Highly tunable thermal emitter with vanadium dioxide metamaterials for radiative cooling.

ABSTRACT

An efficient thermal emitter for selective radiative cooling is realized with vanadium dioxide metamaterials. The novel structure consists of patterned VO2 metamaterials on the multilayer substrate and a composite layer on it. To obtain the enhanced emissivity, the influence of the top composite layer and external thermal stimuli are comprehensively optimized. The emissivity can reach up to 0.952 in the metallic phase of VO2 with a composite layer in the atmospheric window, which is due to strong localization of the electric field in the cavity. The influence on the emissivity with different incident angles and geometric parameters is investigated elaborately. Finally, the cooling power is calculated and achieves a high value of 710W/m2 at 383 K, which is significantly higher than that of previous works. Thus, our proposed tunable emitter with high performance will be beneficial to the dynamic radiative cooling system and may open a potential application in building cooling and intelligent windows.