Far-field radiative thermal rectifier based on nanostructures with vanadium dioxide

Radiative thermal rectifiers capable of realizing asymmetric heat flux transfer have attracted a lot of research interests recently, mainly focusing on the engineering of the emissivity spectra. In this Letter, we propose a far-field radiative thermal rectifier utilizing the phase change material vanadium dioxide (VO2). The thermal rectifier consists of a metamaterial infrared absorber and a two-layer thin-film structure acting as the active and the passive components, respectively. Numerical optimization has been carried out to control the emissivity spectra of both parts and maximize the overall rectification effect. A large thermal rectification factor of 3.5 is predicted at a temperature bias of ΔT=100 K.