Highly Transparent and Broadband Electromagnetic Interference Shielding Based on Ultrathin Doped Ag and Conducting Oxides Hybrid Film Structures

TLDR

Electromagnetic interference across a broad radio‑frequency band must be mitigated, yet existing shielding materials trade off optical transparency, flexibility, and fabrication simplicity, limiting their use in flexible electronics. This work seeks to create an ultrathin, transparent EMI shield by doping silver with copper during sputtering. The authors fabricated an 8‑nm continuous doped‑Ag film via copper‑assisted sputtering and evaluated it as a conductive dielectric‑metal‑dielectric structure. The resulting EMAGS film transmits 96.5 % visible light, achieves an average shielding effectiveness of ~26 dB over 32 GHz, exceeds 30 dB when two layers are stacked, reaches up to 50 dB with quarter‑wavelength spacing, remains stable under repeated bending, and can be mass‑produced by roll‑to‑roll sputtering for wearable and safety applications.

Abstract

Reducing electromagnetic interference (EMI) across a broad radio frequency band is crucial to eliminate adverse effects of increasingly complex electromagnetic environment. Current shielding materials or methods suffer from trade-offs between optical transmittance and EMI shielding capability. Moreover, poor mechanical flexibility and fabrication complexity significantly limit their further applications in flexible electronics. In this work, an ultrathin (8 nm) and continuous doped silver (Ag) film was obtained by introducing a small amount of copper during the sputtering deposition of Ag and investigated as transparent EMI shielding components. The electromagnetic Ag shielding (EMAGS) film was realized in the form of conductive dielectric-metal-dielectric design to relieve the electro-optical trade-offs, which transmits 96.5% visible light relative to the substrate and shows an excellent average EMI shielding effectiveness (SE) of ∼26 dB, over a broad bandwidth of 32 GHz, covering the entire X, Ku, Ka, and K bands. EMI SE >30 dB was obtained by simply stacking two layers of EMAGS films together and can be further improved up to 50 dB by separating two layers with a quarter-wavelength space. The flexible EMAGS film shows a stable EMI shielding performance under repeated mechanical bending. In addition, large-area EMAGS films were demonstrated by a roll-to-roll sputtering system, proving the feasibility for mass production. The high-performance EMAGS film holds great potential for various applications in wearable electronics, healthcare devices, and electronic safety areas.