Researchers Discover New Potential in Light Harvesting, Optoelectronics

Engineers have been working with nanotechnology in a variety of ways to improve light harvesting in solar applications. Researchers at the University of Buffalo invented a nanocavity to improve the design of ultrathin solar panels, video cameras, and other optoelectronic devices. Now engineers in Australia say they have discovered a mechanism that could allow for the design of new composite materials for light harvesting and optoelectronics.

The team at Griffith University, led by Qin Lin, associate professor in the Environmental Engineering and Queensland Micro- and Nanotechnology Center, made their discovery by experimenting with titania and graphene quantum dots.

The team has for the first time found a quantum-confined bandgap narrowing mechanism where ultra-violet (UV) absorption of the graphene quantum dots and titania nanoparticles can be extended into the visible light range, researchers said. This mechanism could allow for the design of a new class of composite materials for light harvesting and optoelectronics, Li said.

Engineers in Australia have discovered a mechanism that could allow for the design of new composite materials for light harvesting and optoelectronics, they said. The discovery could lead to a coating that could make solar panels ultra-efficient by allowing them to harvest visible light as well as UV. It also has applications for optoelectronics, researchers said.
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“Wherever there is abundant sun we can brush on this nanomaterial to harvest solar energy to create clean water,” she said. According to Li, practical applications for the work would be to develop high-efficiency paintable solar cells and water purification methods and devices that use sunlight.

“This mechanism can be extremely significant for light harvesting,” she said. “What’s more important is we’ve come up with an easy way to achieve that, to make a UV-absorbing material to become a visible light absorber by narrowing the bandgap.”

The key to the discovery is to improve titania’s absorption of visible light or develop visible-light sensitive materials in general, according to researchers. Visible light comprises 43 percent of solar energy, while UV light is only 5 percent. If solar-energy-harvesting materials and panels could harvest more visible light, they could provide more energy and work more efficiently, which is why researchers are trying to tackle this problem through materials science, physics, and other scientific methods.

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Specifically what Li and her team discovered is that when titania particles are mixed with graphene quantum dots, the resulting composite absorbs visible light using a quantum-confined bandgap narrowing mechanism, she said.

“More significantly, the bandgap can be tuned by the size of graphene quantum dots,” Li added. “Flexible tuning of bandgap is extremely desirable in semiconductor-based devices.”

Li and her colleagues published a paper about their work in the journal Chemical Communications.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 15 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.