Electro-polymerization of PEDOT with a three-armed conjugated crosslinker leads to enhanced charge transport

Poly(ethylenedioxythiophene)-based polymers (PEDOT) have emerged as versatile materials for transparent conducting electrodes, electronics for biointerfacing, and organic thermoelectrics – interconversion of heat and electricity. Here, we report on the co-electropolymerization of EDOT with a three-armed conjugated crosslinker TTB (1,3,5,-tri(2-thienyl)-benzene). Through a systematic variation of TTB concentration, we show the incorporation of low levels of TTB leads to enhanced electronic conductivity relative to neat electropolymerized PEDOT films. We attribute the increase in electronic conductivity to enhanced pi-pi interaction of the polymer chains and enhanced conjugation with the TTB crosslinking unit. In addition, to probe the utility as conductive electrode films, electrochemical ac impedance spectroscopy reveals that the incorporation of TTB leads to reduced film impedance in electrolytic solutions at low and high frequencies. Lastly, tuning the charge carrier concentration through controlled oxidation, we show an enhancement in the thermoelectric power factor at low TTB concentrations. Overall, our work conveys the utility of using a three-armed conjugated crosslinker for enhanced charge transport in PEDOT-based platforms.