Flexible energy-saving surface for all-season adaptive thermal management

Solar heating (SH) and radiative cooling (RC) are effective methods for thermal management using solar energy and cold outer space, respectively. However, effectively integrating SH and RC to meet various seasonal demands poses a challenge due to the differing radiative properties needed for the material surfaces. In this work, we propose a flexible energy-saving surface (FESS) with the coupling effect of a resonant cavity and a photonic structure, which can synergistically control both near-infrared(NIR) and long-wave infrared(LIR). The resonant cavity in FESS is driven by a metal-insulator phase transition that exhibits different emissivity at high and low temperatures to regulate RC automatically. Simultaneously, the photonic structure achieves flexible control of NIR reflectivity within the range of 0.176-0.814 through its structure, enabling the on-demand modulation of the SH. As a result, the normal building integrating the FESS can cool low to 11.61 degrees C during warm weather (35 degrees C) and up to 18.95 degrees C during cold weather (0 degrees C), reducing thermal management energy consumption by 6.4 %- 43.5 % in various climatic regions worldwide. The presented FESS may be expected to be widely applied to the external surfaces of buildings, vehicles, or other shading structures, providing assistance for cooling/heating without energy consumption.