Graphene paper for exceptional EMI shielding performance using large-sized graphene oxide sheets and doping strategy

Large-sized graphene sheets (LG) and doping strategy were employed to fabricate lightweight and flexible graphene paper with exceptional electromagnetic interference (EMI) shielding performance. Compared with the smaller sized ones, LG with fewer defects and more conjugated carbon domain size as well as better alignment result in higher electrical conductivity and strength of graphene paper. The iodine doping further improves the carrier density of LG by formation of triiodide (I3−) and pentaiodide (I5−) through charge transfer process without deteriorating the mechanical property, thus leading to superior EMI shielding effectiveness (SE). The EMI SE of iodine doped LG film with thickness of 12.5 μm is up to ∼52.2 dB at 8.2 GHz, which is much higher than that of undoped LG with the same thickness (∼47.0 dB). More important, the improvements in EMI SE is contributed to the SE absorption, while the SE reflection is almost unchanged. The mechanisms of improved EMI shielding performance as well as mechanical property were investigated and discussed. The present study provides a facile way to fully develop graphene in lightweight and flexible EMI shielding materials and devices.

Large-size graphene oxide sheets combined with doping strategy were employed to improve the carrier mobility and carrier density of graphene. Flexible iodine-doped graphene film with exceptional EMI shielding performance was fabricated and investigated. The doped graphene paper assembled by large-sized sheets possesses higher electrical conductivity and shows EMI shielding effectiveness (SE) as high as ∼ 52.2 dB with thickness of ∼12.5 μm, which is much higher than most of reported results with the same thickness and the improvement in EMI SE is contributed to the SE absorption, while the SE reflection is almost unchanged. Furthermore, the mechanical properties can be maintained very well after the doping process. This study opens a new idea to fully develop graphene in lightweight and flexible EMI shielding materials and devices.239