To make the ultrathin crystalline films used in everything from solar cells to solid state lasers, materials scientists must use complex, expensive machines to lay them down one atomic layer at a time. These techniques craft films into a single crystal without the breaks or defects that would disrupt their electronic and optical properties. But more often, manufacturers use a cheap technique to spin liquids into smooth films, which harden after they are applied to a surface. These coated films rarely form a single crystal, making them serviceable, but inferior.
Now, researchers report today in Science that they can “supersaturate” these liquids with precursor compounds, so that as they spin, they form multiple crystals that fuse together into one, unbroken crystal (seen above in an alloy of cesium, lead, and bromine). The new approach, they suggest, could improve light harvesting in solar cell materials called perovskites and ramp up the speed and performance of flexible electronic devices integrated into everything from curved car dashboards to fabrics.