Electrically Tuning Electromagnetic Wave Shielding in Phase Engineered 1T/2H‐MoS ₂ ‐Based Devices

Controlling of electromagnetic wave absorption/reflection remains a significant technological challenge for stealth technology and protecting electronic devices operating in the gigahertz frequency range. Various materials can tune microwave reflection and absorption, thereby enabling adjustable electromagnetic interference (EMI) shielding; however, their multi‐millimeter thickness limits their applicability in integrated electronic systems. In this study, we present a method to modulate the reflection and absorption characteristics of incident electromagnetic waves using sub‐millimeter‐thick 1T/2H‐MoS 2 structures. We demonstrate an electric‐field‐driven EMI shielding mechanism for phase‐engineered MoS 2 based symmetric devices using PVA and KOH gel electrolyte. The coexistence of 1T and 2H phases provides a dynamic platform in which charge transport, interfacial polarization, and electromagnetic absorption–reflection mechanisms can be continuously regulated under external electric fields. Unlike conventional static EMI shielding approaches, our method enables active modulation capabilities that can dynamically adapt to demanding operational environments.