Advanced imaging technology reveals a bumpy surface of tiny, faceted grains on perovskite solar cells. A big step in helping perovskites reach their potential as the basis for far cheaper and more efficient types of solar cells came this week from a team at Lawrence Berkeley National Laboratory . The scientists found that the surfaces of materials with this distinctive crystal structure vary dramatically in performance. Perovskites are made up of tiny grains that are faceted, not unlike diamonds, says Alexander Weber-Bargioni, one of the lead researchers, and some facets turn out to be much more efficient at producing electrical current than adjacent ones. The result suggests that optimizing the favorable facets would allow far more efficient solar cells. Some of the facets studied by the Berkeley group can convert the energy in sunlight into electricity at a rate of close to 31 percent, which is the theoretical efficiency […]