ABSTRACT
Advancements in nano/micro-technology for creating novel photonic metamaterials can enable ultrahigh performance surfaces or coatings that allow net-zero energy parity at thermodynamic equilibrium. This chapter covers metamaterials that demonstrate near-perfect, near-zero, and near-full contrast tuning of thermal radiative emission. We discuss the nature of ultrahigh reflection or transmission in High-Contrast Gratings for thermal insulation. Various phase transition oxide materials as thermochromic or electrochromic contrast switching emitters are comprehensively discussed. A background of the working principles of optical interference and resonance is presented. With the combination and refinement of both gratings and phase transition oxide-bearing metamaterials, we can obtain passive and switchable daytime radiative coolers. This capability can lead to a carbon-neutral society using less demanding and complex thermal management systems.
