Abstract
This work concentrates on preparing a film with flexibility, transparency and high electromagnetic interference shielding efficiency (EMI SE). With these properties, it can be used on monitors, glass or outer cases of electronics. Therefore, we coated graphene, conductive ink and silver grid on flexible PET substrates as shielding materials and then investigated the influence of the stacked structure on sheet resistance, EMI SE and transparency. The sheet resistance, EMI SE at frequency of 1.2 GHz and transparency of the conductive ink film containing 1 wt% functionalized graphene are 562.57 ± 9.54 Ω/sq, 3.72 dB and 97.36%, respectively, and they are 28.17 ± 14.35 Ω/sq, 23.42 dB and 93.45% for 1.0 mm spacing grid. After the aforementioned samples were hot pressed together, the transparency is measured to be 82.71%, while the EMI SE and sheet resistance become 37.50 dB and 1.86 ± 0.09 Ω/sq, respectively. The enhancement of EMI SE and the reduction of sheet resistance were due to that the conductive film tends to fill in the vacancies among grids and voids between silver particles after the hot pressing process, which compacts them tightly.