Over 60 h of Stable Water‐Operation for N‐Type Organic Electrochemical Transistors with Fast Response and Ambipolarity

• Published in: Advanced science Vol. 11; no. 29; pp. e2400872 - n/a
• Main Authors: Pan, Tao, Jiang, Xinnian, Doremaele, Eveline R. W., Li, Junyu, Pol, Tom P. A., Yan, Chenshuai, Ye, Gang, Liu, Jian, Hong, Wenjing, Chiechi, Ryan C., Burgt, Yoeri van, Zhang, Yanxi
• Format: Journal Article
• Language: English
• Published: Germany John Wiley & Sons, Inc 01.08.2024; John Wiley and Sons Inc; Wiley
• Subjects: ambipolar organic mixed ionic‐electronic conductors; Aqueous solutions; Copolymers; Electrolytes; organic electrochemical transistors; Polymer films; Polymers; stability; threshold voltage; Transistors; ambipolar organic mixed ionic‐electronic conductors; organic electrochemical transistors; threshold voltage; stability
• DOI: 10.1002/advs.202400872
• ISSN: 2198-3844

Organic electrochemical transistors (OECTs) are of great interest in low‐power bioelectronics and neuromorphic computing, as they utilize organic mixed ionic‐electronic conductors (OMIECs) to transduce ionic signals into electrical signals. However, the poor environmental stability of OMIEC materials significantly restricts the practical application of OECTs. Therefore, the non‐fused planar naphthalenediimide (NDI)‐dialkoxybithiazole (2Tz) copolymers are fine‐tuned through varying ethylene glycol (EG) side chain lengths from tri(ethylene glycol) to hexa(ethylene glycol) (namely P‐XO, X = 3–6) to achieve OECTs with high‐stability and low threshold voltage. As a result, the NDI‐2Tz copolymers exhibit ambipolarity, rapid response (<10 ms), and ultra‐high n‐type stability. Notably, the P‐6O copolymers display a threshold voltage as low as 0.27 V. They can operate in n‐type mode in an aqueous solution for over 60 h, maintaining an on‐off ratio of over 105. This work sheds light on the design of exceptional n‐type/ambipolar materials for OECTs. It demonstrates the potential of incorporating these ambipolar polymers into water‐operational integrated circuits for long‐term biosensing systems and energy‐efficient brain‐inspired computing. Four NDI‐2Tz copolymers (P‐XO, X = 3–6) with modified EG side chains are synthesized. They exhibit exceptional n‐type operational stability (over 60 h) in OECTs, fast switching (<10 ms), and excellent ambipolar behavior. Increasing the length of side chains enhances the hydrophilicity of the materials, thereby boosting electrochemical doping efficiency. This study reveals EG substitution's impact on NDI‐2Tz copolymers, providing insight for stable, low‐power n‐type/ambipolar materials.