Stanford University researchers say they have developed a “peel-and-stick” solar cell that can be attached to a variety of hard surfaces, an innovation they say could vastly expand the potential for solar energy technology. Normally, thin-film solar cells are attached to rigid, often heavy, silicon and glass substrates because most unconventional surfaces aren’t compatible with the thermal and chemical processes involved in producing the cells. The new process gets around that challenge, the scientists say, because it does not require any fabrication to occur on the final substrate surface. Instead, it involves pressing an ultra-thin film of nickel, a silicon/silicon dioxide wafer, and a protective polymer into a “sandwich,” and then attaching a layer of thermal release tape. When dipped in room-temperature water, the thin-film solar cell can be peeled from the original wafer and attached to a wide range of surfaces, from window glass to cellphones.