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A Multi-State All-Solid Dynamic Broadband Photothermal Window Enabling Decoupled Multi-Band Thermal Regulation

Electrochromic smart window; Photothermal regulation; Infrared emissivity; Multi-band modulation; Radiative cooling

Smart windows that regulate solar irradiation and thermal radiation can reduce building energy use, but conventional systems couple solar transmission with thermal emission and cannot control them independently. Here, we report a multi-state all-solid dynamic broadband photothermal window (MSDBP) that integrates a WO3 electrochromic layer, a LiPON solid electrolyte, and an interpenetrated nanowire/nanosheet V2O5 ion-storage layer. Carrier-induced optical transitions and an asymmetric Fabry-Pérot cavity provide programmable control across the visible, near-infrared, and long-wave infrared regions.



The device switches between 12.6% and 70.5% transmittance at 550 nm and provides infrared-emissivity modulation of 0.44 in the 3-5 μm band and 0.46 in the 8-14 μm band. Four operating modes, including bright cool, bright warm, dark cool, and dark warm, combine daylighting, solar shading, radiative cooling, and thermal insulation. A maximum apparent-temperature modulation of approximately 12.1 °C was obtained under controlled heating. Outdoor testing further demonstrated a 3.4 °C reduction in the peak model-chamber temperature compared with commercial glass.



These results demonstrate that the MSDBP can independently and programmably regulate solar transmission and thermal emission, providing a practical strategy for adaptive thermal management and energy-efficient building envelopes.