Dual-type heterogeneous interface design enables customized tuning of dielectric parameters of multifunctional, lightweight, flexible absorbers for broadband electromagnetic wave absorption

With the boom in 5 G technology comes widespread concern about electromagnetic (EM) interference and the safe use of electronics. Conventional electromagnetic wave (EMW) absorbing materials in the form of coatings are often inflexible and poorly adapted to different EM environments. Diversified application scenarios require EMW absorbing materials with a wide absorption band and multifunctional properties. Herein, the frequency dispersion (FD) requirements of the EM parameters of the broadband absorber in different frequency bands are determined by EM simulation. Based on the dominant role of interface polarization on FD, we designed different types of heterogeneous interfaces to meet the needs of strong FD in the low-frequency band and weak FD in the high-frequency band. Through the optimized design of heterogeneous interfaces, CC@ZnO/ZnS composites exhibit excellent EMW absorption performance, achieving flexible, ultrathin (2.1 mm), ultralight (10 wt%), and broadband (7.02 GHz), which is superior to EMW absorbing materials of similar compositions. In addition, the composites have good piezoelectric/inverse piezoelectric properties, which can convert EM energy into mechanical energy while absorbing EMW, thus realizing applications in multifunctional fields such as sensors, controllers and energy converters. More noteworthy is the sample's highly efficient thermal insulation, flame retardant and anti-frosting properties, demonstrating important advantages for service in harsh environments. Therefore, CC@ZnO/ZnS composites not only have good practical application characteristics while realizing broadband absorption, but also are expected to achieve multifunctional applications in different fields.