Multispectral Synergistic Electrochromic Regulator With Triple Atmospheric Windows Selectivity for Global Building Energy Saving.

Abstract

As a growing contributor to global energy demand, building energy consumption is strongly constrained by the passive nature of conventional opaque building envelopes. Here, we design a tunable multispectral regulator based on an ITO/WO₃/LiNbO₃/NiO/ITO electrochromic all-thin-film stack. Through the ingenious device architecture of an asymmetric Fabry-Pérot cavity (F-P cavity), the regulator achieves multispectral positive synergistic modulation: in the cooling mode, it simultaneously reflects sunlight and exhibits selective high emissivity within the atmospheric windows; in the heating mode, it absorbs sunlight while maintaining low infrared emissivity. This design also extends effective modulation to the third atmospheric window (16-25 µm). Consequently, the device delivers synergistic and wide modulation with values of 0.52 and 0.64 in the solar (0.3-2.5 µm) and mid‑far infrared (2.5-25 µm) bands, respectively, enabling both summer cooling and winter heating. Outdoor testing in an arid desert climate validates effective thermal regulation, achieving a diurnal temperature difference of ∼5.5°C. With its adaptive regulation capability, the device is well-suited for year‑round building energy saving. EnergyPlus simulations further reveal substantial annual energy savings, particularly for heating in cold regions (22.2 MJ/m²). This work provides a monolithic tunable platform for synchronized multispectra regulation, paving the way for next‑generation intelligent thermal management systems.