Origin of different electrical conductivities in PEDOT:PSS

Abstract The different grades of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) (Clevios P, PH500, and PH1000) were investigated to clarify the origin of the different electrical conductivities using X-ray photoelectron spectroscopy, dynamic light scattering, reflectance spectroscopy, X-ray diffraction, conductive atomic force microscopy, and Raman spectroscopy. The electrical conductivity ( σ ), crystallinity ( X c ), and carrier mobility ( μ ) increased in the order of Clevios P, PH500, and PH1000, whereas the composition ratio ( α ) and carrier density ( N c ) were almost the same. The results allowed us to conclude that the mechanism of different σ in the PEDOT:PSS lay in μ , where high X c with large size ( D nc ) and number ( N nc ) of PEDOT nanocrystals uniformly distributed within the PSS matrix favored carrier transport between adjacent nanocrystals, resulting in high σ in the bulk state.