Silicon oxynitride multilayers as spectrally selective material for passive radiative cooling applications

Silicon oxynitride has optical properties that makes it attractive as radiative cooling material. Because of the interface contributions, multilayered configurations provide a very promising way to enhance the device performances. Three silicon oxynitride multilayers deposited onto aluminum-coated glass substrate were prepared and tested. A broadening of the absorption peak within the atmospheric window was observed. Radiative cooling parameters eS2H and νH were deduced from infrared reflection measurements. They correspond to temperature drops of 52, 48 and 56°C (from ambient temperature of 27°C), and cooling powers of 125, 118 and 119 Wm−2. Temperature drops and cooling power remain competitive for practical uses, even after non radiative exchange processes are taken into account.