Ultrahigh Visible-Transparency, Submicrometer, and Polymer-Free Radiative Cooling Meta-Glass Coating for Building Energy Saving

Glass windows are the most energy-inefficient part of buildings, which triggers the ongoing chasing of energy-efficient transparent radiative cooling (TRC) metamaterials on glasses that simultaneously maintain high visible (VIS) transparency, block near-infrared (NIR) solar radiation, and emit thermal energy through the atmosphere window (AW). However, the stringent multispectral regulation remains challenging since it involves with huge parameter spaces and significant interactions among different bands. Additionally, most TRC metamaterials require a top ∼50 μm polymer for high emissivity in the AW, which will reduce the VIS transparency and suffer from aging issue. Here, we employ the deep reinforcement learning (DRL) method, leveraging its robust material screening and structure optimization capabilities, to design a five-layer submicrometer dielectric multilayer, composed of two stacked materials, as polymer-free TRC metamaterial on glass or meta-glass for short. Utilizing a plain glass substrate with high emission in the AW, our meta-glass demonstrates an ultrahigh angular-independent (