Heterostructured Fe@C/polythiophene metamaterials for compatible ultra-broadband microwave absorption and low infrared emissivity

Achieving spectral compatibility between microwave absorption (MA) and low infrared emissivity presents a formidable challenge due to the conflicting electromagnetic requirements of different bands. Herein, we engineered a gradient metamaterial utilizing heterostructured Fe@C/polythiophene composites, fabricated via integrated three-dimensional (3D) printing for achieving compatible ultra-broadband MA and low infrared emissivity. Corroborated by both experimental measurements and numerical simulations, the resulting metamaterial exhibits exceptional MA performance, achieving an ultra-broadband effective absorption bandwidth of 12.5 GHz that fully encompasses the C, X, and Ku bands. Crucially, the introduction of polythiophene further regulates the surface conductance, yielding low infrared emissivities of 0.67 (3–5 μm) and 0.48 (8–12 μm) in key atmospheric windows. The dual-functionality is attributed to the synergistic optimization of composition and structure, where the gradient architecture and heterogeneous interfaces maximize MA attenuation via impedance matching and polarization relaxation, while the regulated surface conductivity via polythiophene effectively inhibits infrared radiation. This study establishes a versatile micro-nano structural paradigm for developing high-performance metamaterials capable of countering multispectral detection.