The finding, reported in the journal Nature Materials, offers a new way to process conventional silicon by slicing the brittle wafers into ultra-thin layers and carefully transfers them onto a flexible surface.
“We can make it thin enough that we can put it on plastic to make a rollable system. You can make it gray in the form of a film that could be added to architectural glass. It opens up spaces on the fronts of buildings as opportunities for solar energy.” said John Rogers of the University of Illinois at Urbana-Champaign, who led the research.
Many international companies are making thin-film solar cells, but they are usually less efficient at converting solar energy into electricity than conventional cells.
Rogers’ team uses a special etching method to slice very thin solar chips off the surface of single crystal silicon wafers which are highly efficient but, in their current form, rigid and fragile. The sliced chips are 10 to 100 times thinner than a normal silicon wafer, and the size can be adapted to the application. Once sliced, the bits of silicon chips are picked up by a special device and deposited on the target surface “like a rubber stamp”.
“These silicon solar cells become like a solid ink pad for that rubber stamp. The surface of the wafers after we’ve done this slicing become almost like an inking pad,” said Rogers. “We just print them down onto a target surface.” “The final step is to electrically connect these cells to get power out of them,” he said.
Adding flexibility to the material would make the cells far easier to transport. Rogers envisions the material being “rolled up like a carpet and thrown on the truck.”
The technology has been licensed to a startup company called Semprius in Durham, North Carolina.