Along the many trails to better solar cells, some paths may be better than others. (If they don’t turn out to be dead-ends.) Here’s an approach to solar (photovoltaic) cells from a research team at the California Institute of Technology (USA). It uses long silicon wires (microscale threads) embedded in a polymer sheet, and has impressive features:
It’s flexible: Because it uses wires of silicon on a polymer (plastic) base, this solar cell can flex (most traditional solar cells cannot). The flexibility may have a myriad of applications.
It’s more efficient: Researchers found that the silicon wires did not have to be closely packed to achieve efficiency. In fact, there was a tendency for the wires to each act like a cell, and that an array of wires tends to create a secondary absorption pattern between the wires. The claim is for up to 85% efficiency in absorbing light energy and over 90% efficiency in converting the energy to electricity. If these figures hold up, this will be a very significant advance in efficiency for solar cells.
It’s less expensive: In most solar cells the silicon is the most expensive component. In this design, only between 2 and 10% of the surface is silicon, which represents a major cost savings over traditional silicon solar cells.
The principal caveat is that this is still a laboratory approach. There is much testing yet to be done, particularly in scaling the solar cells from a present size of a few centimeters up to the commercial cell sizes at hundreds of square centimeters.