Reduced graphene oxide prepared at low temperature thermal treatment as transparent conductors for organic electronic applications

Abstract

In this work, we obtain transparent conducting thin films of both chemically and thermally reduced graphene oxide. High-quality films are normally obtained with thermal treatments at temperatures about 1000 °C, while the highest temperatures employed during the thermal treatment in this work were as low as 400 °C, which is a mandatory condition when dealing with organic electronic devices on glass substrates. To reach such a low thermal treatment, a two-step oxidation process was employed in order to allow the formation of carbonyl chemical groups rather than epoxy functionalization. Each GO sample was structurally and chemically analysed by Infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), Ultraviolet–visible absorption spectroscopy (UV-VIS), Thermogravimetric analysis (TGA), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The GO conducting thin films exhibited a sheet resistance of 3.2 × 103 Ω/sq as well as a high transmittance: up to 80% at 550 nm. Furthermore, Raman spectroscopy, X-ray diffraction and AFM show that the thermally reduced thin films are mainly composed of single and bilayer GO sheets with a very low average roughness. Also, these GO thin films, with such surprising quality, have been employed as non-doped and metal free electrodes in organic light emitting diodes.