Vacancy‐Triggered Active Modulation on the Thermal Response of Interfacial Polarization Enables Highly Stable Broad‐Temperature Electromagnetic Wave Absorption

Abstract Maintaining stable electromagnetic wave absorption across wide temperature ranges hinges on utilizing the negative temperature response of interfacial polarization loss to compensate for increasing conductive loss at elevated temperatures. But the response amplitude is recognized as an uncontrollable parameter that passively relies on the temperature variation range, hindering the development of effective compensation. Herein, a strategy is proposed to actively amplify the temperature response amplitude of interfacial polarization through vacancy‐mediated thermal reconfiguration of interfacial charges. In SiC@ZnIn 2 S 4 heterostructures, controlled sulfur vacancy engineering enhances mobile interfacial charge density and thermal responsiveness, significantly enlarges interfacial charge density differentials before/after thermal excitation, achieving thermal response amplification of interfacial polarization. This active amplification mechanism achieves 93% compensation efficiency for excessive conductive loss during heating—a 65% improvement over passive systems. Consequently, optimized dynamic impedance matching maintains reflection loss below −10 dB in X‐band from room temperature to 300 °C. This work elucidates the mechanism of vacancy‐modulated interfacial charge dynamics via in situ characterization and multimodal calculations, while resolving the persistent challenge of temperature‐passive‐limited polarization response. The established paradigm of “vacancy‐triggered active modulation on the thermal response of interfacial polarization” provides a readily generalizable design framework for wide‐temperature electromagnetic functional materials.