Scientists have figured out a standardized way to make nanowires out of perovskite, a material that could one day make solar energy cheap and ubiquitous. Just a few years ago, cells made from the relatively inexpensive substances had a solar efficiency rating of just 3.8 percent. Fast-forward to 2015, and they can now convert 21 percent of light hitting them to electricity, drawing the attention of scientists and solar panel manufacturers alike. Using nanowires instead of nanoparticles further increases efficiency, because the wires act as "direct conductive highways" to transmit current more efficiently. So far, though, an easy way to build them has eluded researchers.