Self‐Adjusting Photothermal Heating for Multi‐State Photo‐Thermochromic Glazing

ABSTRACT

Photo‐ and thermochromic smart windows autoregulate solar light transmittance and heat gain without external power by directly responding to irradiance and temperature variations. However, they do not always adapt to visual and thermal comfort needs, often dependent on both sunlight intensity and ambient temperature. To address this challenge, multiresponsive photothermally‐assisted materials have been proposed, which convert sunlight into heat to trigger thermochromic transitions, though at expenses of permanent optical losses, residual coloration, and limited dynamic control. To surpass these limitations, here we report a switchable photo‐thermochromic glazing that integrates a light‐activated photothermal layer with a temperature‐driven scattering layer within a poly(vinyl alcohol)‐based architecture. Photochromic dyes confined in liquid nanodroplets enable rapid and reversible coloration as well as efficient photothermal conversion, while preserving a high transparent clear state. The generated heat activates a paraffin‐based thermochromism, inducing broadband light scattering. This hierarchical light–temperature coupling produces three adaptive optical states, achieving up to ∼60% solar transmittance modulation while maintaining high luminous transmittance (∼79%) in the clear state. As a result, the system simultaneously enhances visual comfort and suppresses solar heat gain, reducing indoor temperature rise (up to 41%) in a model house, thus providing a versatile approach for next‐generation smart glazing.