Optical and Electrical Properties of Graphene Percolated Networks from Liquid Exfoliation of Graphite

Abstract

Thin films obtained from liquid phase exfoliation of graphite exhibit the conductivity and transparency properties of percolated networks having an interconnectivity distance of about 2 micrometers to 3 micrometers. The mean radius of the platelets in solution determined by dynamic light scattering measurements was found to be in the range of about 3 micrometers. Representative transmittance electron microscope images show evidence of individual graphene sheets. The platelets have an irregular shape with apparent folding and bending, which contributes to disorder and imperfections of the films as revealed by the Raman spectra. The scaling universal exponents describing the percolation transition from an insulating, 100 % transparent state, to a transparent, conducting state are consistent with the two-dimensional (2D) percolation model. These findings provide a framework for engineering the optical and electrical properties of graphene networks for technological applications where flexibility, transparency, and conductivity are required.