Transparent Radiative Cooling Films Based on Dendritic Silica for Room Thermal Management

Abstract

Building energy consumption accounts for 40% of global energy use, with a large part attributed to windows. Transparent radiative cooling (TRC) coatings integrate transparency and radiative cooling, offering a promising solution. In this study, the transparency constraint and selective transmittance spectra of TRC films were proposed according to the heat transfer equation. On the basis of these rules, we designed a flexible TRC film composed of an emission layer, an ITO coating, a flexible substrate, and an adhesive layer from top to bottom. An ultrathin emission layer (~10 μm) with dendritic mesoporous silica nanoparticles embedded in polydimethylsiloxane was fabricated via a low-cost blade coating process suitable for manufacturing production. The film exhibited high visible light transmittance, ultraviolet blocking ability, and ultrahigh infrared emissivity. In addition, it provides benefits such as hydrophobicity and electromagnetic interference shielding. The results of outdoor tests revealed that a maximum cooling temperature of 12.6°C can be reached during sunny days. The theoretical cooling power reaches 99.25 W/m² at 27°C ambient temperature, making this TRC film a potential sustainable solution for room thermal management and energy efficiency.