Nanostructured, Highly Flexible, Optically Transparent EMI Shielding Thin Film for Smart Electronics

A lightweight, highly flexible and optically transparent nanostructured thin film for electromagnetic interference (EMI) shielding of smart devices is presented. The proposed thin film is based on the novel optically transparent long silver nanowires (AgNWs), which is especially synthesized here to form the polyethylene terephthalate (PET) integrated AgNWPET sheet of 0.1 mm to ascertain adequate EMI shielding in the designated frequency band. The fabricated AgNWPET sheets are tested using the vector network analyzer, and the AgNWPET4 film (R_s value 23.5 Ω/sq) shows the total shielding effectiveness (SE_T) of 19 dB in X-band. The AgNWPET4 sheet is also modeled using the conductive sheet model and the CST Microwave Studio, and the simulated SE_T values agree closely with the experimental data. Both simulations establish that the AgNWPET4 sheet provides an adequate SE_T value greater than 19 dB across 1–18 GHz frequency range. The nanostructured percolation network in the present situation ensures 67% optical transparency for AgNWPET4 film. Further, a 60 μm thick transparent polyvinyl butyral layer is applied to AgNW networks to prevent the shedding of AgNWs. The resulting sandwiched thin film (AgNWPETPVB) provides an optical transparency of over 62% in the visible range, with a total thickness of just 0.16 mm. The proposed optically transparent flexible thin film can potentially be used for next-generation EMI shielding of various types of smart electronic devices and systems.