'Green' solar cell is made from plants

To make super cheap solar cells, MIT researchers look to commandeer the process of photosynthesis in plants.

In a mashup of biology and electronics, researchers said they've made progress in making low-cost solar cell from plants.

A paper published in Scientific Reports today describes an improved method for making electricity-producing "biophotovoltaics" without the sophisticated laboratory equipment previously needed. Researchers said custom-designed chemicals could be mixed with green plants, even grass clippings, to create a photovoltaic material by harnessing photosynthesis.

"Take that bag (of chemicals), mix it with anything green and paint it on the roof," said MIT researcher Andreas Mershin, who is one of the paper's co-authors, in a statement. He imagines that this sort of cheap solar cell could be used by people in developing countries who don't have the power grid to charge lamps or cell phones.

The advance represents a 10,000 percent efficiency improvement on previous plant-based solar cells, but these cells are far from being practical. Experimental solar cells made using this process only convert 0.1 percent of sunlight to electricity, which would need to improve tenfold to be practical, Mershin said.

Scientists for years have sought to make solar cells from the set of molecules within plant cells that do the work of photosynthesis, called photosystem-I. However, this material required specialized thin-film deposition and optical equipment. And the current produced was too low.

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Mershin was able to create a workable solar cell made using a combination of new materials that isolate the PS-I molecules and form an array of tiny zinc oxide nanowires, which carry the flow of current and provide a large surface area. These nanowires, which also provide structure for a multi-layered solar cell, can be grown at room temperature on a variety of flexible and inexpensive substrates, according to the paper.

"After many ears of research, we've managed to make the process of extracting this protein and stabilizing it and putting on a surface that is made in a way to allow for the photovoltaic effect to happen to be very easy," he said in a video provided by MIT.

In their paper, the researchers note a number of challenges to these "green" solar cells, including the durability and efficiency. But the initial performance tests for this new technique offers a promising route for further research, they said. "Commandeering this intricately organized photosynthetic nanocircuitry and re-wiring it to produce electricity carries the promise of inexpensive and environmentally friendly solar power," according to the paper.

ORIGINAL: CNet

by Martin LaMonica @mlamonica

February 2, 2012 7:52 AM PST