Solar Cells Info

Nanotechnology meets solar energy
By Ed Taylor, Tribune
December 10, 2006
Source: East Valley Tribune of Arizona
http://www.eastvalleytribune.com/index.php?sty=80408

Two of the hot-button fields of scientific study — nanotechnology and solar energy — are being combined by a team of Arizona State University researchers in an effort to find a cheap source of household energy for the nation’s future. The team headed by Stuart Lindsey, director of the Center for Single Molecule Biophysics at the Arizona Biodesign Institute; Rudy Diaz, associate professor of electrical engineering; and chemistry professor Devens Gust, have received a $1.1 million grant from the National Science Foundation to explore creation of infinitesimal nanoscale devices on the molecular level that can convert sunlight into electric current.

The idea is to try to overcome the major problem of photovoltaic solar energy — its relative inefficiency, which makes the cost of electricity produced by solar cells four times greater than electricity produced by nuclear or fossil fuels. ,“If it works, there is a potential to bring the fabrication cost down to a very small amount,” Lindsey said.

That’s a big “if,” Lindsey admits. He said the idea of using nano-structures to convert sunlight into electricity is still theoretical. But the fact that the NSF is willing to fund research indicates an increasing interest in the concept by the scientific community, he said. One nanometer is one billionth of a meter — about 10 times the size of a single atom. By way of comparison, 10 nano- meters is 1,000 times smaller than the diameter of a human hair.

Nanotechnology is an emerging scientific field involving the control of individual atoms and molecules to create tiny machines and structures. Using a process that is similar to what occurs in nature in the process of photosynthesis, it is possible to push electrons from one molecule to another to create an electric current, Lindsey said.

The ASU group is proposing to build arrays of antenna structures made of metal particles at the nanoscale level, which would concentrate light and make that process of converting it to electricity more efficient and less expensive than can be achieved by traditional silicon solar cells. The tiny structures will be able to self-assemble if they are “painted” with strands of DNA that array themselves according to their natural chemical properties.

“The idea of using DNA as a manufacturing tool may seem crazy, but actually DNA is a wonderful tool for building tiny nanostructures,” Lindsey said. The idea of applying that principal to electricity production was devised by Hao Yan, an ASU post-graduate student participating in the research project.

A layer of nanostructures could theoretically be placed onto a thin film that could be rolled onto the roof of a house to generate electricity, he said. Lindsey expects the ASU team will know if the concept is feasible within a couple of years. When a practical roll of nanostructure photovoltaic material might be ready for a homeowner’s roof is unknown. The team hasn’t yet been able to create an electric current using nanomaterials, but researchers have built interesting structures at that level including one array that spells out the letters “ASU.”