New research has demonstrated how graphene can be manipulated to create the most light-absorbent material for its weight. This nanometer-thin material could enable applications such as "smart" wallpaper that generates electricity from waste light or heat to power a host of applications of the Internet of Things.

Just one atom thick, graphene is very strong and has great electrical conductivity, but traditionally it has proven inefficient at light absorption. Researchers led by Professor Ravi Silva, from the University of Surrey’s Advanced Technology Institute (ATI), understood that for graphene’s potential to be realized as material for future applications, it should also harness light (and heat) effectively.

Using a technique known as nanotexturing, which involves growing graphene around a textured metallic surface, the researchers took inspiration from nature to create ultra-thin graphene sheets designed to more effectively capture light. The team used the nano-patterning to localize light into the narrow spaces within the textured surface, enhancing the amount of light absorbed by the material by about 90%.

Researchers boosted graphene's light-absorption capacity by about 90%. Image credit: University of Surrey.Researchers boosted graphene's light-absorption capacity by about 90%. Image credit: University of Surrey. “Moths’ eyes have microscopic patterning that allows them to see in the dimmest conditions," Professor Silva notes. "These work by channeling light towards the middle of the eye, with the added benefit of eliminating reflections, which would otherwise alert predators of their location. We have used the same technique to make an amazingly thin, efficient, light-absorbent material by patterning graphene in a similar fashion.”

Solar cells coated with this material would be able to harvest very dim light, Silva says. Moreover, installed indoors as part of a smart window or wallpaper application, the material could generate electricity from waste light or heat, potentially powering a wide array of smart applications.

"Typically a graphene sheet would have 2-3% light absorption," says fellow ATI researcher Dr. José Anguita. "Using this method, our ultrathin coating of nanotextured few-layer graphene absorbs 95% of incident light across a broad spectrum, from the UV to the infrared.”

The researchers' next step is to incorporate the material into a variety of existing and emerging technologies. Through Surrey’s Graphene Centre, they are now looking for industry partners to help commercialize the technology.

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