Innovative Photon-Engineered Fluorescent Tri-Layer Polymeric Coatings for Sub-Ambient Colored Radiative Cooling

Colored radiative cooling (CRC) materials provide a sustainable solution to thermal management, mitigating global warming while maintaining aesthetic appeal. Nevertheless, conventional CRC materials exhibit reduced cooling efficiency due to their significant sunlight absorption and degraded optical performance in dusty outdoor environments. Developing self-cleaning CRC materials with high cooling performance and vibrant color remains challenging. Here, photon-engineered fluorescent tri-layer polymeric coatings (PFTPCs) is presented, which have an effective reflectance >100% at fluorescent emission wavelengths, yielding a historically high colored cooling capacity. By leveraging Purcell-enhanced fluorescent emission along with optimized photonic structures, the PFTPCs exhibit an effective solar reflectance of 94%, 96.3%, and 96.1% for red, yellow, and green colors, respectively. These coatings also demonstrate long-wave infrared emissivity surpassing 96%. Consequently, the PFTPCs achieve daytime sub-ambient cooling of 5.4-7.2 °C, outperforming commercial colored counterparts by 3.7-5.1 °C. Simulations indicate that when applied as roof and wall coatings, PFTPCs can significantly contribute to building energy savings across diverse climate zones. PFTPCs also exhibit excellent superhydrophobic properties, anti-fouling capability, and durability, providing strong resistance to ultraviolet irradiation, mechanical abrasion, rain, and soiling. This research paves the way for the rational design of high-performance fluorescence-assisted colored radiative cooling materials, promoting energy conservation and sustainability.