A thin, ultralight, and ultrabroadband (35–330 GHZ) electromagnetic wave absorber enabled by an impedance-graded nanofiber architecture

The rapid expansion of high-capacity wireless communication has increased the use of millimeter-wave (mmWave) and subterahertz (sub-THz) frequencies, leading to increasing concerns regarding electromagnetic interference (EMI). This concern has increased the demand for thin, lightweight, and broadband electromagnetic absorbers. In this paper, we report an ultralight, flexible absorber with a precisely engineered impedance-graded nanofiber architecture fabricated via a simultaneous electrospinning–electrospraying process. A porous poly(vinylidene fluoride-co-hexafluoropropylene) nanofiber matrix provides low permittivity for impedance matching with air, whereas spatially controlled deposition of multiwalled carbon nanotubes results in the generation of an optimized through-thickness conductivity gradient. The resulting 500-µm-thick absorber (with a relative thickness of 5.9% and a density of 0.23 g cm− 2) has an exceptional ultrabroadband absorption bandwidth of 35.6–330 GHz (an effective absorption bandwidth of 294.4 GHz and a fractional bandwidth of 161%). Modeling and experiments reveal that the graded conductivity profile effectively suppresses internal reflections, enabling unprecedented broadband absorption within a submillimeter thickness range. This work establishes a new material design paradigm that combines theoretical impedance optimization with scalable nanofiber-based fabrication, providing a practical method for next-generation EMI mitigation in advanced communication, sensing, and electronic systems operating in the mmWave and sub-THz regimes.