Fullerene-derivative-induced hilly morphology for high-speed flexible organic electrochemical transistors

Coupled ionic/electronic transport endows organic electrochemical transistors (OECTs) with high transconductance but slow response, limiting their applications in real-time signal processing due to time delays. Strategies to accelerate the response of OECTs without compromising their amplification capabilities remain elusive, primarily due to the conflicting dynamics of ionic and electronic transport. Herein, we present a universal method that blends semiconducting polymers with the fullerene derivative PC₆₁BM to create separate electronic and ionic transport phases. The PC₆₁BM aggregates enhance electronic mobility while promoting a hilly polymer morphology, which significantly reduces ion transport distances via a pre-swelling effect. The resulting device achieves an ultra-fast normalized response time of 5.31 × 10^-7 s μm^-2 and maintains a high transconductance of g_m = 25.7 mS, enabling the multimodal recording of faint physiological signals. This work introduces a universal strategy for achieving flexible organic electrochemical devices with fast and large responses, offering promising elements for real-time edge computing hardware.