Graphene-based EMI shield obtained via spray deposition technique

In this work we investigate the shielding properties of graphene-based films, produced by spray casting deposition, which is a cost-effective technique that can be directly scaled to industrial applications. The deposition process is optimized in order to produce uniform films made of well dispersed graphene nanoplatelets (GNP), having thicknesses in the range 3-8 microns. The sheet resistance and the shielding effectiveness up to 18 GHz of films produced using GNP-suspensions at different concentrations are measured and compared with the ones of carbon nanotube (CNT)-based films, produced in the same conditions. The obtained results demonstrate the superior shielding properties of graphene-based films with respect to CNT-ones, mainly due to the bi-dimensional shape of GNPs, which contributes to minimizing the contact resistances among adjacent nanostructures. It is also demonstrated that after a thermal annealing at 250°C, the final measured shielding effectiveness of the produced GNP-film triplicates in linear scale, reaching the value of 30.6 dB.