Direct (hetero)arylation polymerization, electrochemical and optical properties of regioregular 3-substituted polythiophenes with alkylsulphanyl and alkylsulfonyl groups

Abstract

Regioregular polythiophenes have been widely used in organic semiconducting applications due to their crystallinity and solubility. The alkylsulfanyl and alkylsulfonyl side chains could serve as useful synthetic strategy for adjusting the electronic properties of organic semiconductors. In this paper, head-to-tail coupled and highly regioregular poly(3-octylthiothiophene)s (PTS) and poly(3-octylsulfonylthiophene)s (PTSO2) were synthesized through direct (hetero)arylation polymerization. The head-to-tail (HT) regioregularity of the polymer were determined by the widely used 1H NMR method. The HOMO and LUMO energy levels of poly(3-alkylthiophene) were lowered by adjusting the oxidation state of sulfur from sulfanyl to sulfonyl. The effects of these functional side chains are presented through UV−vis, fluorescence, and electrochemical measurements, as well as crystallographic analysis of these synthetic polymers.