Polymer‐Based Organic Field‐Effect Transistors with Active Layers Aligned by Highly Hydrophobic Nanogrooved Surfaces

• Published in: Advanced functional materials 2019-11, Vol.29 (45), p.n/a
• Main Authors: Bulgarevich, Kirill, Sakamoto, Kenji, Minari, Takeo, Yasuda, Takeshi, Miki, Kazushi, Takeuchi, Masayuki
• Format: Article
• Language: English
• Subjects: Alignment; bias‐stress effects; Contact angle; Drying; Field effect transistors; Firearm accidents & safety; Hole mobility; Hydrophobicity; Materials science; nanogrooves; organic field‐effect transistors; polymeric backbone structures; polymeric organic semiconductors; Polymers; Semiconductor devices; Spin coating; Stability; Thin films; Transistors
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201905365

In this study, polymer‐based organic field‐effect transistors (OFETs) that exhibit alignment‐induced mobility enhancement, very small device‐to‐device variation, and high operational stability are successfully fabricated by a simple coating method of semiconductor solutions on highly hydrophobic nanogrooved surfaces. The highly hydrophobic nanogrooved surfaces (water contact angle >110°) are effective at inducing unidirectional alignment of polymer backbone structures with edge‐on orientation and are advantageous for realizing high operational stability because of their water‐repellent nature. The dewetting of the semiconductor solution is a critical problem in the thin film formation on highly hydrophobic surfaces. Dewetting during spin coating is suppressed by surrounding the hydrophobic regions with hydrophilic ones under appropriate designs. For the OFET array with an aligned terrace‐phase active layer of poly(2,5‐bis(3‐hexadecylthiophene‐2‐yl)thieno[3,2‐b]thiophene), the hole mobility in the saturation regime of 30 OFETs with channel current direction parallel to the nanogrooves is 0.513 ± 0.018 cm2 V−1 s−1, which is approximately double that of the OFETs without nanogrooves, and the intrinsic operational stability is comparable to the operational stability of amorphous‐silicon field‐effect transistors. In other words, alignment‐induced mobility enhancement and high operational stability are successfully achieved with very small device‐to‐device variation. This coating method should be a promising means of fabricating high‐performance OFETs. Polymer‐based organic field‐effect transistors (OFETs) with enhanced field‐effect mobility are successfully fabricated with small device‐to‐device variation using highly hydrophobic nanogrooved gate dielectric surfaces. The OFETs exhibit potential high operational stability. Spin coating of polymeric semiconductor solution onto the highly hydrophobic channel regions is enabled by appropriate patterning of hydrophobic–hydrophilic surface regions.