Humidity sensing properties of graphene quantum dots

This paper presents the intrinsic humidity sensing response obtained using graphene quantum dots. Graphene quantum dots of 4.5 nm average diameter are found to have very high sensitivity to ambient water molecules. Resistance of prepared films was found to decrease with increasing humidity levels and a change in resistance of the order of 104 is measured. The prepared devices were shown to respond to a wide range of relative humidity levels with a fast response time near 8 seconds. The high sensitivity obtained is attributed to the reversible physisorption of water molecules, which also serve as p-type dopants.