Green-Solvent-Processed Amide-Functionalized Conjugated Polymers Prepared via Direct Arylation Polymerization (DArP)

Organic electroactive materials that can be processed using simple alcohols, such as ethanol and 1-butanol, are highly desired, since these solvents can be sourced from biomass and present lower hazards for human and environmental health. Herein, we report the first class of poly(3-alkylamidethiophenes) (P3AAT) synthesized via the sustainable method of direct arylation polymerization (DArP) that can be processed using green, sustainable solvents. The unprecedented synthesis of P3AAT reveals the superiority of DArP, as P3AAT can be readily prepared in only three simple steps with an M-n of up to 15.4 kDa and yields of up to 90% exclusively with this methodology. The tertiary amide, poly(N-hexyl-N-methylthiophene-3-carboxamide-2,5-diyl) (P1), has excellent solubility in the green solvents ethanol, 1-butanol, and anisole. Processing of P1 in 1-butanol is shown to provide comparable space-charge-limited current (SCLC) hole mobility versus dichlorobenzene and commensurate photophysical properties. Also, the secondary amide, poly(N-(2-ethylhexyl)-thiophene-3-carboxamide-2,5-diyl) (P2), was successfully synthesized, demonstrating excellent functional group tolerance for DArP, while showing hydrogen-bonding features and similar SCLC hole mobility as P1. This study provides a facile synthetic strategy for a novel structural motif that can be processed in sustainable solvents without a compromise in performance, which can easily be extended to other valuable areas of organic electronics and bioelectronics.