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One-Step Interface Engineering for All-Inkjet-Printed, All-Organic Components in Transparent, Flexible Transistors and Inverters: Polymer Binding

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journal contribution
posted on 20.02.2017, 00:00 by Jewook Ha, Seungjun Chung, Mingyuan Pei, Kilwon Cho, Hoichang Yang, Yongtaek Hong
We report a one-step interface engineering methodology which can be used on both polymer electrodes and gate dielectric for all-inkjet-printed, flexible, transparent organic thin-film transistors (OTFTs) and inverters. Dimethyl­chlorosilane-terminated polystyrene (PS) was introduced as a surface modifier to cured poly­(4-vinylphenol) dielectric and poly­(3,4-ethylene­dioxy­thiophene):poly­styrene­sulfonate (PEDOT:PSS) electrodes without any pretreatment. On the untreated and PS interlayer-treated dielectric and electrode surfaces, 6,13-bis­(tri­isopropyl­silyl­ethynyl)­pentacene was printed to fabricate OTFTs and inverters. With the benefit of the PS interlayer, the electrical properties of the OTFTs on a flexible plastic substrate were significantly improved, as shown by a field-effect mobility (μFET) of 0.27 cm2 V–1 s–1 and an on/off current ratio (Ion/Ioff) of greater than 106. In contrast, the untreated systems showed a low μFET of less than 0.02 cm2 V–1 s–1 and Ion/Ioff ∼ 104. Additionally, the all-inkjet-printed inverters based on the PS-modified surfaces exhibited a voltage gain of 7.17 V V–1. The all-organic-based TFTs and inverters, including deformable and transparent PEDOT:PSS electrodes with a sheet resistance of 160–250 Ω sq–1, exhibited a light transmittance of higher than 70% (at wavelength of 550 nm). Specifically, there was no significant degradation in the electrical performance of the interface engineering-assisted system after 1000 bending cycles at a radius of 5 mm.