Discovery could lead to 'optical battery'

ANN ARBOR, Mich., April 19 (UPI) -- U.S. researchers say an unexpected magnetic effect of light could lead to solar power without traditional semiconductor-based solar cells.

The finding could lead to a way to make an "optical battery," University of Michigan researcher Stephen Rand said. The findings fly in the face of long-held tenets in physics about the properties of light, a university release said Tuesday.

Light has electric and magnetic components, but until now scientists considered the effects of its magnetic field were so weak that they could be ignored.

Rand and his colleagues discovered that at the right intensity, when light is traveling through a material that does not conduct electricity, it can generate magnetic effects 100 million times stronger than previously expected.

"You could stare at the equations of motion all day and you will not see this possibility," Rand said. "We've all been taught that this doesn't happen. It's a very odd interaction. That's why it's been overlooked for more than 100 years.

"This could lead to a new kind of solar cell without semiconductors and without absorption to produce charge separation," Rand said. "In solar cells, the light goes into a material, gets absorbed and creates heat. Here, we expect to have a very low heat load.

"Instead of the light being absorbed, energy is stored in the magnetic moment. Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power source."

This new technique could make solar power cheaper, the researchers say, predicting they can achieve 10 percent efficiency in converting solar power to usable energy.

That's equivalent to today's commercial-grade solar cells, they said.