Photonic Inverse Opal-Enabled Seamless Interface of Bilayer Structure for Color Regulation and Robust Passive Radiative Cooling.

Abstract

Colorful passive daytime radiative cooling has emerged as an attractive zero-energy-cooling technology that integrates aesthetic appeal with thermal management. However, achieving concurrent high cooling efficiency and mechanical robustness remains challenging, constrained either by the narrow solar reflection bandwidth and limited spectral tunability of monolayer photonic structures, or by interfacial heterogeneities in multilayer architectures. Here, we demonstrate a size-exclusion-assisted selective infiltration strategy for fabricating structurally colored daytime radiative cooling (SCDRC) sheets. A polymer phase exhibiting negligible solar absorption and high infrared emissivity permeates preassembled colloidal crystal templates, forming an ordered inverse opal layer upon etching, whereas microscale boron nitride platelets selectively excluded from the template organize into a packed solar-reflective microstructure. The resulting SCDRC sheets display tunable colors through pore geometry control, achieving >96% solar reflectance, >94% mid-infrared emissivity, a sub-ambient temperature reduction of 7°C in outdoor environments, and an average cooling power reduction of 20.7% across diverse climatic zones in China. The photonic framework demonstrates exceptional stability under prolonged thermal and humidity exposure, guaranteeing persistent coloration and cooling performance. This seamless-interface bilayer fabrication strategy establishes a viable platform for developing durable colored cooling materials integrating aesthetic appeal with energy-saving functionality, showing significant potential for advanced architectural and industrial applications.