Hierarchical MoS/Poly(ionic liquid) Metamaterials for Electrically Tunable Terahertz Stealth.

Active absorption modulation is critical for advanced stealth technologies, especially given the emerging detection threat from terahertz atmospheric windows. However, due to the difficulty in balancing high absorption and tunability, the actual manufacturing of most terahertz absorbers usually neglects the integration of electrical tuning, which limits their development of dynamic wave trapping for electronic countermeasure systems. Here, a terahertz stealth metamaterial (TSM) with hierarchical ionotronic architecture is proposed to overcome the tradeoff. Large-area continuous MoS assemblies tightly attached poly(ionic liquid) (PIL) microarrays provide enough conditions for surface electron conduction and plasmon mode excitation. By establishing wave-electron-ion interaction pathways, the directional migration of free anions inside the PIL and the accumulation of excess charge carriers up to 100.4% at the MoS interfaces are promoted, thereby stimulating changes in the plasma frequency of the absorption system. Consequently, this micro-nano structural design enhances the absorption tunability and combines multiple dissipative behaviors. TSM exhibit high specific attenuation (-275 dB mm), frequency agility (21.4%), and phase switching (153.1 deg.) within terahertz atmospheric windows. Moreover, the template-assisted assembly strategy adopted has the potential to be used for the building of universal blocks operating within other frequency ranges.