Daytime Radiative Cooling Sheet Functionalized by Al₂O₃-Assisted Organic Composite.

Area of Science:

• Materials Science
• Nanotechnology
• Sustainable Energy

Background:

• Daytime radiative cooling is an efficient, eco-friendly technology.
• Focus is expanding from cooling capacity to practical applications.
• Organic materials offer promising, versatile platforms for radiative cooling.

Purpose of the Study:

• Introduce a high-performance daytime radiative cooler in a flexible sheet format.
• Utilize emerging organic materials for enhanced radiative cooling.
• Investigate the performance of an aluminum oxide-assisted organic composite (AOC) for cooling.

Main Methods:

• Fabrication of an aluminum oxide-assisted organic composite (AOC) sheet using electrospinning and hot-pressing.
• Characterization of optical properties: solar reflectance and atmospheric transparency window emissivity.
• Evaluation of cooling performance through direct measurement and application testing.

Main Results:

• The AOC sheet exhibits high solar reflectance (97.9%) and high emissivity (95.2%) in the 8-13 µm atmospheric transparency window.
• Calculated cooling power reached 120.1 Wm⁻².
• Experimental tests showed a 4.9°C sub-ambient temperature reduction and a 12.7°C reduction in a car model's interior.

Conclusions:

• The developed AOC sheet demonstrates exceptional daytime radiative cooling performance.
• The material's flexibility and high performance indicate significant potential for practical cooling applications.
• This technology offers a sustainable solution for passive cooling challenges.