Microscopic organisms were some of the first things to tap into the Sun for energy, so it follows to use them to make better solar cells. Now, researchers at the University of British Columbia (UBC) have developed a new way to build solar cells containing bacteria, which are more efficient than similar systems and can even work on dim, cloudy days.

Normally, to make "biogenic" solar cells out of living organisms, a dye is extracted from bacteria that allows them to photosynthesize light. Unfortunately, this process can be complex and may require toxic solvents.

So, the UBC team used a deceptively simple alternative: the bacteria themselves. First, they genetically engineered E. coli to overproduce a dye called lycopene, which is naturally effective at performing photosynthesis. Then, the bacteria were coated in a semiconductor material and applied to a glass plate.

Exposing the device to light, the team was able to record a current density of 0.686 milliamps per sq cm, almost twice that normally reached by other biogenic solar cells. The team also said the cell was able to work just as efficiently in dim light, which could expand its usefulness to less sunny parts of the world.

"We recorded the highest current density for a biogenic solar cell," says Vikramaditya Yadav, lead researcher on 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."

The researchers estimate that their process costs just 10 percent of the usual method of dye extraction. For now, the semiconductor process kills the bacteria, but the team hopes to eventually find an alternative technique that keeps them alive, where they could continuously produce the dye and increase the longevity of the solar cell.

The research was published in the journal Small.