Sunlight‐Driven Photo‐Thermochromic Smart Windows

Smart windows have been paid much attention in recent years since they can save more energy in comparison with ordinary counterparts. However, exterior heating or electric system is still required to stimulate the color/transparency responses for current smart windows, which increases the complexity of device's structure and still consumes energy. Thus, sunlight‐responsive smart windows in building are particularly appealing for saving energy but seldom reported. Herein, we propose a facile and low‐cost method to construct reversible color/transparency switching materials by integrating the unique photothermal conversion feature of noble metal nanoparticles with thermochromic compounds. The switching behavior of thermochromic materials is not triggered by traditional exterior heating but laser/sunlight irradiation. In particular, we achieve ambient sunlight‐driven photo‐thermochromic smart windows (PTCSWs) prototype which can automatically become opaque to block sunlight on scorching days and return to a transparent state under low lighting condition. We believe that this work will pave a way for a novel class of smart windows which is highly expected to be integrated into building components to tailor specific camouflage coating and substantially save energy.