While the unique shape of Buddhist singing bowls is vital to the creation of their signature sound, a researcher from Australia National University (ANU) has used their design as the inspiration for a new breed of solar cells. In completing his PhD at the University of Cambridge, Dr Niraj Lal found that just as the bowls cause sound to resonate, miniaturized versions can be made to interact with light in much the same way, inspiring solar cells better able to capture sunlight.
Previous research has established that light behaves differently when working at the nanoscale. Downsizing his bowl-inspired cells to this level, Lal, now working at ANU, was able to demonstrate a device with the ability to capture significantly more light and convert it to electricity.
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"Current standard solar panels lose a large amount of light-energy as it hits the surface, making the panels’ generation of electricity inefficient," says Niraj. "But if the cells are singing bowl-shaped, then the light bounces around inside the cell for longer."
Niraj calls this process "plasmonic resonance"" and says his nanobowls perform at four times the efficiency of flat solar cells in the lab, which when made from single materials such as silicon have an efficiency of 25 percent.
Improvements have been made on flat, single structure solar cells by way of tandem devices that stack a number of cells on top of each other. With the cells made from different materials, each with their own light absorption properties, the device is able to catch a wider range of the solar spectrum, enhancing its overall efficiency.
We saw the value of this approach earlier this year, when researchers produced a multi-material, four-junction, four-terminal stacked solar cell that achieved efficiencies of 43.9 percent.
Niraj and his team are now exploring ways that the nanobowl design can be incorporated into these tandem structures. "If we can make a solar cell that ‘sees’ more colors and keeps the right light in the right layers, then we could increase efficiency even further," he says.
The team's research was published in the IEEE Journal of Photonics.