Engineering D-A Conjugated Polymers for High-Performance Organic Electrochemical Transistors—Insights into Structural Design and Molecular Organization

Organic mixed ionic-electronic conductors (OMIECs) have emerged as promising active materials for organic electrochemical transistors (OECTs) due to their dual ability to transport ions and charges. Among them, conjugated polymers functionalized with polar oligo(ethylene glycol) (OEG) side chains are highly effective in enhancing ion accessibility and facilitating efficient doping/dedoping processes. However, the inherently soft nature of glycolated polymers often results in incomplete semicrystallinity and significant disordered regions in their solid-state films, posing challenges in achieving both high charge carrier mobility (μ) and volumetric capacitance (C*). To address these challenges and improve the steady-state performance of OECTs, strategies focusing on structural design and molecular organization have been explored. Tailoring molecular structures—such as donor-acceptor (D-A) frameworks, side chain functionality, and backbone planarity—allows for the optimization of ion transport, charge mobility, and stability during operation. In particular, aligning polymer chains through side chain and backbone modifications is considered as an effective approach to constructing advanced OMIEC materials. In this work, we present insights from OEG side-chain engineering to backbone structure modifications, offering a comprehensive framework for achieving high-performance OECTs with enhanced charge transport mobility.