Variable range hopping and relaxation mechanism in graphene oxide sheets containing sp3 hybridization induced localization

Abstract

The temperature dependent electrical properties of graphene oxide prepared by the modified Hummers method are investigated using broadband dielectric spectroscopy. The morphology and structure are confirmed by X-ray diffraction pattern and scanning electron microscope images. In the present work, we have studied the electrical properties of graphene oxide employing a recently proposed novel approach of the combined conduction and dielectric Cole–Cole formalism. The extracted dc conductivity values varies from 1.9 × 10−8 to 3.5 × 10− 5 S cm−1 as a function of temperature (153–353 K), show power-law behaviour, which is explained through Mott’s variable range hopping conduction mechanism. The density of states was found to be 6.02 × 1018 cm−3 eV−1. The conduction relaxation timescales and dielectric relaxation timescales of GO are following the power law. The physical origin of the non-Arrhenius dc conductivity behaviour of charge carriers is explained through structural heterogeneity in graphene oxide introduced due to sp2 and sp3 hybridization of carbon atoms. The range of hop was calculated to be 4.7–3.8 nm with hopping energy changing from 0.37 to 0.69 eV as a function of temperature.