Metal mesh-based transparent electrodes as high-performance EMI shields

Electromagnetic interference (EMI) shields in the form of coatings and films are useful for blocking radiations in various household and industrial settings. Being transparent and flexible would enhance their utility domain. In this study, we have fabricated transparent and flexible EMI shields made of metal meshes produced using the crack templating method pioneered in the laboratory. A Cu metal mesh with polyethylene terephthalate (PET) sheet as its substrate exhibited a visible transmittance of ∼85% and a sheet resistance of ~0.83 Ω per square. The shielding efficiency was tested over a wide spectral range of the Ku band (12–18 GHz), relevant to communication electronics. The Cu mesh/PET film showed a remarkably high value for total EMI shielding (SET) with the average value being ~41 dB. The film could be laminated using a commonly available method, thus protecting exposure of the mesh to the environment. The laminated film is multifunctional, and this aspect was demonstrated by fabricating a large area (3.5 × 2.2 cm2) Joule heater for defrosting and defogging applications.