Free-standing Ti3C2Tx film with customizable impedance matching for absorptive electromagnetic shielding

Abstract

Flexible absorption-dominant electromagnetic interference (EMI) shielding materials are essential for sensitive electronic devices, such as those in telecommunications, the automotive industry, aerospace, and flexible electronics, owing to their lower reflection of electromagnetic waves, as well as their adaptability and lightweight. However, it is still a great challenge to achieve high absorption ability and wide bandwidth simultaneously, along with the flexibility to accommodate device deformation. In this study, flexible multilayer Ti₃C₂T_x (ML-Ti₃C₂T_x)/polytetrafluoroethylene (PTFE) composite films with adjustable EMI shielding ability were fabricated via a roll-to-roll method. The multiple loss mechanisms induced by the cavity structure of the ML-Ti₃C₂T_x microparticles and the “brick-mortar‭ network of the composite film provide more channels for multiple reflections and scattering of incident electromagnetic waves. In addition, the impedance matching could be customized by controlling the thickness of the film and the ratio of ML-Ti₃C₂T_x to achieve high absorption ability. As a result, a high EMI shielding effectiveness value of 70 dB in the X-band with only 0.0004% reflection is achieved by the 3.5-mm ML-Ti₃C₂T_x/PTFE-25 wt % film. Notably, benefiting from the strong interactions between the two components, the properties of the films remain constant even after deformation and extremely low-temperature (−200°C) treatment, indicating promising potential for future multiple applications.