Thermostable Ion Gels for High-Temperature Operation of Electrolyte-Gated Transistors

Abstract

High-temperature durability is critical for application of organic materials in electronic devices that operate in harsh environments. In this work, thermostable physically cross-linked polymer electrolytes, or thermostable physical ion gels, were successfully developed using crystallization-induced phase separation of semicrystalline polyamides (PAs) in an ionic liquid (IL). In these ion gels, phase-separated PA crystals act as network junctions and enable the ion gels to maintain their mechanical integrity up to 180 °C. ILs and ion gels are suitable electrolyte candidates for thin-film devices operating at high temperatures because they outperform other electrolytes that use aqueous and organic solvents, owing to their superior thermal stability and nonvolatility. In addition to thermal stability, the PA gels exhibited high ionic conductivity (∼1 mS/cm) and specific capacitance (∼10 μF/cm2) at room temperature; these values increased significantly with increasing temperature, while the gel retained its solid-state mechanical integrity. These thermostable ion gels were successfully used as an electrolyte gate dielectric in organic thin-film transistors that operate at high temperatures (ca. 150 °C) and low voltages (<1 V). The transistors gated with the dielectrics had a high on/off current ratio of (3.04 ± 0.24) × 105 and a hole mobility of 2.83 ± 0.20 cm2/V·s. By contrast, conventional physical ion gels based on semicrystalline polymers of poly­(vinylidene fluoride-co-hexafluoropropylene) and polyvinylidene fluoride lost their mechanical integrity and dewetted from a semiconductor channel at lower temperatures. Therefore, these results demonstrate an effective method of generating thermally stable, mechanically robust, and highly conductive solid polymer electrolytes for electronic and electrochemical devices operating in a wide temperature range.

3D Printable, Highly Stretchable, Superior Stable Ionogels Based on Poly(ionic liquid) with Hyperbranched Polymers as Macro-cross-linkers for High-Performance Strain Sensors

“…Commonly, the ability of the conductive gel to tolerate a wide range of temperatures plays a vital role in it is widely applied in electronic devices. 62 Interestingly, theses ionogels also show stable mechanical strength and good stretchability under extremely low temperature at −60 °C and extreme high temperature at 250 °C (Figure 4). The above results suggest that these as-prepared single chemically cross-linked PIL ionogels has good toughness and excellent fatigue resistance, which provides an opportunity to prepare highly durable stretchable electronic devices.…”

“…Commonly, the ability of the conductive gel to tolerate a wide range of temperatures plays a vital role in it is widely applied in electronic devices . Interestingly, theses ionogels also show stable mechanical strength and good stretchability under extremely low temperature at −60 °C and extreme high temperature at 250 °C (Figure ).…”

Functional Ion Gels: Versatile Electrolyte Platforms for Electrochemical Applications

“…Triblock copolymers of polystyrene- b -poly­(methyl methacrylate) -b -polystyrene (SMS) and polystyrene- b -poly­(ethylene oxide)- b -polystyrene (SOS) are representative gelator candidates in early research stages. − In these systems, PS and PMMA/PEO serve as IL-insoluble and IL-soluble blocks, respectively, and the most widely employed examples of ILs are 1-ethyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imide ([EMI]­[TFSI]) and 1-butyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imide ([BMI]­[TFSI]). ,,− As a result of self-assembly, a physically cross-linked network structure is induced (Figure a). It is noted that the use of SMS is preferred for device applications, as the PEO block absorbs moisture in the air .…”

Tuning Threshold Voltage of Electrolyte-Gated Transistors by Binary Ion Doping

“…The electrical characteristics of the EGTs and inverters were determined using an MS-Tech probe station with a Keithley 4200 semiconductor analyzer at a voltage scan rate of 17 mV s –1 under ambient air. The charge carrier mobility (μ) was calculated by the following equation ,, μ = 0.25em L W I normalD italicep V normalD where I D is the drain current, V D is the drain voltage, e is the elementary charge, and p is the injected hole density calculated from the gate current ( I G ) vs gate voltage ( V G ) curves. The V th of the EGTs was calculated by extrapolating the linear region of transfer curve on the x -axis.…”

“…Ionic liquids (ILs) solidified with network polymers, also referred to as ionogels or ionic gels, have been actively employed in various electrochemical devices including thin-film transistors, − electrochemical light-emitting devices, , supercapacitors, − batteries, , actuators, , sensors, − gas separation, , and neuromorphic devices. , The considerable interest in ionogels originates from their superior electrochemical and mechanical properties, such as high ionic conductivity, wide electrochemical window, nonvolatility, thermal/chemical robustness, and mechanical integrity. − In addition, the aforementioned characteristics can be application-specific through the selection of network polymers, component ions (cation and anion), and their ratios. − …”