Dielectric Properties and AC Conductivity Studies in PEDOT-PSS/EG/GO Composites with Ultrahigh Permittivity

The development of high-permittivity materials with low loss has been explored for their potential in energy storage applications. Polymer composites with high breakdown strength are candidate materials but often find limited energy properties due to their low dielectric constant. Herein, a polymer composite based on an intrinsically conducting polymer, PEDOT-PSS, and a carbon-based filler, graphene oxide (GO), with ultrahigh permittivity, is reported. This study employs the impedance spectroscopy technique to investigate the dielectric properties and AC conductivity of GO-incorporated PEDOT-PSS/EG composites. A free-standing composite film with lower filler addition achieved a high permittivity of 1.1 × 106 with minimal loss tangent. The incorporation of GO leads to the formation of insulating and conducting clusters in a microcapacitor arrangement in the composite system, resulting in Maxwell–Wagner–Sillars (MWS) polarization. Equivalent circuit analysis of the Nyquist plot gives the value of the fitting parameter, a1, close to unity, thus confirming the outstanding capacitive behavior in the lower-loading composite samples with the successful formation of the microcapacitors. Temperature-dependent AC conductivity studies revealed that conduction process in the composite occurs by non-overlapping small polaron tunneling mechanism. The PEDOT-PSS/EG composite with lower filler loading showed a maximum energy density value of 2 J/cm3 at a 6.5 × 105 V/m electric field.