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Updated: Sep 10, 2025
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Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition
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Self-Stratifying Colored Radiative Cooling Paints Through Narrow-Band Color Preservation Scheme
Dudong Feng1, Andrew S Witty1, Fletcher I Birnbaum1
1School of Mechanical Engineering and the Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA.
Advanced Materials (Deerfield Beach, Fla.)
|August 20, 2025
Summary
This study introduces a novel self-stratifying paint for colored passive daytime radiative cooling. The paint achieves vibrant colors and efficient cooling, overcoming previous scalability challenges.
Area of Science:
- Materials Science
- Nanotechnology
- Thermodynamics
Background:
- Passive daytime radiative cooling (PDRC) offers significant energy-saving potential.
- Current PDRC technologies often rely on white or reflective surfaces, limiting aesthetic and functional applications.
- Achieving colored PDRC surfaces faces scalability challenges in processing.
Purpose of the Study:
- To develop a novel, general, and scalable self-stratifying approach for creating colored radiative cooling paints.
- To demonstrate the feasibility of producing various colors with efficient cooling performance.
- To address the trade-off between color and cooling performance in PDRC materials.
Main Methods:
- A self-stratifying paint formulation utilizing narrow-band absorption dyes.
- Single-coat application leading to spontaneous formation of an absorption-scattering dual-layer structure.
- Characterization of optical properties (solar reflectance, emissivity), cooling performance, and mechanical properties (abrasion, adhesion, contact angle).
Main Results:
- Demonstrated cyan, magenta, and yellow paints achieving 93% solar reflectance and 0.94 sky window emissivity for subambient cooling.
- Developed a black paint with 46.3% solar reflectance and a 25°C temperature drop.
- Purple paint showcased color customization within the CMYK space.
- Mechanical and surface properties matched or exceeded commercial products.
Conclusions:
- The self-stratifying paint approach enables efficient colored passive daytime radiative cooling with enhanced properties.
- This method overcomes scalability limitations and offers a pathway for diverse applications.
- The findings provide insights for developing advanced paints for cooling and water harvesting.
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