Graphene, a monolayer of carbon atoms arranged into a two-dimensional honeycomb lattice, has attracted tremendous attention owing to its electrical, optical, thermal, and mechanical properties.[1–4] These properties suggest applications that include field-effect transistors, supercapacitors, and sensors, among many others.[5–7] Graphene oxide (GO) can be chemically reduced to obtain colloidal suspensions of reduced GO (rG-O) in organic solvents without the use of surfactants.[8–10] Such rG-O suspensions have been studied for many applications, including transparent conducting films and batteries.[11–13]

The dielectric properties of conductor-insulator composites have been previously studied.[14–16] The concentration and aspect ratio (s) of the conducting fillers in these composites, and their spatial distribution, determine the conductor-insulator transition.[14–22] Conductive fillers include metal nanoparticles, carbon nanotubes, carbon black, and carbon fibers.[14–19] The conductor-insulator composites are attracting much attention for potential applications of charge-storage capacitors, thinfilm transistors, and antistatic materials owing to their unique properties, ie, a dramatic increase in dielectric constant in the conductor-insulator composite films near the percolation threshold.[16–18] However, these films have not been used for any practical applications due to issues such as high sintering temperatures (over 1300 C for metal particles), high dielectric loss, and excessive thickness.[23–25]