Designing Mesoporous Photonic Structures for High-Performance Passive Daytime Radiative Cooling.

Area of Science:

• Materials Science
• Optics
• Thermodynamics

Background:

• Passive daytime radiative cooling (PDRC) offers a promising solution for electricity-free cooling.
• Porous polymers are ideal for PDRC due to their performance and scalability.
• Understanding the impact of pore properties on PDRC is crucial for material design.

Purpose of the Study:

• To investigate the relationship between pore properties and PDRC performance.
• To guide the design of high-performance porous coatings for PDRC.

Main Methods:

• Optical simulations were employed to study the effects of pore size, porosity, and thickness.
• Solar reflectance, thermal emittance, and net cooling power were simulated.

Main Results:

• Mixed nanopores (100 and 200 nm radii) achieved higher solar reflectance (0.951) compared to single-sized pores (0.811) at 300 μm thickness.
• An aluminum substrate enhanced performance, reaching a solar reflectance of 0.980 and thermal emittance of 0.984.
• Net cooling power reached 72 W/m² under semihumid conditions.

Conclusions:

• Pore structure significantly influences PDRC performance.
• Mixed nanopore designs are superior for maximizing solar reflectance.
• Simulation results provide a roadmap for developing efficient porous materials for PDRC.