Suppressed-scattering windows for radiative cooling applications

TL;DR

This paper explores how material dispersion influences nanoparticle scattering, revealing suppressed-scattering windows that enable selective thermal emission for daylight radiative cooling, with potential applications in concrete materials.

Contribution

It demonstrates that material dispersion causes suppressed-scattering windows in nanoparticles, which can be tuned through co-design with host materials for improved radiative cooling.

Findings

Dispersive nanoparticles exhibit suppressed-scattering windows at infrared frequencies.

Suppressed-scattering windows are determined solely by material dispersion.

Co-design of nanoparticles and host materials enables tuning of cooling properties.

Abstract

The scattering of light by resonant nanoparticles is a key process for enhancing the solar reflectance in daylight radiative cooling. Here, we investigate the impact of material dispersion on the scattering performance of popular nanoparticles for radiative cooling applications. We show that, due to material dispersion, nanoparticles with a qualitatively similar response at visible frequencies exhibit fundamentally different scattering properties at infrared frequencies. It is found that dispersive nanoparticles exhibit suppressed-scattering windows, allowing for selective thermal emission within an highly reflective sample. The existence of suppressed-scattering windows solely depends on material dispersion, and they appear pinned to the same wavelength even in random composite materials and periodic metasurfaces. Finally, we investigate calcium-silicate-hydrate (CSH), the main phase of concrete, as an example of a dispersive host, illustrating that the co-design of nanoparticles and host allows for tuning of the suppressed-scattering windows. Our results indicate that controlled nanoporosities would enable concrete with daylight passive radiative cooling capabilities.