|These flexible solar cells bring us closer to kicking the fossil-fuel habit |
No solar material has managed to supplant silicon. Perovskites, which are far cheaper and can be made into flexible modules, could change that. Last December, researchers in a lab in Oxford, England, shined a sun lamp onto a tiny solar cell, only about one-centimeter square.
The device was actually two cells, stacked one atop the other. The bottom one was made of the type of silicon used in standard solar panels. But the top was perovskite, a material with a crystal structure that’s particularly adept at turning light into electricity.
A pair of probes attached to the so-called tandem solar cell measured its performance. Other researchers in the lab at Oxford PV, a company spun out of the university last year, gathered behind a flat-screen monitor, waiting expectantly for a calculation of the cell’s efficiency to appear. When it did, they exchanged high fives. The cell had converted 28% of the energy in the light into electricity, a new efficiency record for a perovskite-on-silicon device. An independent test confirmed it a few days later, after the tiny cell was put on a plane to the National Renewable Energy Laboratory (NREL) in Golden, Colorado.
While silicon panels might dominate the market—with around 95% market share—silicon is not an especially good solar material. It mainly uses light from the red and infrared end of the solar spectrum, and it has to be fairly thick and bulky to absorb and convert photons. The most efficient silicon solar panels on the market achieve less than 23% efficiency, while the theoretical maximum for a single layer of silicon is around 29%.
Read More $ MIT Technology Review