Peel-and-stick solar cells
EDN Staff - January 15, 2013
Researchers at Stanford University claim to have developed the world's first peel-and-stick thin-film solar cells (TFSCs) that don't require any modification of existing processes or materials. The new process would allow the creation of decal-like solar panels that could be applied to virtually any surface.
Unlike with standard thin-film solar cells, the new process doesn't require direct fabrication on a final carrier substrate. Instead, a 300-nm film of nickel (Ni) is deposited on a silicon/silicon dioxide (Si/SiO2) wafer, on which thin-film solar cells are then deposited using standard fabrication techniques, and covered with a layer of protective polymer. A thermal release tape is then attached to the top of the thin-film solar cells as a temporary transfer holder.
Peeling the cells from the wafer involves soaking the structure in a water bath, during which the thermal release tape is slightly peeled back allowing water penetration into the Ni and SiO2 interface, which results in its separation and the peeling off of the thin-film solar cells from the Si/SiO2 wafer. When the solar cells are ready to be applied to a surface, the thermal release tape holding them is heated at 90°C for a few seconds to weaken its adhesion, allowing the cells to be removed. The cells can then be applied to various surfaces - including plastics, paper, glass, metal foils, and textiles - using common adhesives.
Figure: Procedures of the peel-and-stick process. (a) As-fabricated TFSCs on the original Si/SiO2 wafer. (b) The TFSCs are peeled off from the Si/SiO2 wafer in a water bath at room temperature. (c) The peeled off TFSCs are attached to a target substrate with adhesive agents. (d) The temporary transfer holder is removed, and only the TFSCs are left on the target substrate.
Tests have shown that the peel-and-stick thin-film cells remain completely intact and functional, with no loss of the original cell efficiency. Looking beyond solar cells, the researchers believe the process could also be applied to thin-film electronics, including printed circuits, ultra-thin transistors and LCDs. For more, see the original paper, "Peel-and-Stick: Fabricating Thin Film Solar Cell on Universal Substrates."