Nano-flowers, newly created structures composed of germanium sulfide (GeS), have the potential to open the door to next-generation solar cells and energy storage devices. These ‘flowers’, created by researchers from North Carolina State University out of a semiconducting material, feature an enormous surface area, thanks to being covered in many extremely thin petals.
“Creating these GeS nanoflowers is exciting because it gives us a huge surface area in a small amount of space,” says Dr. Linyou Cao, an assistant professor of materials science and engineering at NC State and co-author of a paper on the research. “This could significantly increase the capacity of lithium-ion batteries, for instance, since the thinner structure with larger surface area can hold more lithium ions. By the same token, this GeS flower structure could lead to increased capacity for supercapacitors, which are also used for energy storage.”
The flower-shaped structures were created by researchers through a process that begins with heating GeS powder in a furnace so that it vaporizes. After that, the vapor gets blown into a cooler area of the furnace, “where the GeS settles out of the air into a layered sheet that is only 20 to 30 nanometers thick, and up to 100 micrometers long. As additional layers are added, the sheets branch out from one another, creating a floral pattern similar to a marigold or carnation.”
“To get this structure, it is very important to control the flow of the GeS vapor,” Cao says, “so that it has time to spread out in layers, rather than aggregating into clumps.”
GeS behaves similarly to graphite, settling into structurally organized layers and sheets. It’s considerably different than graphite with regards to its atomic structure though, GeS is an excellent material for creating solar cells, very effective at converting solar energy into electricity. GeS also happens to be relatively inexpensive and is non-toxic, another huge plus when it comes to solar cells. Currently, many of the manufacturing processes used by solar cell producers are ‘expensive’ and make use of toxic materials, though there have been continuing improvements in these areas the last few years.
The research paper, called “Role of Boundary Layer Diffusion in Vapor Deposition Growth of Chalcogenide Nanosheets: The Case of GeS,” was just published in the journal ACS Nano.