EMI trap design of self-assembled monolayer and bilayer Ti₃C₂T_x MXene films: towards the application in microwave stealth optical window

This study presents a groundbreaking MXene/polyethylene terephthalate (Ti₃C₂T_x/PET) laminated “electromagnetic trap” structure based on an equal-impedance gradient design, which overcomes the reflection-dominated shielding mechanism of conventional transparent electromagnetic materials. By precisely controlling the number of Ti₃C₂T_x/PET layers (4–10 L), the PET dielectric thickness (∼3 mm), and the Ti₃C₂T_x film thickness (monolayer: ∼2.3 nm; bilayer: ∼3.7 nm), an absorption-dominant electromagnetic shielding performance was successfully obtained in the X-band. These structures exhibit exceptional tunability, delivering broadly adjustable average microwave absorption of 70% to 95% while maintaining a visible light transmittance between 17% and 66%. Remarkably, the 10-layer bilayer-Ti₃C₂T_x/PET trap achieved near-perfect maximum absorption (∼97%) along with an electromagnetic interference shielding effectiveness of up to 22 dB, significantly surpassing most reported transparent or semi‑transparent electromagnetic shielding structures. By establishing a comprehensive “design-fabrication-verification” framework, we elucidated the underlying microwave absorption mechanism, which is driven by the equal-impedance gradient effect and enhanced Ohmic losses induced by multi-interfacial wave reflections. This work not only provides an innovative material system and reliable design strategy for addressing electromagnetic stealth challenges in transparent windows, but also establishes a solid theoretical foundation for developing next-generation intelligent electromagnetic devices.