Sunlight‐Driven Photo‐Thermochromic Smart Windows (Solar RRL 4∕2018)

The development of smart windows is of great interest for reducing energy consumption, because residential and commercial buildings account for about 40% of total energy consumption. Recently, Prof. Cheng's group constructed a sunlight-driven photo-thermochromic smart windows (PTCSWs) prototype which can automatically become opaque to block sunlight and heat on scorching days and return to a transparent state under low lighting condition. Here (see article number 1700219), hydroxypropyl methylcellulose (HPMC) and gold nanocrystals mixture were mixed inside the sealed glasses. HPMC in the aqueous solution state is transparent at room temperature. Raised temperature will lead to the opaque state of HPMC. Gold nanocrystals mixture as local heating source can convert sunlight irradiation into heat, thereby driving the transparent–opaque transition of HPMC. Especially, the switching temperature and colors are tailorable which is highly expected to be integrated into building components to tailor specific camouflage coating and save energy substantially or into temperature-alarm systems.