Sep 28, 2010 11:46 GMT  ·  By

Until now, experts have placed a lot of emphasis on producing solar cells that are as smooth as possible, but a recent investigation suggests they may have been on a wild goose chase all along.

Investigators from the Stanford University have shown in a new set of experiments that roughening silicon wafers up a bit results in them becoming increasingly capable of absorbing sunlight.

In other words, if you can get light to ricochet inside thin films, then there's a good chance that the structure will absorb a lot more photons, eliminating electrons, and producing electrical currents.

Stanford engineers believe that their recent discovery is the key towards making solar cell technology cheap and efficient in producing electricity. At this point, costs are prohibitive to many.

An important part of the new discovery is the fact that reducing the thickness of the films that cover up solar cells plays a crucial role in boosting the device's efficiency.

The new devices rely on using a technology that is aptly called “light trapping.” The concept refers to getting a grip on solar cells for long enough to squeeze the maximum amount of light out of it.

“The longer a photon of light is in the solar cell, the better chance the photon can get absorbed,” explains Stanford associate professor of electrical engineering, Shanhui Fan.

The expert is the senior author of a new investigation detailing the findings, which appears in the latest online issue of the esteemed journal Proceedings of the National Academy of Sciences (PNAS).

He goes on to explain that the number of photons a material can absorb dictates its overall efficiency in conducting light conversion. This is the most important measure to quantify a solar panel's performances by.

“We all used to think of light as going in a straight line. For example, a ray of light hits a mirror, it bounces and you see another light ray,” Fan says.

“That is the typical way we think about light in the macroscopic world. But if you go down to the nanoscales that we are interested in, hundreds of millionths of a millimeter in scale, it turns out the wave characteristic really becomes important,” the expert goes on to say.

The group discovered that light can indeed be trapped inside a material for longer periods of time when the scale of measurement is lowered beyond the wavelength of the light being absorbed.

“The amount of benefit of nanoscale confinement we have shown here really is surprising. Overcoming the conventional limit opens a new door to designing highly efficient solar cells,” says PhD student Zongfu Yu.