Electromagnetic shielding effectiveness of a thin silver layer deposited onto PET film via atmospheric pressure plasma reduction

Highlights: • A thin silver film is directly deposited on PET film by using dry plasma reduction. • A uniform thin film is obtained after 5-time dry plasma reduction with 500 mM AgNO₃ solution. • The film exhibits the highest electromagnetic interference shielding effectiveness. • The porosity, size and number density of Ag NPs are key factors for high effectiveness. • This finding is promising for fabricating various low-cost metal films at low temperature. This study presents the first use of a plasma reduction reaction under atmospheric pressure to fabricate a thin silver layer on polyethylene terephthalate (PET) film without the use of toxic chemicals, high voltages, or an expensive vacuum apparatus. The developed film is applied to electromagnetic interference (EMI) shielding. After repeatedly depositing a silver layer through a plasma reduction reaction on PET, we can successfully fabricate a uniformly deposited thin silver layer. It was found that both the particle size and film thickness of thin silver layers fabricated at different AgNO₃ concentrations increase with an increase in the concentration of AgNO₃. However, the roughness of the thin silver layer decreases when increasing the concentration of AgNO₃ from 100 to 500 mM, and the roughness increases with a further increase in the concentration of AgNO₃. The EMI shielding effectiveness (SE) of the film is measured in the frequency range of 0.045 to 1 GHz. As a result of optimizing the electrical conductivity by measuring sheet resistance of the thin silver layer, the film fabricated from 500 mM AgNO₃ exhibits the highest EMI SE among all fabricated films. The maximum values of the EMI SE are 60.490 dB at 0.1 GHz and 54.721 dB at 1.0 GHz with minimum sheet resistance of 0.244 Ω/□. Given that the proposed strategy is simple and effective, it is promising for fabricating various low-cost metal films with high EMI SE.