A green approach to water‐based graphene ink with reverse coffee ring effect

In printing electronics, graphene is used as a functional material due to its excellent physical properties. Therefore, to prepare a conductive graphene ink that contains non-toxic and environment-friendly solvent is very important. Direct preparation of graphene from graphite using liquid-phase exfoliation process is beneficial since it is simple and easy to use. Here in this work, we have synthesized the graphene dispersion using ethanol and water by liquid-phase exfoliation method and prepared a conductive graphene ink that shows an absence of coffee ring formation during the evaporation of solvents. A film has been prepared using the prepared ink which shows the electrical resistivity 1.06 Ω-cm at temperature 300 °C.