Scientists have uncovered a cheap and sustainable way to build solar cells that convert light to energy using bacteria.
Published in the journal Small, the research comes from the University of British Columbia, who not only managed to generate a current in the cells stronger than any previously recorded from such a device, but ensured it worked as efficiently in dim light as in bright light.
The researchers said the innovation could be a step toward wider adoption of solar power in places like parts of northern Europe where overcast skies are common. With further development, these solar cells - called "biogenic" because they are made of living organisms - could become as efficient as the synthetic cells used in conventional solar panels.
"Our solution to a uniquely British Columbia problem is a significant step toward making solar energy more economical," said professor in UBC's department of chemical and biological engineering, Vikramaditya Yadav, who led the project.
Solar cells are the building blocks of solar panels and do the work of converting light into electrical current. Previous efforts to build biogenic solar cells have focused on extracting the natural dye that bacteria use for photosynthesis. However, it's a costly and complex process that involves toxic solvents and can cause the dye to degrade.
The researchers' solution was to leave the dye in the bacteria and genetically engineer E. coli to produce large amounts of lycopene, a dye that is effective at harvesting light for conversion to energy. The researchers coated the bacteria with a mineral that could act as a semiconductor, and applied the mixture to a glass surface.
With the coated glass acting as an anode at one end of their cell, they generated a current density of 0.686 milliamps per square centimetre, an improvement on the 0.362 achieved by others in the field, they said.
"We recorded the highest current density for a biogenic solar cell," explained Yadav. "These hybrid materials that we are developing can be manufactured economically and sustainably, and, with sufficient optimization, could perform at comparable efficiencies as conventional solar cells."
In an ideal world, however, the process wouldn't kill the bacteria, so they can produce the dye indefinitely. Nevertheless, the researchers believe the process reduces the cost of dye production to about one-tenth of what it would be otherwise.
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