Temperature-Dependent Conductivity of Graphene Oxide and Graphene Oxide-Polyaniline Nanocomposites Studied by Terahertz Time-Domain Spectroscopy

In this work, we have studied the temperature-dependent conductivity of graphene oxide (GO) and graphene oxide–polyaniline (GO-PANI) nanocomposites by terahertz time-domain spectroscopy (THz-TDS) from 78 to 293 K. The refractive index and absorption coefficient are related to the conductivity, and it has been found that in the THz region, the real part of the complex conductivity of GO is less than that of GO-PANI over the entire range of experimental temperatures. Both the systems exhibit an increase in these physical parameters with increasing temperature. The complex conductivity spectra of these systems in the THz region are well fitted by an analytical model that has contributions from the scattering of free electrons (Drude–Smith term) and from bound-electron oscillation (Lorentz term). The fitting analysis suggests a more ordered structure and anharmonicity for both the systems with increasing temperature and reports that GO-PANI has a greater free electron density and damping frequency of oscillation and more ordered structures than GO at all temperatures.