J‐Type Self‐Assembled Supramolecular Polymers for High‐Performance and Fast‐Response n‐Type Organic Electrochemical Transistors

Abstract

To date, high-performance organic electrochemical transistors (OECTs) are almost all based on conjugated polymers. Small molecules can be synthesized with high purity without batch-to-batch variations. However, small molecules require highly crystalline films and good molecular packings to achieve high charge carrier mobilities. Such features make their films unsuitable for ion diffusion or make their molecular packing distorted due to ion diffusion, resulting in poor ion/charge carrier transport properties and slow response speed. Herein, it is proposed to construct small-molecule-based supramolecular polymers to address these issues. A molecule, namely TDPP-RD-G7 is designed, which exhibits J-type self-assembling behaviors and can form supramolecular polymers in solution and conjugated-polymer-like networks in solid state. More importantly, the porous supramolecular polymer networks allow fast ion diffusion and greatly increase the device response speeds. As a result, the TDPP-RD-G7 exhibits record fast response speeds (τ on /τ off ) of 10.5/0.32 ms with high figure-of-merit (µC*) of 5.88 F cm −1 V −1 s −1 in small-molecule OECTs. This work reveals the possible reasons that hinder the response speeds in small-molecule OECTs and demonstrates a new "supramolecular polymer" approach to high-performance and fast-response small-molecule-based OECTs.

Materials design and applications of n-type and ambipolar organic electrochemical transistors

“…Recently, Lei et al reported two small molecules with the TDPP as the building block and two electron-deficient malononitrile (CN) and RD as the end functional groups. 33 TDPP-RD-G7 (Fig. 5c) was capable of forming J-type supramolecular polymers and ''polymer-like'' networks, which can enhance its charge transport and reduce its susceptibility to ion diffusion.…”

“…These advancements include the development of a no-side-chain polymer BBL, the introduction of conductive polymer PBFDO, 31 the proposal of “doped state engineering”, 14 and the use of small molecule materials. 32,33 Among these materials, PBFDO has shown impressive performance. 31 However, PBFDO possesses a hydrophobic backbone with no hydrophilic side chains and it only shows good performance in thin films (∼50 nm).…”

On the fundamentals of organic mixed ionic/electronic conductors

“…Pure p-type redox polymers bear, for example, triarylamine or carbazole redox units. 4 On the small molecules front, the films of oligoether tethered fullerenes, 5 thiophene-flanked diketopyrrolopyrrole units, 6 polycyclic systems consisting of naphthalene bis-isatin dimer core with rhodanine terminals, 7 or thiophene-EDOT based cores 8 are among the structures that can be electrochemically doped and de-doped in aqueous media, while they are yet to be commonly used by different research teams. All these systems can be modified with additives, dopants, and through processing and post-processing.…”

Low-voltage operating, high mobility top-gate structural flexible organic thin-film transistor with a one-step spin-coated binary polymer gate dielectric

“…The organic thin-film transistors (OTFTs) have attracted great attentions for their inherent advantages on the low-cost, low-temperature manufacture, solution processable, and good mechanical flexibility, and their widely application prospects in the fields of flat panel displays, integrated circuits (ICs), memories, and sensors [1][2][3][4][5]. In past two decades, tremendous efforts have been devoted to develop the OTFTs, for promoting the commercialization.…”