Patterning of SiO2 interfaces for radiative cooling applications

Abstract

Silicon dioxide (SiO2) is a prominent material for radiative cooling applications due to its negligible absorption at solar wavelengths (0.25-2.5 µm) and exceptional stability. However, at thermal infrared wavelengths, its bulk phonon-polariton band introduces a strong reflection peak inside the atmospheric transparency window (8-13 µm) which is detrimental to its selective emissivity. Herein, we demonstrate scalable strategies for the patterning of ordered and disordered SiO2 metasurfaces enhancing their thermal emissivity and enabling sub-ambient passive cooling under direct sunlight.