Remote-Controllable Lateral Electropolymerization of Conducting Polymers via Dual-Electrode ADC-Bipolar Electrochemistry

The electrolysis of aromatic molecules is a useful method for the synthesis and deposition of conducting polymers. However, this method cannot be applied to diverse large-area electronic devices because films grow vertically on the surface of an electrically connected working electrode. Herein, the remote-controllable lateral electropolymerization of 3,4-ethylenedioxythiophene using direct-current voltage superimposed alternating-current voltage (ADC)-bipolar electrochemistry is reported. The use of shape-designed dual bipolar electrodes and systematic optimization of the process parameters led to the fabrication of uniform poly(3,4-ethylenedioxythiophene) (PEDOT) films on 2-inch glass wafers and flexible plastic substrates. The oxidation levels and microstructures of ADC-electropolymerized PEDOTs with various supporting electrolytes are investigated and correlated with their thermoelectric properties. A soft thermocouple and resistive-type gas sensor based on an ADC-electrodeposited PEDOT are demonstrated to monitor cerebral temperature in a brain replica and to sense nitrogen dioxide gas, respectively.