Flexible, lightweight and multi-level superimposed titanium carbide films for enhanced electromagnetic interference shielding

The progressive development of next-generation flexible and portable electronics highly requires electromagnetic interference (EMI) shielding layers with a trade-off among high shielding effectiveness (SE), lightweight and flexible nature. Herein, a multiscale layered structure optimization strategy is proposed to enhance EMI shielding performance through orderly superimposing individual free-standing Ti3C2 (F-Ti3C2) film with an ultrathin thickness of similar to 4 mu m. Compared to a bulk F-Ti3C2 film (64.6 dB) with the same weight of 150 mg, the multi-level superimposed Ti3C2 films with six individual layers (S-Ti3C2-6) show much higher EMI shielding performance (84.7 dB). Furthermore, the increment in the gap distance between the adjacent F-Ti3C2 films can also increase the EMI SE from 51.1 dB (d = 0 mm) to 74.9 dB (d = 1.5 mm). The underlying mechanism can be attributed to the synergistic effect of multiple internal reflections between Ti3C2 nanosheets and multiple-wave interference between adjacent F-Ti3C2 films. Furthermore, the multi-layered design strategy can be extended to other EMI materials including polypyrrole and graphite, etc. The demonstration of Ti3C2 coatings to block EM waves proves their considerable advantages over commercial shielding packages. This work provides a novel methodology to design EMI shielding layers for the practical applications.