Ion‐Gating Engineering of Organic Semiconductors toward Multifunctional Devices

Abstract

Ion‐gating engineering provides a new way to bridge electronics and ionics, and more importantly, bringing unprecedented opportunities for organic semiconductors (OSCs) based bioelectronics and solid‐sate physics. Compared with conventional‐dielectric gating, ion gating shows unique features in an extremely large electric field, high transconductance, low operating frequency, and ultrahigh carrier concentration. It therefore boosts the rapid development of different organic devices, including neuromorphic devices and amplifying transducers, and offers a powerful strategy to probe the charge transport, thermoelectric and even superconducting properties of organic materials at different scales. In this review, first, the fundamental mechanism of ion gating is discussed to enable multifunctional devices. The electrolyte materials and organic semiconductors are also summarized that are widely used in ion‐gated devices and their associated properties are examined. Moreover, key concepts of manipulating ion–electron coupling are highlighted for opening up new frontiers in organic multifunctional electronics. Finally, the challenges and perspectives on the ion gating of OSCs are proposed to highlight the directions that deserve attention in this emerging interdisciplinary field.

Unveiling the Interplay among End Group, Molecular Packing, Doping Level, and Charge Transport in N‐Doped Small‐Molecule Organic Semiconductors

“…Organic thermoelectric (OTE) materials have attracted considerable attention because of their low toxicity, being light-and new n-doping processes. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] Recently, high electrical conductivity of over 90 S cm −1 has been achieved in a n-doped strong electron-deficient conjugated polymer. [28] Although the high electrical conductivity has been obtained, the PF and ZT value (76 µW m −1 K −2 and 0.06, respectively) of the doped conjugated polymer are usually low because of its low Seebeck coefficient (approximately −91 µV K −1 ), which may originate from the low charge carrier mobility and large structural and energetic disorders.…”

A Variety of Functional Devices Realized by Ionic Nanoarchitectonics, Complementing Electronics Components

“…[70,71] More recently, ionic liquids, which are free of solvents and thus have wide redox windows, were applied to EDLTs for doping extremely high-density electronic carriers in various electronic materials in order to explore novel electronic functions. [72][73][74][75][76][77][78][79][80][81][82][83] In the search for room temperature superconductivity, some interesting results have been achieved through the use of EDL carrier doping using EDLTs consisting of ionic liquids. [72][73][74][75] However, EDLs consisting of solid electrolytes, termed all-solidstate EDLT, have not been used for this purpose to date.…”

“…[ 70,71 ] More recently, ionic liquids, which are free of solvents and thus have wide redox windows, were applied to EDLTs for doping extremely high‐density electronic carriers in various electronic materials in order to explore novel electronic functions. [ 72–83 ]…”

A photo-responsive organic electrochemical transistor

“…Functional diversification in organic materials represents a major research challenge with high potential for disruptive technological applications in tomorrow's optoelectronics and nanoelectronics. [1][2][3] The motion of ionic charge carriers at a solid-liquid (or semisolid) electrolyte interface brings extraordinary functionalities to traditional organic semiconductors (OSCs), thus enabling the future development of these technologies. 4,5 Iontronics is a discipline that exploits such concepts to control the ionic-electronic transport in mixed conductors, 6 with its most promising application being device interfacing with biological tissues and living systems, i.e., bioelectronics.…”