Symmetric and Asymmetric Fabry–Pérot Cavity Design for a Dual-Mode Thermal Management Photonic Film with High-Purity Color

Radiative thermal management (RTM) is a sustainable and environmentally friendly strategy because it needs no external energy input and can reduce greenhouse gas emissions and thus recently has gained significant attention. However, the material color in existing radiative cooling/heating applications is traditionally white/black in order to maximize cooling/heating performance, which limits their practical application range. Herein, we propose a symmetric and asymmetric Fabry–Pérot cavity structure to fabricate a polymer-based photonic dual-mode thermal management film with a high-purity structural color display. The film can be adjusted as needed to produce a colored appearance with different hues while simultaneously maintaining sufficient radiative cooling power. The cooling side of the color dual-mode photon film exhibits high solar reflectivity (92.1%) and infrared emissivity (96.0%). Therefore, the maximum radiative cooling effect in the daytime subenvironment reaches 5.8 °C, and the maximum theoretical cooling power is high up to 62.6 W/m2. Meanwhile, the heating side of the dual-mode film features a very low infrared emissivity (8.2%) and a high solar absorption rate (61.5%), and its radiative heating capacity reaches 61.1 °C. Compared with traditional coatings, the colored dual-mode film can save up to 10.3% of annual energy in the northern and southern temperate zones. The color dual-mode photon film can easily switch between cooling and heating modes by flipping to adapt to dynamic cooling and heating scenarios, which is of great significance for alleviating the greenhouse effect and promoting sustainable development.