Optimization of a stacked multilayer for use in radiative cooling window

A radiative cooling window is a type of energy-saving windows which is designed to emit radiation in the infrared atmospheric transparency window, while reflecting near-infrared light and transmitting visible light. Several radiative cooling windows based on film structures have been proposed, but the transmissivity of visible light or the reflectivity of near-infrared light needs to be improved. In this paper, a radiative cooling window with stacked multilayer structure is proposed. The film thickness and period number of SiO₂/SiN periodic multilayer in the stacked structure are simultaneously optimized using genetic algorithm. Then the optimized stacked multilayer contain different periodic multilayer are also compared, and the spectral characteristic of the optimized stacked multilayer structure is further analyzed. An emissivity of 81% within the atmospheric window, a near-infrared reflectivity of 92% and a visible light transmissivity of 88% are obtained. Furthermore, the cooling performance of proposed stacked multilayer is studied, and a temperature drop of 32.2 K is realized when comparing it with a glass window with equal thickness. The proposed stacked multilayer structures could be used in radiative cooling windows for energy-saving of buildings and cars.