Realization of an efficient radiative cooling emitter with double layer inorganic SiO2 and TiO2 metamaterial

A novel double-layer thermal emitter consisting of inorganic SiO2 and TiO2 metamaterials is proposed and numerically investigated. It can achieve ultrahigh absorption of 96.42 % and 92.97 % in the first and second atmospheric transparency window simultaneously, which helps to achieve efficient radiative cooling. On the premise of obtaining high absorption, a comparative study on the design with and without the metal substrate has been conducted, verifying our simple design can be adopted without the metal substrate. Meanwhile, the high emissivity still persists under different incident angles, air mass and water vapor column. Under the influence of convection coefficients, a net cooling power of 164.39 W/m2 is achieved. Finally, we establish a steady heat balance system to mimic the thermal emitter and obtain an average temperature drop of 9.6℃ with the Jacobian iteration method. Therefore, our design with excellent cooling capacity may provide a new guidance in the application of radiative cooling device.