Porous composite film embedded with garnet for daytime subambient radiative cooling

Passive radiative cooling is promising for global sustainable development due to its high energy efficiency, low emissions and non-pollution. Herein, a porous PVDF (polyvinylidene fluoride)-PMMA (polymethyl methacrylate) film with randomly distributed gadolinium gallium garnet (GGG) nanocrystals is developed by solvent volatilization-induced phase separation. The porous composite film exhibits a solar reflectance of 96.1 % and an atmospheric window emissivity of 0.952. Continuous outdoor test illustrates that the cooler owes ideal all-day sub-ambient cooling properties, with an average surface temperature 8.6 °C lower than the ambient temperature, a maximum temperature drop of 13.7 °C and a cooling power up to 81 W/m 2 . Besides, the cooler exhibits excellent flexibility, strength, and environmental stability. This work provides a new solution for achieving daytime sub-ambient radiative cooling and has the potential for a wide range of energy-saving applications.