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

Passive daytime radiative cooling (PDRC) has drawn significant attention recently for electricity-free cooling. Porous polymers are attractive for PDRC since they have excellent performance and scalability. A fundamental question remaining is how PDRC performance depends on pore properties (e.g., radius, porosity), which is critical to guiding future structure designs. In this work, optical simulations are carried out to answer this question, and effects of pore size, porosity, and thickness are studied. We find that mixed nanopores (e.g., radii of 100 and 200 nm) have a much higher solar reflectance (R) over bar (solar) (0.951) than the single-sized pores (0.811) at a thickness of 300 mu m. With an AI substrate underneath, (R) over bar (solar), thermal emittance (epsilon) over bar (LWIR), and net cooling power P-cool reach 0.980, 0.984, and 72 W/m(2), respectively, under a semihumid atmospheric condition. These simulation results provide a guide for designing high-performance porous coating for PDRC applications.

Automated summary

Passive daytime radiative cooling (PDRC) is gaining attention for its ability to cool without electricity. Porous polymers are attractive due to their excellent performance and scalability. This study explores how PDRC performance is affected by pore properties, such as size and porosity, through optical simulations. The results show that mixed nanopores have higher solar reflectance than single-sized pores, and under a semi-humid atmospheric condition, using an AI substrate can significantly increase thermal emittance and net cooling power. These findings provide guidance for designing high-performance porous coatings for PDRC applications.