Photonic-Structure Colored Radiative Coolers for Daytime Subambient Cooling

Area of Science:

• Materials Science
• Sustainable Energy
• Optics

Background:

• Radiative cooling is a passive thermal management strategy that can reduce energy consumption.
• Current radiative cooling materials often have undesirable white or silver appearances, limiting their practical application.
• Developing colored radiative cooling materials is crucial for broader adoption in various scenarios.

Purpose of the Study:

• To develop flexible colored radiative cooling materials that maintain high solar reflectivity for effective cooling.
• To address the aesthetic limitations of existing radiative cooling technologies.
• To demonstrate subambient cooling performance of colored radiative coolers under direct sunlight.

Main Methods:

• Fabrication of flexible colored radiative coolers utilizing interferometric retroreflection-induced structural color.
• Characterization of the optical properties and cooling performance of the developed materials.
• Comparison of cooling performance against commercial paints under solar irradiation.

Main Results:

• The developed colored radiative coolers achieved subambient cooling of 4 K under sunlight exceeding 1000 W/m².
• These materials offer a colorful appearance while maintaining high solar reflectance, unlike conventional paints.
• The flexible, scalable, and low-cost nature of the material facilitates practical implementation.

Conclusions:

• A novel flexible colored radiative cooler based on structural color has been successfully developed.
• This technology resolves the conflict between aesthetic requirements and high solar reflection for radiative cooling.
• The colored radiative coolers show significant potential for replacing commercial paints in applications requiring both aesthetics and cooling, leading to reduced carbon emissions and energy consumption.