E-Mail IMAGE: Scientists at SLAC National Accelerator Laboratory and Stanford University discovered that squeezing a promising lead halide material in a diamond anvil cell (left) produces a so-called "black perovskite " (right)... view more Credit: Greg Stewart/ SLAC National Accelerator Laboratory Among the materials known as perovskites, one of the most exciting is a material that can convert sunlight to electricity as efficiently as today's commercial silicon solar cells and has the potential for being much cheaper and easier to manufacture. There's just one problem: Of the four possible atomic configurations, or phases, this material can take, three are efficient but unstable at room temperature and in ordinary environments, and they quickly revert to the fourth phase, which is completely useless for solar applications.