title: Transfer printing of thermoreversible ion gels for flexible electronics.
abstract: Thermally assisted transfer printing was employed to pattern thin films of high capacitance ion gels on polyimide, poly(ethylene terephthalate), and SiO2 substrates. The ion gels consisted of 20 wt % block copolymer poly(styrene-b-ethylene oxide-b-styrene and 80 wt % ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)amide. Patterning resolution was on the order of 10 μm. Importantly, ion gels containing the block polymer with short PS end blocks (3.4 kg/mol) could be transfer-printed because of thermoreversible gelation that enabled intimate gel-substrate contact at 100 °C, while gels with long PS blocks (11 kg/mol) were not printable at the same temperature due to poor wetting contact between the gel and substrates. By using printed ion gels as high-capacitance gate insulators, electrolyte-gated thin-film transistors were fabricated that operated at low voltages (<1 V) with high on/off current ratios (∼10(5)). Statistical analysis of carrier mobility, turn-on voltage, and on/off ratio for an array of printed transistors demonstrated the excellent reproducibility of the printing technique. The results show that transfer printing is an attractive route to pattern high-capacitance ion gels for flexible thin-film devices.
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota , 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Keun Hyung
authors.initials: KH
authors.lastname: Lee
authors.forename: Sipei
authors.initials: S
authors.lastname: Zhang
authors.forename: Yuanyan
authors.initials: Y
authors.lastname: Gu
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Lodge
authors.forename: C Daniel
authors.initials: CD
authors.lastname: Frisbie
mesh_terms: D004581:Electronics; D005782:Gels / Q000737:chemistry*; D007477:Ions / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D011093:Polyethylene Terephthalates; D011108:Polymers / Q000737:chemistry; D012666:Semiconductors; D012822:Silicon Dioxide / Q000737:chemistry*; D013696:Temperature; D014173:Transistors, Electronic
chemical_list: D005782:Gels; D007477:Ions; D011093:Polyethylene Terephthalates; D011108:Polymers; D011092:Polyethylene Glycols; D012822:Silicon Dioxide