Phase-Dependent Energy Dissipation for Dynamic Emissivity Modulation Using Quantum Dots Near Metallic Surfaces

Abstract

Recent advances in micro- and nanophotonic fabrication techniques have enabled precise control over thermal emissivity, unlocking a variety of intriguing applications. With self-adaptive features, dynamic tunability promises transformative potential but often depends on specialized materials with infrared optical properties responsive to external stimuli, limiting material choices and design flexibility. Herein, we introduce a new framework for dynamic emissivity modulation that exploits the phase-dependent energy dissipation, where the electromagnetic phase controls the amplitude of the total electric field and, consequently, the dissipation rate of the thermal emitter near metallic surfaces. Employing a bilayer system composed of Ag₂Se quantum dots (QDs) and a LiF spacer layer on a metallic substrate, we experimentally demonstrate a tunable range of spectral emissivity (Δϵ_λ) of ∼0.7 and a tunable range of total integrated emissivity in the 8–13 μm waveband (Δϵ) of ∼0.5. The theoretical result also suggests that a dynamic range of the total emissivity as large as 0.6 is feasible by replacing the spacer layer with thermal-responsive polymers, electroelastic materials, magnetoelastic materials, or other phase modulating layers. This design provides a versatile platform for integrating various stimuli-responsive materials to enable dynamically tunable thermal emissivity, paving the way for advanced applications in self-adaptive thermal management and smart thermal systems.