A flexible solar-cell design is reported online this week in Nature Materials that uses only one percent of the material used in conventional devices. Unlike many other flexible solar-cell designs, this new design achieves a high light-conversion efficiency. The possible applications for such lightweight, yet efficient solar cells could range from car sunroofs to devices that can be placed on clothing.

To achieve such high levels of light absorption while employing significantly less of the costly semiconductor material, Harry Atwater and colleagues use small micrometre-sized rods of silicon in their device. Incoming light bounces back and forth multiple times between the rods in the devise until it is absorbed. In order to ensure that the light is guided more efficiently, the researchers use small alumina nanoparticle reflectors placed between the rods. The overall result is that up to 85% of usable incident sunlight is absorbed.