What is the best shape for nanomaterials that move energy in solar cells? When it comes to the semiconductor germanium sulfide, the answer appears to look a lot like a peony. According to new research published in the American Chemical Society's ACS Nano, such "nanoflowers" have the potential to improve solar cells and other technologies.
The key is the surface area of all those petals, which suddenly makes much more of the semiconducting material available to interact with incoming light. To make the flower shape, materials scientist Linyou Cao of North Carolina State University in Raleigh and his colleagues first vaporized a germanium sulfide powder, then blew the resulting vapor to a cooler chamber where it deposited as a thin sheet, less than 30 nanometers wide.
Laying sheet upon sheet in this way allowed the researchers to build this crystalline nano-flower, much as an origami artist might use paper to achieve a similar configuration. Cao likens the result to a marigold or carnation, which suggests that when it comes to a germanium sulfide solar cell, the guide to the proper shape for harvesting sunlight may not be a plant's leaves, but rather its flowers.