Ambient direct arylation synthesis of thienothiophene based copolymers with mixed alkoxy and oligoether side chains

Abstract

[Abstract]: Conjugated polymers with both oligoether and alkoxy side chains are an emerging type of organic mixed ionic-electronic conductor. Here, direct arylation polymerization is introduced as a viable synthetic route for such materials. The composition and molecular weight of the synthesized thienothiophene-based random copolymers are determined with high-temperature 1H NMR spectroscopy. Chemical and electrochemical doping of the copolymers reveal that the introduction of a minor fraction of alkoxy side chains results in materials with a highly promising set of electrical and mechanical properties. A copolymer with an alkoxy side-chain fraction of 12% features an electrical conductivity of 390 S cm−1 and a charge-carrier mobility of more than 3 cm2 V−1 s−1. Organic electrochemical transistors with a NaCl aqueous electrolyte feature a high figure of merit of 1313 F cm−1 V−1 s−1 thanks to a high volumetric capacitance of 417 F cm−3. Evidently, the introduction of a minor fraction of alkoxy side chains is a viable route for improving the electrical properties of organic mixed ionic-electronic conductors.