Re-organized graphene nanoplatelet thin films achieved by a two-step hydraulic method

Film deposition of graphene nanoplatelets (GNPs) from dispersion via casting and printing approaches features cost- and material-efficiency, however, it usually suffers from poor uniformity, rough surface and loose flake stacking due to adverse effect of hydraulic force. Here, a simple two-step method exploiting hydraulic force is presented to readily deliver GNP films of improved quality from an aqueous dispersion. While as-deposited GNP films exhibit the aforementioned film defects, the hydraulic force in the subsequent step constituting soaking in water and drying leads to an efficient re-organization of the individual GNPs in the films. The majority of GNPs thus are oriented horizontally and closely stacked. As a result, densified, smoothened and homogenized GNP thin films can be readily achieved. The GNP re-organization reduces resistivity from >1 Ω cm to 10⁻² Ω cm. The method developed is universally applicable to solution-phase film deposition of 2D materials.