Direct (hetero)arylation Polymerization, Electrochemical and Optical Properties of Regioregular 3-Substituted Polythiophenes with Alkylsulphanyl and Alkylsulfonyl Groups

Regioregular polythiophenes have been widely used in organic semiconducting applications due to their crys-tallinity 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 H-1 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 crys-tallographic analysis of these synthetic polymers.