Published on February 20th, 2013 | by James Ayre0
3-D Solar Cells May Receive Big Boost Thanks To New Semiconductor Nano-Shish-Kebabs
February 20th, 2013 by James Ayre
A new type of nano-sized structure, looking something like a “nano-shish-kebab,” has been developed by researchers at North Carolina State University. The seamless three-dimensional structure, consisting solely of germanium sulfide (GeS) crystals, could be useful in the development of 3-D solar cells, next-generation sensors, supercapacitors, and photodetectors.
Looking like a row of nano-sheets run through by a nano-wire, it is actually one solid, shared, crystalline structure. The researchers say that this is the first engineered nano-material to consist of one-dimensional and two-dimensional structures while having a shared crystalline structure.
“Combining the nanowire and nanosheets into a single ‘heterostructure’ creates a material with both a large surface area and — because GeS is a semiconductor — the ability to transfer electric charges efficiently. The nanosheets provide a very large surface area, and the nanowire acts as a channel that can transmit charges between the nanosheets or from the nanosheets to another surface.”
“We think this approach could also be used to create heterostructures like these using other materials whose molecules form similar crystalline layers, such as molybdenum sulfide (MoS2),” says Dr. Linyou Cao, an assistant professor of materials science and engineering at NC State and co-author of a paper on the research. “And, while germanium sulfide has excellent photonic properties, MoS2 holds more promise for electronic applications.”
According to Cao, the process is especially interesting because “it is inexpensive and could be scaled up for industrial processes.”
The nano-shish-kebabs were created by, first, making a GeS nanowire about 100 nanometers in width; then, exposing it to air, which causes nucleation sites to form on the wire surface via weak oxidation; and then, after that, exposing the wire to GeS vapor, resulting in the formation of “two-dimensional nanosheets at each of the nucleation sites.”