China : invented a window film that allows light and heat to pass selectively

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Chinese chemists have created a window film that selectively allows light and heat to pass through based on the voltage of the electrical current passing through it.

ACS Energy Letters magazine indicates that, according to the innovators, the membrane’s color, transparency, and level of thermal conductivity change within 1-2 seconds, but at the same time it maintains all its properties during at least 4,500 working cycles. It can therefore be used in the production of “smart” windows, flexible displays and other optical devices.

This membrane was created by a team of chemists led by Xu Hongbo at the Harbin Institute of Technology. The membrane is a transparent material consisting of so-called metal-organic frameworks (MOFs) - highly porous nanostructures of organic molecules and metal ions, similar in structure to honeycombs. It became clear to the researchers that metal-organic frameworks could be used to create so-called electrochemical coatings - materials whose optical properties and the nature of their interaction with infrared rays can be modified very flexibly using electrical pulses that change the structure of the organic molecules inside this material and the nature of their interactions with light particles.

It should be noted that chemists previously tried to adapt MOFs to create electrochromic coatings, but the materials they made changed their properties very slowly and had a very short lifespan. Now Chinese scientists have solved this problem by devising an approach that allows them to grow a layer of MOFs directly on the surface of ordinary glass coated with a layer of conductive tin oxide.