thin-Film Formation of Polymeric Organic Semiconductors on Lyophobic Gate Insulator Surfaces by Self-Assisted Flow-Coating

• Published in: ACS applied materials & interfaces 2017-02, Vol.9 (7), p.6237-6245
• Main Authors: Bulgarevich, Kirill, Sakamoto, Kenji, Minari, Takeo, Yasuda, Takeshi, Miki, Kazushi
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.6b15398

Surface hydrophobization by self-assembled monolayer formation is a powerful technique for improving the performance of organic field-effect transistors (OFETs). However, organic thin-film formation on such a surface by solution processing often fails due to the repellent property of the surface against common organic solvents. Here, a scalable unidirectional coating technique that can solve this problem, named self-assisted flow-coating, is reported. Producing a specially designed lyophobic–lyophilic pattern on the lyophobic surface enables organic thin-film formation in the lyophobic surface areas by flow-coating. To demonstrate the usefulness of this technique, OFET arrays with an active layer of poly­(2,5-bis­(3-hexadecylthiophene-2-yl)­thieno­[3,2-b]­thiophene) are fabricated. The ideal transfer curves without hysteresis behavior are obtained for all OFETs. The average field-effect hole mobility in the saturation regime is 0.273 and 0.221 cm2·V–1·s–1 for the OFETs with the channels parallel and perpendicular to the flow-coating direction, respectively, and the device-to-device variation is less than 3% for each OFET set. Very small device-to-device variation is also obtained for the on-state current, threshold voltage, and subthreshold swing. These results indicate that the self-assisted flow-coating is a promising coating technique to form spatially uniform thin films of polymeric organic semiconductors on lyophobic gate insulator surfaces.