Bacteria-powered solar cell converts light to energy, even under overcast skies

University of British Columbia researchers have found a cheap, sustainable way to build a solar cell using bacteria that convert light to energy. Their cell generated a current stronger than any previously recorded from such a device, and worked as efficiently in dim light as in bright light. 

This innovation could be a step toward wider adoption of solar power in places like British Columbia and 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.

Solar cells are the building blocks of solar panels. They 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. It's a costly and complex process that involves toxic solvents and can cause the dye to degrade.

The UBC researchers' solution was to leave the dye in the bacteria. They genetically engineered E. coli to produce large amounts of lycopene—a dye that gives tomatoes their red-orange colour and is particularly 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.

"We recorded the highest current density for a biogenic solar cell," said Vikramaditya Yadav, a professor in UBC's department of chemical and biological engineering who led the project. "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."