Spinach Chemical Fuels Green Solar Cell

July 13, 2004 -- It gave Popeye the power to knock out arch rival Brutus and take the hand of fair Olive Oyl. But someday, spinach could lead to another, more useful form of energy — the electrical kind.

Researchers at the Massachusetts Institute of Technology and the University of Tennessee in Knoxville are working on developing a new type of photovoltaic cell that turns sunlight into electricity using a protein found naturally in the leafy green vegetable.

Marc Baldo, an assistant professor of electrical engineering and one of the project's scientists at MIT, says the research's goal was to come up with a better, more flexible solar cell.

"There are a bunch of ways to make conventional solar cells, most of them are made of silicon and fabricated the same way as silicon chips," says Baldo. "It's a high-energy and high-temperature process that's not really compatible with lightweight [and bendable] plastics."

So, scientists at MIT and the University of Tennessee figured the best way around those limitations was to borrow from Mother Nature.

"We got interested in how plants convert solar energy to help them grow," says Baldo. And while studying the process of photosynthesis, the researchers discovered an interesting fact: the proteins that naturally convert sunlight to plant energy for growth actually produce a tiny, but measurable, amount of electricity.

Baldo and the researchers then isolated these microscopic protein structures, measuring about five or six nanometers in size, from the plant and sandwiched them between a thin gold film attached to a sheet of electrically-conductive, transparent material on one side and an organic layer of conductive material on the other.

When scientists directed sunlight on to the sandwich, the proteins generated electrons which passed from one layer of the sandwich to the other and produced a tiny electrical current.

The team's research work has been published in a recent issue of Nano Letters, a scientific journal.