Electrical conductivity of graphene films with a poly(allylamine hydrochloride) supporting layer

The electrical conductivity of graphene oxide (GO) and reduced graphene oxide (RGO) films with poly(allylamine hydrochloride) (PAH) supporting layers is investigated. Graphene-PAH hybrid films were produced in a two-step procedure that consisted of vacuum filtration for GO (or RGO) dispersion to fabricate the graphene thin films on quartz substrates, followed by the deposition of PAH onto the graphene films via solution casting. Highly selective deposition of the PAH layer on the graphene sheets was confirmed through the detection of the fluorescence signals of hybridized Cy3-DNA onto the PAH-coated graphene surfaces. In this case, electrostatic interaction plays an important role in the selective deposition process. Interestingly, it was found that the electrical conductivity of RGO films was significantly enhanced by 120% after PAH treatment, whereas that of the GO films was reduced by 98% of its initial conductivity. This finding was interpreted in terms of the molecular structure and oxygen functionalities of GO and RGO films combined with the ionic conduction characteristics of hydrated PAH on the RGO film.