Area-Controllable Stamping of Semicrystalline Copolymer Ionogels for Solid-State Electrolyte-Gated Transistors and Light-Emitting Devices

Abstract

Two types of thin-film electrochemical devices (electrolyte-gated transistors and electrochemical light-emitting cells) are demonstrated using area-controllable ionogel patches generated by transfer-stamping. For the successful transfer of ionogel patches on various target substrates, thermoreversible gelation by phase-separated polymer crystals within the ionogel is essential because it allows the gel to form a conformal contact with the acceptor substrate, thereby lowering the overall Gibbs energy of the system upon transfer of the ionogel. This crystallization-mediated stamping provides a much more efficient deposition route for producing thin films of ionically conductive high-capacitance solid ionogel electrolytes. The lateral dimensions of the transferred ionogels range from 1 mm × 1 mm to 40 mm × 40 mm. These ionogel patches are incorporated in organic p-type and inorganic n-type thin-film transistors and electrochemical light-emitting devices. The resulting transistors show sub-1 V device operation with high transconductance currents, and the optoelectronic devices emit orange light through a series of electrochemical redox reactions. These results demonstrate a simple yet versatile route to employ physical ionogels for various solid-state electrochemical device applications.

Nanodroplet-Embedded Semiconducting Polymer Layers for Electrochemically Stable and High-Conductance Organic Electrolyte-Gated Transistors

“…[TFSI] ion gel dielectric. 20,23 We measured the transfer curve in the saturation regime at an applied voltage of V DS = −1 V and a sweep rate of 50 mV/s. We extracted the hole mobility (μ sat ) from the slope of the I DS versus V G plot in the saturation regime.…”

“…This value yields an average hole mobility of 1.13 (±0.56) cm 2 V −1 s −1 for pure P3HT, which is comparable to previously reported values for P3HT OEGTs. 20,23 The electrical parameters of the OEGTs are summarized in Table 1.…”

“…The solution was stirred at 70 °C for 1 h, as reported elsewhere. 20,23 The ion gel solution was spun onto a separate glass substrate and dried at room temperature to form a freestanding film. The ion gel film was cut into pieces with a razor blade and then carefully transferred onto the transistor channel using tweezers.…”

“…The combination of 1ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]) and poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) is a notable example of a solid-state ion gel electrolyte. 20 In the past several years, many research groups have varied the ion gel components in OEGTs to enhance the mechanical integrity 9,10,21,22 and simplify the filmprocessing strategies. 23,24 Despite the many promising properties of ionic electrolytes, there are common drawbacks in the electrolyte gating process.…”

“…Especially, solid-state ion gels are in principle practical for high-performance organic transistors. The combination of 1-ethyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imide ([EMIM]­[TFSI]) and poly­(vinylidene fluoride-hexafluoropropylene) (P­(VDF-HFP)) is a notable example of a solid-state ion gel electrolyte . In the past several years, many research groups have varied the ion gel components in OEGTs to enhance the mechanical integrity ,,, and simplify the film-processing strategies. , …”