California Institute of Technology physics professor Harry Atwater has come up with a new way of making efficient solar cells that use only 1 to 2% of the silicon needed to make conventional silicon based photovoltaic solar cells.
“Our technology uses 50-100 times less silicon,” Atwater said, “in the form of a sparse array of wires. And that sparse array of wires has exactly the same light absorption and electricity-collection properties as the conventional silicon wafer cell.”
The cost of the purified silicon needed for silicon based solar cells is very high, so anything that cuts down on the amount of silicon used leads to cheaper solar cells. Unfortunately, most designs that cut the amount of silicon, or use lower grades of silicon, also reduce the efficiency of the cells. But Professor Atwater says that with his nanowire design the efficiency stays high and that the absorption rate is even higher with his methods. “The light comes in and is both directly absorbed by the wires, and some of the light bounces around in between the wires. And that bouncing around or multiple scattering in between the wires results in dramatically enhanced absorption. In fact, the absorption enhancement that we see is in the range of 20 to 50 times the single-pass absorbance.”
Another benefit is that he’s creating his cells on a thin plastic substrate, which makes for light and flexible solar cells. Professor Atwater says that these cells could be easily incorporated directly into roofing material, or anywhere you don’t have a flat surface, such as the roof of a car. He thinks that this new cell design could be commercialized easily since it uses current manufacturing techniques and won’t require any new technology to mass produce.