Fig. 4
Electrochemical properties of Crys-P and EG-P films. a A schematic diagram of electrochemical impedance spectroscopy (EIS) measurements (C.E.: counter electrode, R.E. reference electrode (Ag/AgCl), and W.E: working electrode (PEDOT:PSS on Au). The film area and thickness are denoted by ‘A’ and ‘d’, respectively. b Nyquist and c Bode plots acquired using the crystallized PEDOT:PSS (Crys-P) film as a working electrode. The EIS data (symbols) was fitted (black line) with an equivalent circuit model composed of a serial resistor (RS), a parallel resistor (RP), and a parallel capacitor (CP). d Plots of extracted parallel capacitance values as a function of active volume of Crys-P (red circles) and EG-P 5% ethylene glycol-treated PEDOT:PSS (black circles) films. e A bar plot of the volumetric capacitance values which were calculated from the slopes of CP vs. d×A plots in Fig. 4d
