U.S. researchers say they\'ve developed the world\'s first peel-and-stick, flexible thin-film solar cells that can be stuck to virtually any surface. Scientists at Stanford University say the cells overcome a previous limitation inherent in solar cells, that most are rigid and limited in their deployment to stiff and often-heavy fixed panels. Thin-film photovoltaic cells are traditionally fixed on rigid silicon and glass substrates, greatly limiting their uses, said Chi Hwan Lee, a doctoral candidate in mechanical engineering. The peel-and-stick version from Stanford does not require any direct fabrication on the final carrier substrate, he said, greatly expanding the potential applications of solar technology. \"We got around these problems by developing this peel-and-stick process, which gives thin-film solar cells flexibility and attachment potential we\'ve never seen before, and also reduces their general cost and weight,\" Lee said in a Stanford release Thursday. The researchers said they\'ve successfully attached the cells to paper, plastic and window glass among other materials. The flexible cells can be applied to virtually any surface using double-sided tape or other adhesive, they said. \"Now you can put them on helmets, cell phones, convex windows, portable electronic devices, curved roofs, clothing -- virtually anything,\" mechanical engineering Professor Xiaolin Zheng said.