How Quantum Physics Could Power the Future

The strange behavior of quantum physics might seem too unpredictable to rely on for our energy needs, but new technologies hope to capitalize on its very strangeness.

The most familiar of these quantum tricks is the fact that light acts both like a wave and a particle.

This dual nature is utilized in solar power technology. Incoming sunlight is concentrated by mirrors and lenses that rely on the wave-like properties of light.

Once inside a solar cell, however, this focused light collides with electrons in a particle-like way, thus freeing the electrons to create an electric current.

The next generation of solar cells may employ tiny bits of semiconductor material called quantum dots. These nanometer-sized devices are so small that only a handful (anywhere from 1 to 1,000) of free electrons can reside inside.

Because of these cramped quarters, a quantum dot behaves like an artificial atom in that its electrons can reside only at specific (so-called quantized) energy levels. These levels define exactly what wavelengths of light the dot will absorb.

"Quantum dots have a host of unusual properties compared to bulk semiconductors," said Arthur Nozik of the National Renewable Energy Laboratory, part of the U.S. Department of Energy.

He and his colleagues are looking at how a single light particle (or photon) can enter a dot and excite several electrons, rather than the usual one.

Other researchers are looking to tune the wavelengths at which a dot absorbs light by making it bigger or smaller.

Solar cell manufacturers may one day be able to mix together dots of different sizes to absorb sunlight along a wide range of wavelengths.

Source: http://www.foxnews.com/story/0,2933,396282,00.html