ASU professor studies ‘dark art’ of solar

A professor at Arizona State University is taking solar science back to the basics.

“The basic fundamental principles of how solar cells work is understood,” said ASU professor Mark van Schilfgaarde. “But the devil is in the details.”

Schilfgaarde does basic research at the earliest, most elementary level. And that’s not to say his science is simple. It’s anything but. He aims to understand the elements that go into solar cells and why they work so that the solar industry might one day be able to benefit from his research and develop a better, more efficient solar cell.

He works on a molecular level, watching electrons split and trying to find out what brings them back together and how to keep them apart longer so they will generate more energy, he said.

“What’s actually happening in a solar cell is more or less unknown. It’s a black art,” van Schilfgaarde said. “I guess you could say they’re operating the dark.”

He said solar cell manufacturers have a recipe, and they know it works, but they don’t know, at a molecular level, why it works. That recipe, which consists mostly of silicon in most solar products, is actually highly inefficient, van Schilfgaarde said.

The average commercial solar cell today achieves just 15 to 20 percent efficiency. Not only that, but some of the key ingredients in today’s solar cells are not especially abundant.

Schilfgaarde noted that indium is one of those rare Earth minerals that there may not be enough of, especially as its mined at record paces now to supply technology companies that use it for their flat-panel TVs and touch-screen phones and computers.

“The material supply issue was ignored because scientists just wanted to get solar on the map,” van Schilfgaarde said.

The strides in solar development and implementation today are astounding, and van Schilfgaarde said he’s ecstatic to see the industry taking off today the way he hoped it would in the 1970s when president Jimmy Carter installed solar thermal panels on the White House.

But now, it’s time to take a step back and see if there is a better, more sustainable way to build solar cells, he said.

“Along that path, I tired to design a cell that only used Earth-abundant material,” he said.
Van Schilfgaarde specializes in calculating the properties of materials. He believed that Calcopyrite, a copper iron sulfide mineral, combined with zinc, Germanium and Arsenic would be the perfect combination of Earth-abundant materials to create a more efficient solar cell.

“Theory says it should work,” he said.

But alas, the experiment didn’t pan out.

Schilfgaarde continues to study the basic science behind what makes solar cells work and how they might work better.