Self-Cleaning Red-Toned Perylene Poly(aryl ether) Film with Superior NIR Reflectance for Passive Radiative Cooling

Radiative cooling provides a low-energy consumption remedy for the urban heat island effect. However, most radiative cooling materials use light-colored surfaces to achieve higher reflectivity, which not only causes light pollution problems but also degrades performance after surface contamination. Here, we through the design of the polymer structure used perylene diimide with coloration ability to prepare the crimson polymer perylene poly(aryl ether) (P-FAPE) by simple condensation reaction and prepared the superhydrophobic film with a porous structure by the method of nonsolvent-induced phase transformation. The polymer film has high near-infrared reflectance, with a maximum reflectance of 93% in the near-infrared region and emissivity reaches 95–98% in the atmospheric transmission window. In three days of outdoor testing, the P-FAPE6 film showed an average temperature drop of 5.72–8.52 °C compared to ambient temperature. Importantly, the water contact angle of the P-FAPE6 film is 160°, and the self-cleaning effect prevents the film surface from dirt contamination or wetting in long-term outdoor use. The P-FAPE6 film also demonstrated long-term stability, a V-0 rating for fire resistance in the UL-94 combustion test, which is promising in applications for cooling building facades, outdoor tents, and vehicle sunshades.