Scalable dual-layer film with broadband infrared emission for sub-ambient daytime radiative cooling

Abstract As a passive cooling method with no energy input, radiative cooling has great potential in applications like building energy saving. The key to effective radiative cooling lies in selectively controlling the radiative properties in both solar and mid-infrared spectrums, and simple structures based on polymer materials attract growing attentions due to their overwhelming advantages of low cost and large-scalable fabrication. In this study, a dual-layer film consisting of polyvinyl fluoride (PVF) layer and Ag coating is proposed to act as an efficient daytime radiative cooler with low solar absorption and broadband infrared emission. An outdoor test demonstrates that sub-ambient daytime cooling is successfully achieved by the proposed cooler with an equilibrium temperature 2 °C below the ambient under solar irradiation of 950 W/m2. Due to better durability and better performance in anti-staining and corrosion protection than other polymer materials, the demonstrated cooling performance based on the PVF film would facilitate radiative cooling principle in much broader applications.