Novel conducting poly(3,4-ethylenedioxythiophene) – Graphene nanocomposites with gigantic dielectric properties and narrow optical energy band gap.

Novel nanocomposites, consisting of conducting poly(3,4-ethylenedioxythiophene) [PEDOT] and graphene nanoplatelets [GNPs], were successfully synthesized by in-situ chemical-oxidative polymerization of 3,4-ethylenedioxythiophene [EDOT] using ammonium peroxydisulfate as an oxidizing agent. The formation of PEDOT and its incorporation onto the surface of GNPs were confirmed by scanning electron microscopy, Fourier-transform infrared-spectroscopy, and X-ray diffraction. The optical energy band gap, E g opt, was determined by UV–Vis spectroscopy. Dielectric constant and loss as well as AC electrical conductivity, σ AC , were determined in the frequency range from 10 Hz to 8 MHz. The PEDOT-GNP nanocomposites were found to have extremely large dielectric constant, ε ′, significantly high σ AC , and narrow E g opt values. In particular, PEDOT-GNP nanocomposite with 10 wt% GNP has a gigantic dielectric constant of the order of 9 × 105 at 1 kHz and a narrow optical energy band gap of 1.26 eV. The ε ′ values (108 to 105 in the frequency range from 10 Hz to 5 MHz) of PEDOT-10 wt% GNP are the highest among those reported in the literature for carbon based polymer nanocomposites. The massive quantity of micro-capacitors formed in the nanocomposites, prior to the creation of conductive networks, leads to the gigantic dielectric properties. The ε ′ and σ AC values of PEDOT-10 wt% GNP nanocomposite were about 90 and 400 times larger than those of pure PEDOT. Our method should be particularly promising in the development of new materials for high energy storage applications. • PEDOT-GNP nanocomposites are synthesized by in-situ chemical oxidative polymerization. • Dielectric constant, ε ′, band gap, E g opt, and AC conductivity, σ AC , vary with GNP content and frequency. • PEDOT-10 wt% GNP nanocomposite has a gigantic ε ′ of the order of 9 × 105 at 1 kHz and a narrow E g opt of 1.26 eV. • ε ′ and σ AC values of PEDOT-10 wt% GNP nanocomposite are 90 and 400 times larger than those of pure PEDOT. • PEDOT-10 wt% GNP nanocomposite has shown highest ε ′ values for carbon based polymer nanocomposites. [ABSTRACT FROM AUTHOR]