Saturday, May 19, 2012

Miles Barr: Printing Solar Cells on Paper and Clothes

Forget about putting solar panels on the roof. Miles Barr wants to make curtains, cell-phone cases, and even shirtsleeves that generate electricity from the sun.

Barr, who earned a chemical engineering Ph.D. at Massachusetts Institute of Technology, is an expert in chemical vapor deposition. That’s a process in which two vapors are piped into a sealed chamber, where they react, creating a thin, solid film around an object inside. The technique isn’t new; it’s been used to add a waterproof layer to fabric, for example. Barr successfully adapted the technology to “print” an electrically active solar cell coating onto ordinary materials, starting with a sheet of paper in 2010. “When we first did that, it really sparked a lot of imagination,” says Barr, 28. “If you can put a solar cell on paper, what else can you put it on?”

Chemical vapor deposition changes the quality of a surface without using extreme temperatures or solvents that might cause damage. When Barr’s team at MIT figured out how to use the process to make solar cells, he says, they went to an office supply store and loaded up on stuff to test it on: “Saran Wrap, copy paper, tissue paper, almost anything you can imagine,” he says. Barr maintains the technique could be adapted for mass production. Because it relies on abundant organic molecules, rather than heavy metals or rare elements, it could be cheap, too. Right now, Barr’s solar cells convert only about 2 percent of the energy in light into electric power, compared with 10 percent to 20 percent for conventional photovoltaic panels, though he thinks he can eventually raise the efficiency to 10 percent.

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