Ink‐Jet Printable, Self‐Assembled, and Chemically Crosslinked Ion‐Gel as Electrolyte for Thin Film, Printable Transistors

Abstract

voltages for operation [1][2][3][4][5][6][7] and remarkable progress has been made in the development of semiconducting channel materials [8][9][10][11] and gate insulators. [12][13][14] The EGTs are switched on/off by applying a gate potential, which leads to a migration and local redistribution of ions at the semiconductor/electrolyte interfaces. The formed electric double layer (EDL) generates high charge accumulation in the adjacent semiconducting channel, which, for instance, renders the channel conductive at a certain gate potential. For this reason, it is important for gate insulators to show high ionic conductivities, in order to quickly develop strong EDLs that improve the EGT performance. However, the switching speed of EGTs, which is slower than that for dielectric gating, is still considered as a technical hurdle for practical applications. Therefore, various types of advanced polymer electrolytes have been intensively studied.A different approach has been established in the last few years, where an ion-gel, consisting of an ionic liquid and a poly mer, is used as a gate insulator in EGTs. [14][15][16] This approach makes use of the intrinsic properties of ionic liquids, such as high ionic conductivities, negligible volatility, and Electrolyte-gated transistors (EGTs) represent an interesting alternative to conventional dielectric-gating to reduce the required high supply voltage for printed electronic applications. Here, a type of ink-jet printable ion-gel is introduced and optimized to fabricate a chemically crosslinked ion-gel by selfassembled gelation, without additional crosslinking processes, e.g., UV-curing. For the self-assembled gelation, poly(vinyl alcohol) and poly(ethylene-altmaleic anhydride) are used as the polymer backbone and chemical crosslinker, respectively, and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][OTf ]) is utilized as an ionic species to ensure ionic conductivity. The as-synthesized ion-gel exhibits an ionic conductivity of ≈5 mS cm −1 and an effective capacitance of 5.4 µF cm −2 at 1 Hz. The ion-gel is successfully employed in EGTs with an indium oxide (In 2 O 3 ) channel, which shows on/offratios of up to 1.3 × 10 6 and a subthreshold swing of 80.62 mV dec −1 .

Functional Ion Gels: Versatile Electrolyte Platforms for Electrochemical Applications

“…The molecular design of copolymer gelators offers a chance to prepare ion gels with desirable properties and functions. Depending on the cross-linking protocol, ion gels can be classified into two types: (1) physically cross-linked gels, − where the internal three-dimensional network structure is cross-linked through relatively weak and reversible molecular interactions (e.g., hydrogen bonds, hydrophobic interactions, and van der Waals forces) and (2) chemically cross-linked gels, ,− in which segments that consist of the cross-linking domains are directly linked by covalent bonds. However, the formation of chemical bonds requires additional UV or heat treatments, and relatively complex synthetic chemistry is necessary to include cross-linkable functional groups. ,, Therefore, in this section, we will mainly discuss the design principle of gelators for physically cross-linked ion gels that can be readily obtained by blending with ILs.…”

Novel Insights into Inkjet Printed Silver Nanowires Flexible Transparent Conductive Films

“…Compared to the conventional silicon processing, printable electronics offer enormous potential in their ability to enter new markets as the cost of production is decreased and new solution-processable electronic materials are developed [ 16 , 17 , 18 , 19 , 20 ]. Inkjet printing process, as a printing electronic technology, is a growing technology, which is able to deposit a desired amount of materials directly from a computer-designed image onto a designed pattern of a substrate by generating drops from a reservoir with minimal human involvement [ 9 , 13 , 14 ].…”

Electrolyte-Gated Field Effect Transistors in Biological Sensing: A Survey of Electrolytes

“…To address this, Jeong et al presented a chemically crosslinked, inkjet-printable self-assembling ion gel in EGFETs. The ion gel was composed of PVA polymer backbone, poly(ethyl methacrylate) (PEMA) chemical crosslinker, [EMIM][OTf] ionic species, and DMSO solvent [41]. The ion gel was reported to have a specific capacitance of 5.4 µF cm -2 and an ionic conductivity of 5 mS cm -1 .…”