High‐Performance Photonic Films with Enhanced Thermal Conductivity and High‐Temperature Stability for Radiative Cooling

Abstract Radiative cooling constitutes an energy‐efficient passive cooling technology with significant future potential, achieving spontaneous temperature reduction without energy input through solar reflection and thermal radiation to outer space. While current radiative cooling materials predominantly serve ambient temperature applications (e.g., personal thermal management, building energy efficiency), practical demands often involve high‐temperature scenarios such as automotive engines (80–120 °C), thermal‐intensive base stations (70–80 °C), and large‐scale chemical facilities (150–200 °C). Materials for these applications require exceptional thermal stability, superior radiative cooling performance, and enhanced thermal conductivity. This study presents a high‐temperature resistant radiative cooling film with optimized thermal transport properties, achieved through the integration of 2D hexagonal boron nitride (h‐BN) dielectric nanosheets into a melt‐processable perfluoroalkoxy (PFA) polymer matrix. The experimental findings demonstrate that the photonic film exhibits not only durability at 200 °C over an extended period, but also exhibits favorable thermal conductivity, thereby facilitating the dissipation of heat from high‐temperature devices. Furthermore, it exhibits 97.36% reflectance in the solar band and 86% mid‐infrared emissivity. When exposed to 8000 W m −2 heating, the film achieves a temperature reduction of up to 30 °C. This photon‐engineered architecture provides innovative solutions for thermal management in high‐temperature environments.