High Iontronic Performance in Organic Electrochemical Transistors Enabled by Intramolecular Noncovalent Interactions

Organic electrochemical transistors (OECTs) show great potential in bioelectronics due to their iontronic coupling, low driving voltages (<1 V), and biocompatibility. Nevertheless, their low iontronic performance, particularly in terms of transconductance (g_m), limits their ability to acquire high-precision biosignals. To address this issue, a series of poly(bithiophene)s (opg2T-O, opg2T-S, and opg2T-Se) bearing 4,4'-position glycol side chains are synthesized. Upon varying furan, thiophene, and selenophene comonomers, the intramolecular noncovalent interactions are systematically tuned. Comprehensive theoretical analyses reveal that opg2T-Se demonstrates stronger intramolecular Se···O noncovalent interactions than the S···O interactions in opg2T-S and opg2T-O, affording a more planar and rigid molecular configuration in opg2T-Se. Meanwhile, opg2T-Se exhibits closer π-π stacking and lamellar-packing and prefers an edge-on orientation. Consequently, a record-high geometry-normalized transconductance (g_m,n) of 415 S cm^-1, along with remarkable hole mobility (µ = 2.99 cm² V^-1 s^-1) and volumetric capacitance (C* = 423.3 F cm^-3) are achieved in opg2T-Se based OECTs. Importantly, the opg2T-Se-based devices exhibits much higher signal fidelity in in-vitro human electrocardiogram (ECG) than the other two devices. This study highlights the importance of intramolecular noncovalent interaction in the channel layer materials for achieving high-performance OECTs.