Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), PEDOT:PSS, is a polymeric composite that can substitute indium tin oxide (ITO), enabling ITO-free organic devices. However, PEDOT:PSS films have conductivities two orders of magnitude lower than ITO due to the presence of PSS, an insulator polymer added to provide water dispersion to PEDOT. To enhance the electrical performance of the films and overcome the insulator limitations, we prepared thin films of graphene oxide (GO) and PEDOT:PSS composites. The dried films were then treated with ethylene glycol (EG). An increment of two orders of magnitude in conductivity values was observed, as well as an increase in transmittance at the visible region. Also, GO:PEDOT:PSS thin films became more hydrophobic due to the partial removal of PSS. The mass ratio that is equal to 0.058 of GO/PEDOT provides higher electrical conductivity due to higher chain orientation of PEDOT as seen in the near edge X-ray absorption fine structure and resonant Auger spectroscopy measurements. The electrical transport follows the Mott Variable Range Hopping model for low temperature, showing that the conduction occurs in three dimensions. The solvent treatment increases the characteristic conductivity and decreases the activation hopping energy, with the characteristic temperature remaining almost unchanged. It indicates that the EG treatment promotes a decrease in charge transfer time and resistivity.

Due to issues related to the use of indium, the conjugated polymer poly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate) (PEDOT:PSS) is considered as one of the main substitutes for indium tin oxide (ITO) in the structure of organic photovoltaics. Recent works demonstrated that the blend of PEDOT:PSS and graphene oxide (GO) can provide transparent and flexible electrodes with a higher efficiency than PEDOT:PSS itself. In this study, two series of cooled and not-cooled thin films of GO:PEDOT:PSS with different compositions of PEDOT:PSS (1, 5, 10, and 100% (v/v)) were investigated by spectroscopic and morphological techniques to evaluate the effect of the cooling treatment on their electronic and chemical structures, morphology, and carrier mobility. Surface- and bulk-sensitive near-edge X-ray absorption fine structure (NEXAFS) results probed at the sulfur K-edge showed that the cooled GO:PEDOT:PSS 5% blend is the most organized film, which also presented a faster electron delocalization time as probed by resonant Auger spectroscopy using the core-hole clock method. GO:PEDOT:PSS 5% offers the best synergetic effect among the blends, a result which is completely in agreement with electrical results.

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