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

Abstract

N-type conjugated polymers as the semiconducting component of organic electrochemical transistors (OECTs) are still undeveloped with respect to the p-type counterparts. Herein, we first 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 10 -3 cm 2 V -1 s -1 range, with a deep-lying lowest unoccupied molecular orbital (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. Our work proves a new way for designing glycolated n-type conjugated polymers with low-lying LUMO and conformation-locked backbones for high performance OECTs.