A group of German researchers have created a new metamaterial that is more transparent than glass, diffuses sunlight, adds privacy, is anti-reflective, self-cleaning, reduces glare, and increases radiative cooling. The new thin film is a polymer-based micro-photonic multi-functional metamaterial or PMMM, that can be applied onto a pane of glass. The impressive collection of properties are due to microstructures on the film’s surface, which are a pattern of pyramids, each 10 microns across.
The micro-pyramid structures scatter 73% of the incident light yet remarkably has a 95% transmittance, which is higher than glass (typically about 91%). The researchers claim the diffuse light is better for both people and plants.
Another valuable property is the metamaterial’s ability to let more infrared radiation exit a room that has a significant cooling effect on a room. Known as radiative cooling, the researchers showed the PMMM kept a room 10.8 degrees F cooler than the ambient air.
The micro-pyramid structures keep a thin layer of air below any water that hits the film. This makes the PMMM superhydrophobic, making dust, dirt and water roll right off. The superhydrophobic contact angle is 152 degrees.
The researchers see the best uses of the material are for transparent roofing for buildings, as well as greenhouses. The researchers calculate that the diffuse PMMM could improve the rate of photosynthesis in greenhouses by up to 9%. The full research paper can be found here.
Image: Nat Commun 15, 3798 (2024). https://doi.org/10.1038/s41467-024-48150-2m
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