Phase Change Material-Based Film toward Enhanced Radiative Cooling and Mitigation of Overcooling

Daytime radiative cooling has generated an escalating level of interest as it offers zero-energy cooling even under strong solar illumination. However, two issues remain unresolved regarding the daytime radiative cooling. One is to further improve the cooling effect at high temperatures and the other is to suppress overcooling at low temperatures. Herein, we approached an effective design of a radiative cooling composite enhanced by a phase change material (PCM). The incorporation of the PCM increases the subambient cooling temperature of the composite by 2 °C under a solar intensity of ∼850 W m^–2, resulting in a final cooling effect of 6.8 °C, which demonstrates the synergistic enhancement of the radiative cooling in hot conditions. Furthermore, the incorporation of the PCM slows down the cooling rate of the composite when the temperature drops below the crystallization point, indicating a great potential to mitigate overcooling in cold environments. Additionally, the resulting composite exhibits excellent thermal and shape stabilities. Overall, the proposed PCM-enhanced radiative cooling composite demonstrates a significant advance toward the radiative cooling regulation, which holds promise for broadening its application in various practical environments.