Efficient terahertz radiation absorption by dilute graphene composites

The interaction of terahertz electromagnetic radiation with dilute graphene-epoxy composites was studied experimentally at frequencies from 0.25 to 4 THz. Composites with low graphene loading (≤1.2 wt. %) below the electrical percolation threshold revealed the total shielding effectiveness above ∼70 dB (1 mm thickness) at 1.6 THz frequency. The unexpected high shielding effectiveness of dilute graphene composites in blocking terahertz radiation was mostly achieved by absorption rather than reflection. The shielding effectiveness increases with increasing frequency. Our results suggest that even the thin-film or spray coatings of the lightweight, electrically insulating graphene composites with thicknesses in the few-hundred-micrometer range can be sufficient for blocking terahertz radiation in many practical applications.