MIT's developed a technique to print out solar cells on paper, almost as cheaply and easily as printing a document.
The new process uses vapors, rather than the usual liquids, and works at less than 120 degrees C. This means thatordinary untreated paper, cloth or plastic can be used as the substrate.
In order to create an array of photovoltaic cells on the paper, five layers of material need to be deposited onto the same sheet of paper in successive passes, using a mask (also made of paper) to form the patterns of cells on the surface. The process has to take place in a vacuum chamber.
The resulting solar cells 'still function even when folded up into a paper airplane', says MIT. Indeed, MIT claims that a cell printed on PET plastic could be folded and unfolded 1,000 times, with no significant loss of performance.
"We have demonstrated quite thoroughly the robustness of this technology," says professor of electrical engineering Vladimir Bulović.
"We think we can fabricate scalable solar cells that can reach record-high watts-per-kilogram performance. For solar cells with such properties, a number of technological applications open up."
Unsurprisingly, the process could be cheaper than using standard substrates - which often cost twice as much as the active films of the cells themselves. Paper costs a thousandth as much as glass.
The researchers are now trying to improve the devices. Right now, the paper-printed solar cells have an efficiency of about one percent - enough to power a small electronic device. But the team believes this can be increased significantly with further fine-tuning of the materials.