A Review on Electrical Properties of Graphene and Percolation Threshold of Graphene Based Coatings

Graphene is a monolayer two-dimensional material in which the carbon atoms form a honeycomb lattice. The outstanding electrical, thermal, optical and mechanical properties of graphene due to its electronic structure have made graphene a promising nanostructure for vast range of applications. In this zero-gap semiconductor material, electron/ hole carriers concentration is around 〖10〗^13 cm^(-2) and it possesses high electron mobility (500000 s^(-1) V^(-1) cm^2) at room temperature. Adding graphene to a polymeric matrix enhances the polymer properties noticeably, various researches have been devoted to studying the fabrication methods of polymer/graphene coatings and achieving the optimum properties in them. In this paper, the general structure, properties and various procedures of graphene production are briefly investigated. Then the fabrication methods of polymer/graphene coatings are studied. The main part of this paper has focused on electrical conductivity of various coatings based on epoxy, polyurethane, polypropylene, polystyrene, polyester and etc. In which achieving the lowest possible electrical percolation threshold (minimum amount of graphene required to convert an insulator coating to a conductor), finding and controlling the factors that affect the percolation threshold are discussed.