Using boronic acid functionalization to simultaneously enhance electrical conductivity and thermoelectric performance of free-standing polythiophene film

Abstract

Poly(3-thiophene boronic acid) (PTBA) as a boronic acid functionalized conducting polymer has been developed in sensors and electrochromics due to the characteristic feature of boronic acid groups, however, the previously reported PTBA had a very low electrical conductivity of 2.0 × 10−9 S cm−1, and up to day there are no researches on PTBA used as thermoelectric materials. In this study, a free-standing PTBA film with high-quality was firstly electrosynthesized in acetonitrile containing boron trifluoride diethyl etherate (1:1 by volume). SEM, FT-IR, UV–vis and TG were conducted to investigate morphologies, structures and thermal stability of PTBA films. Notably, the introduction of boronic acid groups in polythiophene significantly increases the Seebeck coefficient from 72.5 to 125.0 μV K−1, electrical conductivity from 0.014 to 0.027 S cm−1, and power factor from 0.0074 to 0.0422 μW m−1 K−2. Free-standing PTBA film will be a promising material in the field of thermoelectric.