A research discovery by Erik Hobbie, director of the NDSU Materials and Nanotechnology Program, may one day improve solar cells. Hobbie and a team of researchers at the National Institute of Standards and Technology and NDSU took a closer look at a promising nanotube coating. Scientists discovered coatings made of single-walled carbon nanotubes have problems that must be addressed before their full potential is realized.
“The irony of these nanotube coatings is that they can change when they bend,” says Hobbie. “Under modest strains, these films can develop irreversible changes in nanotube arrangement that reduce their conductivity. Our work is the first to suggest this, and it opens up new approaches to engineering the films in ways that minimize these effects.”
The solar power industry has long sought a cheap, flexible, transparent coating that can conduct electricity. If a single material can provide such properties, solar cells might become more cost-effective and potentially be used in materials such as clothing. According to Hobbie, transparent conductive coatings can be made of indium-tin oxide, but they are rigid and expensive.
Hobbie and other scientists view carbon nanotubes as one possible solution. Nanotubes can be formed into transparent conductive coatings that are strong yet deformable like paper or fabric. Research conducted by Hobbie and his team, however, found that something akin to microscopic wrinkles can disrupt the random arrangement of nanotubes, and alter the coating’s ability to conduct electricity.
The research team is investigating ways to address the problem. According to Hobbie, films could be made thin enough to avoid wrinkling or a second interpenetrating polymer network might solve the problem. “These approaches might allow us to make coatings of nanotubes that could withstand large strains while retaining the traits we want,” says Hobbie.
Results from the study are published in the article, “Wrinkling and Strain Softening in Single-Wall Carbon Nanotube Membranes,” which appeared in Physical Review Letters.
Hobbie is a physics professor in the Department of Physics and the Department of Coatings and Polymeric Materials at NDSU. He also is director of NDSU’s Materials and Nanotechnology Graduate Program offering students a unique opportunity to participate in interdisciplinary research. It is the only program of its kind in North Dakota. NDSU faculty from chemistry, civil engineering, coatings and polymeric materials, mechanical engineering, physics, engineering and architecture contribute to the Materials and Nanotechnology Program. Researchers in the program also collaborate with NDSU’s Center for Nanoscale Science and Engineering. Hobbie previously was a senior scientist at the National Institute of Standards and Technology. He earned a doctorate in physics from the University of Minnesota.
