Reversed Yolk–Shell Dielectric Scatterers for Advanced Radiative Cooling

Abstract

AbstractPassive daytime radiative cooling dissipates heat from surfaces by reflecting sunlight and emitting infrared radiation to the cold outer space, featuring a zero‐energy consumption. Polymer‐dielectric radiative cooling coatings have received significant attention because of their scalable preparation, low cost, and ease of use. However, current dielectric scatterers reveal limited solar reflectance in the polymer‐dielectric coatings due to the optical crowding, which reduces cooling effect and hinders practical application. Employing a scalable emulsion templated method, reversed yolk–shell dielectric scatterers (RYSS) are developed to alleviate optical crowding effects in polymer‐dielectric coatings. This results in coatings with a solar reflectance of ≈97.4% and an infrared emittance of ≈96.9%, while achieving a substantial reduction in scatterers content. Besides, simulation results show that RYSS outperforms core–shell, hollow, and solid scatterers in enhancing solar reflectance. Using phase change materials as emulsion templates, RYSS with high heat storage effectively enhance daytime cooling and reduce nighttime over‐cooling. Moreover, cooling experiments on concentrating photovoltaics demonstrate a temperature drop of 42 °C (≈26.2 times extension of lifetime) and a notable 22% increase in open‐circuit voltage. This work suggests that RYSS presents a promising solution to overcome the challenges of radiative cooling materials and pave the way for their practical applications.