When it comes to producing earth-friendly solar energy, pink may be the new green, according to Ohio State University researchers.

University scientists have developed new dye-sensitized solar cells (DSSCs) that get their pink color from a mixture of red dye and white metal oxide powder in materials that capture light. Currently, the best of these new pink materials convert light to electricity with only half the efficiency of commercially available silicon-based solar cells, but they do so at only one-quarter of the cost, said Yiying Wu, assistant professor of chemistry at Ohio State.

“We believe that, one day, DSSC efficiency can reach levels comparable to any solar cell,” he said. “The major advantage of DSSCs is that the cost is low. That is why DSSCs are so interesting to us and so important.”

In a recent issue of the Journal of the American Chemical Society, Wu and his team reported that they have made a new DSSC material, using zinc stannate, which is the first time researchers have made a DSSC from anything other than a simple oxide. Wu and his colleagues chose zinc stannate because it belongs to a class of more complex oxides with tunable properties.

“This opens up new possibilities for how scientists may tailor the properties of DSSCs in the future,” he said.

Why pink?

Traditional solar cells look blue because of an antireflective coating that boosts absorption of green light, which is the strongest in the solar spectrum. Wu’s materials don’t have that antireflective coating.

Color determines the wavelength of light a solar cell can capture, so adjusting the color lets scientists optimize particular properties in how the device will function. So far in the development of DSSCs, scientists have gotten the best performance from red ruthenium dye, which actually appears pink, so it is possible when installing solar power systems in the future, you could see pink instead of blue.

Last year, Wu and his team achieved 8.6 percent efficiency, which is roughly half of the 15 percent efficiency typical of commercially available silicon solar cells. Currently, they are experimenting with ways to increase that efficiency.   EC