Electromagnetic Interference Shields Based on Highly Crystalline Single-Walled Carbon Nanotubes

Although the convenience provided by electromagnetic waves used for information exchange is increasing, the energy of unwanted electromagnetic waves unintentionally emitted from devices is increasing as the devices work with higher frequency. In view of this vulnerability, thin films as lightweight electromagnetic wave shields against noise will be necessary for information protection. We propose the fabrication of lightweight electromagnetic wave shields using highly crystalline single-walled carbon nanotubes (HC-SWCNTs), which can be made large and flexible using a method based on a wet process, utilizing the optical and conductive properties of HC-SWCNTs. Electromagnetic wave shields are mainly classified into conductive, dielectric, and magnetic absorbers. We have developed a material synthesis technology for HC-SWCNTs and attempted to form an aqueous composite film using HC-SWCNTs and an organic binder. As a result, we found that the high crystallinity of CNTs suppresses the contact resistance between CNTs and we succeeded in constructing a flexible electromagnetic wave shielding film that can absorb electromagnetic waves in a wide bandwidth equivalent or superior to that of metal foil. This thin film can be applied to curved surfaces as desired because of its wet process, and it is expected to be a lightweight shield that can be used ubiquitously.