n-Type Rigid Semiconducting Polymers Bearing Oligo(Ethylene Glycol) Side Chains for High-Performance Organic Electrochemical Transistors

N-type conjugated polymers as the semiconducting component of organic electrochemical transistors (OECTs) are still undeveloped with respect to their p-type counterparts. Herein, we report two rigid n-type conjugated polymers bearing oligo(ethylene glycol) (OEG) side chains, PgNaN and PgNgN, which demonstrated an essentially torsion-free π-conjugated backbone. The planarity and electron-deficient rigid structures enable the resulting polymers to achieve high electron mobility in an OECT device of up to the 10⁻³ cm² V⁻¹ s⁻¹ range, with a deep-lying LUMO energy level lower than −4.0 eV. Prominently, the polymers exhibited a high device performance with a maximum dimensionally normalized transconductance of 0.212 S cm⁻¹ and the product of charge-carrier mobility μ and volumetric capacitance C* of 0.662±0.113 F cm⁻¹ V⁻¹ s⁻¹, which are among the highest in n-type conjugated polymers reported to date. Moreover, the polymers are synthesized via a metal-free aldol-condensation polymerization, which is beneficial to their application in bioelectronics.