Scientists at the US Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) developed a new perovskite ink with a long processing window that allows the scalable production of perovskite thin films for high-efficiency solar cells.   Proven highly efficient at converting sunlight into electricity, perovskite solar cells have yet to move beyond the laboratory. The crystalline structure of perovskites must be carefully grown upon a substrate, which is normally done by laboratory...