Electrochemically Mediated Interfacial Charge Polarization in Heterostructured Flexible Films for Dynamic...

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⁺-induced electron-interface cooperative regulation by constructing an ultrathin acetylene black/H_xWO₃ (AB/H_xWO₃) heterostructure film device for real-time electromagnetic wave modulation. Specifically, the controllable transformation of H_xWO₃ from the initial monoclinic phase to the tetragonal phase and eventually to the cubic phase driven by H⁺ insertion triggers the valence state evolution from W⁶⁺ to W⁴⁺ 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_R: 3.7 to 6.0 dB). Meanwhile, the introduction of AB leads to the reconstruction of the energy band structure during the protonation of WO₃, inducing strong polarization domains and a mass of dipoles at the AB/H_xWO₃ heterointerface, which significantly enhances the polarization loss capacity and thereby promotes significant modulation in EMWs absorption shielding efficiency (SE_A: 9.9 to 18.0 dB). Based on the above electron density and interface polarization synergistic enhancement mechanism, the AB/H_xWO₃ 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_T) of 130 dB mm^-1, significantly outperforming previous reports. These findings underscore the great potential of this lightweight, ultrathin device for integrated electronics and adaptive electromagnetic environment applications.