Solar power research is a big deal. Scientists have been searching for a way to improve photovoltaic efficacy for years by developing new technologies – from giant solar concentrator arrays to satellites that beam power back to Earth. Now, Stanford University researchers have developed what they call the thinnest, most efficient photovoltaic wafers ever. Instead of increasing the size of the solar arrays, the researchers created solar wafers with a nano-sized structure that is 1,000 times thinner than any other commercially available thin-film solar cell absorbers.

An electron micrograph shows the cross-sectional view of the record-thin absorber layer created at Stanford. Shown here are three gold nanodots, each about 14-by-17 nanometers in size, coated with tin sulfide.

According to the researchers, the thin film solar wafers are only 1.6 nanometers thin, which cuts down on materials required to produce the cells while making them lighter. At the same time, all of this was done without comprising the solar cells’ ability to absorb visible light. These smaller photovoltaic cells can actually absorb parts of the visible light spectrum with incredible efficiency.

“The coated wafers absorbed 99 percent of the reddish-orange light,” Carl Hagglund, postdoctoral scholar at Department of Chemical Engineering and lead author on the study, said in a statement. “We also achieved 93 percent [light] absorption in the gold nanodots themselves.”

The Stanford scientists achieved these record setting results by embedded their solar power wafers with trillions of round gold nano-sized particles. Each gold nanodot wafer is less than the size of a fingerprint and contains about 520 billion nanodots per square inch. The nanodots themselves measure about 14 nanometers tall and 17 nanometers wide.

The next step for the Stanford team is to demonstrate that the technology can be used in actual solar cells. To this end, the researchers are looking into building structures using ultrathin semiconductor materials that can absorb sunlight. The final and ultimate goal, however, is to develop better solar cells that can absorb the most amount of light with the smallest amount of material possible.

+ Stanford University

Image © Mark Shwartz