Modulating electromagnetic response through the regulation of built-in electric fields

The construction of built-in electric fields (BIEF) in heterogeneous structures represents an effective approach for optimizing the electromagnetic (EM) parameters of composite materials. However, effectively regulating the BIEF intensity within the material matrix to better address the issues of dielectric constant frequency dependence and impedance mismatch remains a significant challenge. In this manuscript, a novel material Co@N-TiO₂/TiN (Co@NTT), which utilizes doping to regulate the strength of the BIEF is meticulously fabricated. Both experimental and theoretical results confirm the interface charge redistribution induced by the strong BIEF, which not only effectively modulates the EM parameters but also subtly optimizes impedance matching. It exhibits good absorption capability across multiple frequency bands, with a minimum reflection loss of −62.2 dB in the C band and −67.4 dB in the Ku band. This work paves the way for the development of functional materials with tailored EM properties through space charge engineering.