Morphology‐Controlled Ionic‐Electronic Coupling in PEDOT:PSS Enabled by Substituent Engineering of A‐Type Grids

ABSTRACT Organic mixed ionic–electronic conductors, particularly poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), are fundamental to iontronics, yet achieving efficient ionic–electronic coupling remains challenging due to inhomogeneous phase distribution between the electronically conducting PEDOT and ionically conducting PSS domains. Here, we employ A‐type nanogrids (AGs) as molecular additives to systematically tailor PEDOT:PSS nanostructure. AG‐H (hydrogen substituent) and AG‐PhOC ₈ (octyloxybenzyl substituent) promote uniform phase distribution, enhancing PEDOT/PSS contact and improving ionic–electronic coupling. In contrast, bulky phenyl‐substituted AG‐Ph exacerbates phase separation, degrading performance. We attribute this to the ability of wedge‐shaped AG‐H and the flexible octyloxy chain of AG‐PhOC ₈ to penetrate and fragment PEDOT aggregates, while AG‐Ph acts as an interfacial spacer. In electrochemical actuation, AG‐H and AG‐PhOC ₈ ‐modified PEDOT:PSS electrodes achieve outstanding performance, with displacements >20 mm and bending angles of ≈100° under high‐frequency (1.0 Hz), low‐voltage (3.0 V) excitation, substantially exceeding pristine PEDOT:PSS and many reported electrodes. This work establishes a molecular‐level strategy for tailoring PEDOT:PSS phase structure, enabling advanced flexible actuators for soft robotics.