Solar cells operate by absorbing light first, then converting it into electricity. The most efficient cells needs to do this absorption within a very narrow region of the solar cell material. The narrower this region, the better the cell efficiency. The ability to strongly absorb light by these structures could pave the roadmap to higher cell efficiencies. Credit: University of Surrey
New ultra-thin, patterned graphene sheets will be essential in designing future technologies such as ‘smart wallpaper’ and internet-of-things applications Advanced Technology Institute uses moth-inspired ultrathin graphene sheets to capture light for use in energy production and to power smart sensors. Graphene is traditionally an excellent electronic material, but is inefficient for optical applications, absorbs only 2.3% of the light incident on it. A new technique enhances light absorption by 90%.
Graphene can now be manipulated to create the most light-absorbent material for its weight, to date. Using a technique known as nanotexturing, which involves growing graphene around a textured metallic surface, researchers from the University of Surrey’s Advanced Technology Institute took inspiration from nature to create ultra-thin graphene sheets with nano-patterning to localise light into the narrow spaces between the textured surface. This enhanced the amount of light absorbed by the material by about 90%.
“Moths’ eyes have microscopic patterning that allows them to see in the dimmest conditions. These work by channelling 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.”
Professor Silva commented: “Solar cells coated with this material would be able to harvest very dim light. Installed indoors, as part of future ‘smart wallpaper’ or ‘smart windows’, this material could generate electricity from waste light or heat, powering a numerous array of smart applications. New types of sensors and energy harvesters connected through the Internet of Things would also benefit from this type of coating.” It is now possible to observe strong light absorption from even nanometre-thin films…”our ultrathin coating of nanotextured few-layer graphene absorbs 95% of incident light across a broad spectrum, from the UV to the infrared.”
Prof. Silva noted: “The next step is to incorporate this material in a variety of existing and emerging technologies. We are very excited about the potential to exploit this material in existing optical devices for performance enhancement, whilst looking towards new applications. Through Surrey’s EPSRC funded Graphene Centre, we are looking for industry partners to exploit this technology and are keen to hear from innovative companies who we can explore the future applications of this technology with us.” The Surrey team developed this technology in cooperation with BAE Systems for infrared imaging in opto-MEMs devices.
http://phys.org/news/2016-02-unveils-graphene-moth-eyes-power.htmljCp
http://www.eurekalert.org/pub_releases/2016-02/uos-nru022316.php
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