Extrinsic n-Doping of a Double B←N Bridged Bipyridine-Based Polymer Containing Oligoethylene Glycol Side Chains

Organic mixed ionic-electronic conductor (OMIEC) polymers with the ability of mixed charge transport have been widely used in organic electronic devices, such as organic thermoelectric transistors (OTEs) and organic electrochemical transistors (OECTs). The development of an n-type OMIEC remains a grand challenge. Herein, a double B←N bridged bipyridine unit with strong electron deficiency is used to build acceptor-acceptor type conjugated polymers (PBN-alkyl and PBN-OEG). PBN-OEG with oligoethylene glycol side chains exhibits weaker crystallinity, improved doping efficiency, and superior ion uptake capacity relative to the counterpart polymer with alkyl side chains. As a result, PBN-OEG exhibits a higher conductivity of 1.95 S cm–1, a better power factor of 4.7 μW m–1 K–2 in OTEs, and a large μC* of 2.6 F cm–1 V–1 s–1 in OECTs. Such results demonstrate the great potential of acceptor-acceptor type organoboron polymers for OMIEC materials.