Electrochemically Mediated Interfacial Charge Polarization in Heterostructured Flexible Films for Dynamic Electromagnetism Regulation.
basic_science · Level V
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- Record sourced from PubMed, PMID 42252860.
- Also identified by DOI 10.1002/adma.202523231.
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Abstract
Tunable electromagnetic waves (EMWs) response and dynamic regulation play a critical role in fields such as radar and satellite communication, ranging from radiation protection to signal compatibility. However, the modulation capability and thin-film development of current electromagnetic materials are limited in the integration development in an effective dynamic electromagnetic environment, owing to their conductivity-dominated single response mechanism. Unlike the previously reported conductivity-dominant mechanism, this work proposes a design strategy based on H<sup>+</sup>-induced electron-interface cooperative regulation by constructing an ultrathin acetylene black/H<sub>x</sub>WO<sub>3</sub> (AB/H<sub>x</sub>WO<sub>3</sub>) heterostructure film device for real-time electromagnetic wave modulation. Specifically, the controllable transformation of H<sub>x</sub>WO<sub>3</sub> from the initial monoclinic phase to the tetragonal phase and eventually to the cubic phase driven by H<sup>+</sup> insertion triggers the valence state evolution from W<sup>6+</sup> to W<sup>4+</sup> and the reduction of the work function, which significantly enhances the n-type doping effect and promoting the increase in free electron density, thereby achieving tunable EMWs reflective shielding efficiency (SE<sub>R</sub>: 3.7 to 6.0 dB). Meanwhile, the introduction of AB leads to the reconstruction of the energy band structure during the protonation of WO<sub>3</sub>, inducing strong polarization domains and a mass of dipoles at the AB/H<sub>x</sub>WO<sub>3</sub> heterointerface, which significantly enhances the polarization loss capacity and thereby promotes significant modulation in EMWs absorption shielding efficiency (SE<sub>A</sub>: 9.9 to 18.0 dB). Based on the above electron density and interface polarization synergistic enhancement mechanism, the AB/H<sub>x</sub>WO<sub>3</sub> electrode with a thickness of only 80.16 µm achieves significant modulation of the total shielding efficiency from 13.6 to 24.0 dB in X-band and obtains an exceptionally large thickness-normalized specific shielding efficiency (ΔSSE<sub>T</sub>) of 130 dB mm<sup>-1</sup>, significantly outperforming previous reports. These findings underscore the great potential of this lightweight, ultrathin device for integrated electronics and adaptive electromagnetic environment applications.