Conformational and Electron Dynamics Changes Induced by Cooling Treatment on GO:PEDOT:PSS Transparent Electrodes

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.