Correlation between the hierarchical structure and electrical conductivity of PEDOT/PSS

The correlation between the hierarchical structure and electrical conductivity of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) was investigated by means of X-ray photoelectron spectroscopy, wide-angle X-ray diffraction, conductive atomic force microscopy and the temperature dependence of the electrical conductivity. Upon adding 3% ethylene glycol (EG), the electrical conductivity at room temperature significantly increased from 3 to 175 S cm(-1), while a further increase in EG up to 20% resulted in a decrease in the electrical conductivity to 117 S cm(-1). It was found that the improvement in the electrical conductivity could be explained from the changes in the hierarchical structure; a decrease in the insulating PSS shell, crystallization of the PEDOT and aggregation of the PEDOT/PSS particles, which affect both the intra-and interparticle transport of charge carriers.