As a potential risk to human and environmental health, radio frequency (RF) radiation should be studied due to the higher frequencies and larger bandwidths that may be employed. Electromagnetic interference (EMI) shielding materials can prevent exposure to RF radiation, but most of them are visibly opaque. In this work, we propose and fabricate visibly transparent EMI shielding materials using an ultrathin silver layer sandwiched by oxides (SLSO) as building blocks. The samples with a double-sided SLSO (D-SLSO) structure exhibit the highest EMI shielding effectiveness (SE) of 70 dB at 27.6 GHz (>62 dB on average at 4–40 GHz) and a transmittance close to 90% at a visible wavelength of 550 nm, which is comparable with those of polyethylene terephthalate (PET) and glass substrates. The D-SLSO structure plays a dual role: it suppresses optical reflections as antireflection coatings and enhances EMI shielding via Fabry–Pérot interference. In addition, we discuss the origin of the extraordinary frequency dependence of SE, which monotonically increases, contrary to that of conventional metallic mesh. This report describes SLSO-based transparent EMI shielding materials with record-high SE and visible transmittance that provide optoelectronic applications with robust safety and reliability under RF radiation with high and broad frequencies.

We propose a multi-cavity resonant architecture that is established by employing two opposing ultrathin silver-based films to form a Fabry–Pérot (F–P) cavity and inserting one or two metallic mesh layers in between. Compared with the single F–P cavity, the multi-cavity architecture with one metallic mesh layer experimentally exhibits a ∼ 37 % improvement in the average shielding effectiveness and maintains a transmittance over 80% at 550 nm. A more significant improvement of ∼ 108 % in shielding effectiveness (SE) can be achieved by inserting two metallic mesh layers. The proposed multi-cavity architecture provides a strategy for removal of the hindrance to transparent electromagnetic interference shielding.

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