Solar nanowires promise efficient, low-cost solar power

University researchers claim to have found a way of channeling solar energy directly into electrical appliances without the need for conventional solar panels.

Researchers at the Georgia Institute of Technology say they have efficiently turned light into electricity using fibre-optic cables that have been attached to solar cells.

The system uses fibre optics of the type used by the telecommunications industry and covers them with zinc oxide nanowires to increase their surface area. The nanowires are then coated with dye-sensitised solar cells that convert light to electricity.

The researchers said that sunlight entering the optical fibre passes into the nanowires, where it interacts with the dye molecules in the cells to produce an electrical current.

They added that the cells are inexpensive to manufacture, flexible and mechanically robust. While they are currently less efficient than the silicon-based cells used in traditional solar panels, this can be countered by using the nanostructure arrays to increase the available surface area, making them in practice six times more efficient than conventional solar panels.

"You have multiple light reflections within the fibre, and multiple reflections within the nanostructures," explained Zhong Lin Wang, professor at the Georgia Tech School of Materials Science and Engineering, who led the research. "These interactions increase the likelihood that the light will interact with the dye molecules, and that increases the efficiency."

Wang and his research team hope to double the efficiency of the system again by further improving the surface area.

The amount of light entering the optical fibre could also be increased by using lenses to focus the incoming light.

Wang added that the breakthrough had the potential to revolutionise the way solar energy is harvested. "Using this technology, we can make photovoltaic generators that are foldable, concealed and mobile," he said. "Optical fibre could conduct sunlight into a building's walls where the nanostructures would convert it to electricity. This is truly a three-dimensional solar cell."

He admitted that the new solar cells are unlikely to replace silicon-based panels within the next few years, but argued that they will broaden the potential applications for photovoltaic energy.

"This is a different way to gather power from the sun," he said. "To meet our energy needs, we need all the approaches we can get."

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