Rainbow-powered solar cells come closer to reality

Washington, October 17 : Ohio State University researchers have overcome two of the major obstacles to solar power by developing a new material that can absorb all the energy contained in sunlight, and generate electrons in a way that makes them easier to capture.

The researchers have revealed that they created the hybrid material by combining electrically conductive plastic with metals, including molybdenum and titanium.

"There are other such hybrids out there, but the advantage of our material is that we can cover the entire range of the solar spectrum," explained Malcolm Chisholm, Distinguished University Professor and Chair of the Department of Chemistry at Ohio State.

Sunlight contains the entire spectrum of colours-all the colours of the rainbow-that are actually different energy levels, or frequencies of light.

The existing solar cell materials can only capture a small range of frequencies, and thus capture only a small fraction of the energy contained in sunlight.

Chisholm insists that the new material can absorb all the energy contained in visible light at once.

The researcher has revealed that the material generates electricity just like other solar cell materials do: light energizes the atoms of the material, and some of the electrons in those atoms are knocked loose.

Generally, the electrons flow out of the device as electrical current, and that is where most solar cells run into trouble.

The electrons only stay loose for a tiny fraction of a second before sinking back into the atoms from which they came, and they must be captured during the short time they are free. The task, called charge separation, has been a major trouble for scientists to date.

Chisholm, however, says that in the new hybrid material, electrons remain free much longer than ever before.

"This long-lived excited state should allow us to better manipulate charge separation," the researcher said.

It may take several years before the new material finds use in commercial applications, but Chisholm stresses that its creation goes to show that hybrid solar cells with unusual properties can be developed.

A research article describing the new material has been published in the Proceedings of the National Academy of Sciences (PNAS).

ANI