Synthesis and characterization of nano silver-modified graphene/PEDOT:PSS for highly conductive and transparent nanocomposite films

A solution-processed metal nanoparticle/graphene composite thin film is developed by the functionalization of reduced graphene oxide (f-RGO) nanosheets with SH and SO3Na functional groups. The RGO is prepared by the oxidation of natural graphite powder and the thermal reduction of graphene oxide (GO). The f-RGO nanosheets show an improved dispersion in water through salty groups (SO3Na) and a high affinity to silver ions via thiol groups. After a simple in-situ reduction method, Ag NPs, with particle size ca. 10 nm, can be distributed uniformly on the surface of f-RGO and utilized as conductive spacers between the graphene nanosheets. Due to the strong π-π interactions between a graphene nanosheet and a rigid backbone of PEDOT, the Ag-decorated f-RGO nanosheets (Ag@f-RGO) can be well dispersed within poly (3,4-ethylenedioxythiophene):poly (stryene sulfonate) (PEDOT:PSS) to develop highly transparent conductive films. This solution-based method permits the resulting nanocomposite thin film to maintain the intrinsic electronic property of both components, showing a hybrid thin film with a high conductivity of 2078 S/cm and a transmittance of 88 % at a wavelength of 550 nm. By making good use of the conducting network built up by the graphene and conducting polymer, we demonstrate the promising application of Ag@f-RGO/PEDOT:PSS nanocomposite thin film as highly conductive and transparent electrodes for organic photovoltaic devices.