Thermal metadevices for dynamic switching between narrowband and broadband thermal emission based on reversible metal electrodeposition

Abstract

To dynamically tune the thermal radiation spectrum is critical to applications like radiative cooling, thermal camouflage, and thermophotovoltaics. However, it is currently difficult to achieve a dynamic switch between broadband and narrowband thermal emission states in a single device. Here, we propose a dynamically tunable thermal metadevice based on the combination of metasurface design and the reversible metal electrodeposition technology to fill this gap. This metadevice is based on the metal–insulator–metal (MIM) metasurface structure with the bottom metallic layer capable of being dynamically deposited and dissolved via the reversible electrodeposition process. In this way, the magnetic polaritons excited in the MIM metasurface, which lead to near-perfect narrowband thermal emission, can be dynamically switched on and off. Since the organic electrolyte in the metadevice is highly emissive in the entire infrared spectrum, when the bottom metallic layer is fully stripped, the entire device exhibits a broadband thermal emission behavior. As a consequence, the metadevice can be flexibly switched between broadband and narrowband thermal emission states. We further show that by tuning the structural parameters of the metasurface, the resonance wavelength of the narrowband thermal emission can be tuned from 2 to 5 μm. Additionally, we investigate the effect of an additional thin layer of Pt used to mitigate the lattice mismatch between Ag and BaF2 glass in practice. We envisage the proposed design can offer new opportunities for dynamically switchable thermal radiation devices.