Effect of solvent on PEDOT/PSS nanometer-scaled thin films: XPS and STEM/AFM studies

We have investigated effect of solvent on poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS) nanometer-scaled thin films by means of a scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) in terms of thickness and PEDOT:PSS ratio of the films. As a result, the PEDOT:PSS ratio, surface roughness, number of highly conductive grain, and thickness of the PEDOT/PSS thin film coincidently increased with the addition of ethylene glycol (EG). It suggests that primary nanoparticles decrease in size but aggregate by removing excess PSS after the addition of the EG.