Scientists at the Massachusetts Institute of Technology, also known as MIT, announced Thursday that they have found a way to get more power from sunlight. Better solar panels could be on their way.
The engineers discovered that they could increase the amount of power that each solar cell carries by coating the metal surface of the cell with "high-index dielectrics," a fancy name for a certain type of oxygen-based material.
The magic happens when light hits the oxide material. The combination of UV photons and the coating knocks loose extra electrons, which are needed to power the cell. The electrons it releases are "surface plasmons," which are spinning electron clouds.
"Our study reveals a surprising fact: Absorption of visible light is directly controlled by how deeply the electrons spill over the interface between the metal and the dielectric," says Nicholas Fang, who co-authored the study. "In earlier studies," Fang says, "this was something that was overlooked."
This development was completely unexpected, but a delightful surprise. Researchers had actually noticed an increase in electron production when using similar materials, but had thought it was because of defects in the materials. But Fang says they knew that explanation wouldn't hold water for long: there was clearly something going on at the quantum level.
To test their theory, the researchers used a sheet of silver, coated with an oxide. When light hits this combination, it produces a charge. Sure enough, it produced the kind of increased electrons, and thus increased power, they were looking for. They could then alter the oxide layer, making it thicker or thinner, to control the amount and type of light absorbed and converted into energy. And since these types of solar cells are very thin, they would use less material (and presumably be lighter) than the current standard for solar panels.
The new system of using a layer of dielectric materials would also potentially produce much faster solar power (no more office workers stumbling around in the dark while the overhead lights come on), and potentially even be used for high-speed technology like data transmission.
The oxide material is no newfound secret: it has been around for a long time, as a material used for transistors, but had never been used for this application.
The study is published in the journal Physical Review Letters.
Photo: Justin Elliott | Flickr
