Scalable Ion‐Electron Coupled Poly(Benzodifurandione) Inks Enabling Biosignal Amplification and Neuromorphic Memory

ABSTRACT Printed organic electrochemical transistors (OECTs) are promising for next‐generation biosensing and neuromorphic computing, owing to their high transconductance, low operating voltage, mechanical flexibility, and efficient volumetric ionic–electronic coupling. Yet, printable n ‐type OECTs have lagged their p ‐type counterparts due to limited stability and poor printability. The key challenge lies in achieving high electronic conductivity, efficient ionic accessibility, and rheological properties compatible with scalable printing. To address this, we developed a screen‐printable, air‐stable, n ‐type OECT channel by blending high‐conductivity poly(benzodifurandione) (PBFDO) with poly(ethylene oxide) (PEO). Devices fabricated using 5wt.% PEO blend and a gelatin‐based electrolyte exhibited tunable transient responses (turn‐on time; 9.6 to 419 ms, turn‐off time; 4.3 ms to 17.8 ms), stable operation (92.4% ON current retained over 1,000 cycles), and high uniformity across 50 devices (I ds, ON = 2.47 ± 0.29 mA and transconductance g m = 3.55 ± 0.57 mS). PEO transforms low‐viscosity PBFDO solutions into shear‐thinning pastes suitable for screen printing, while enhancing film wettability and electrolyte infiltration. This dual role promotes efficient ion penetration and improves printability, enabling devices with improved transient speeds and rheological properties optimized for scalable fabrication. By controlling channel thickness, thin devices enable electrocardiogram signal acquisition while thick devices act as artificial synapses, highlighting PBFDO‐based inks as versatile platforms for integrated bioelectronic interfaces.