A multi-state all-solid dynamic broadband photothermal window enabling decoupled multi-band thermal regulation

Smart windows that dynamically regulate solar irradiation and thermal radiation are critical for reducing building energy consumption, however, current systems suffer from intrinsic coupling between solar transmission and thermal emission, preventing independent regulation. Here, we report a multi-state all-solid dynamic broadband photothermal window that enables energy-flow decoupled regulation across visible, near-infrared, and long-wave infrared regions within a single integrated device. The Multi-State all-Solid Dynamic Broadband Photothermal Window (MSDBP) integrates a WO₃ electrochromic layer, a LiPON solid electrolyte, and an interpenetrated nanowire/nanosheet V₂O₅ ion-storage layer, forming a structure–material synergistic architecture with enhanced ion transport and carrier modulation. By integrating carrier-induced optical transitions with an asymmetric Fabry–Pérot cavity, the device establishes a spectrally selective thermal management mechanism, allowing independent and programmable control of solar transmission and thermal emission. Specifically, the MSDBP exhibits a large visible transmittance modulation (12.6–70.5% at 550 nm) and dynamically tunable infrared emissivity with Δε_{3–5 μm} = 0.44 and Δε_{8–14 μm} = 0.46, accompanied by a maximum temperature modulation of ~12.1 °C under controlled thermal conditions. Four adaptive operating modes (bright cool, bright warm, dark cool, and dark warm) are realized via voltage-driven regulation, enabling flexible responses to varying environmental conditions. This work demonstrates significant potential for reducing building energy consumption by enabling adaptive regulation of solar heat gain and thermal radiation, offering a practical strategy for next-generation energy-efficient building envelopes.