Influence of dispersion of multi-walled carbon nanotubes on the electrochemical performance of PEDOT–PSS films

In this work, multi-walled carbon nanotubes (MWCNTs) were chemically treated using ethylene glycol (EG) to improve their dispersion in poly(3,4-ethylene dioxythiophene)–poly(4-styrenesulfonate) (PEDOT–PSS). The surface resistance, transmittance, and electrochemical properties of the chemically treated MWCNTs (EG-MWCNT)/PEDOT–PSS films prepared by spray-coating were investigated. The effect of polar solvents on the electrochemical properties of the films was also determined. It was found that the EG-MWCNTs, well dispersed in the PEDOT–PSS, formed a conductive network after spray-coating. The surface resistance and transmittance of the films decreased as the number of coatings increased. The surface resistance of the films was further decreased with the addition of polar solvents. In addition, the current density of the EG-MWCNT/PEDOT–PSS was enhanced remarkably by polar solvent doping. It was noted that polar solvents having a high dielectric constant led to stabilization and high dispersity of the negative charged EG-MWCNTs and provided a screening effect between PEDOT and PSS, resulting in an increase of the electric and electrochemical properties.