Atomic Movies May Help Explain Why Perovskite Solar Cells Are More Efficient

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https://www6.slac.stanford.edu/news/2017-07-26-atomic-movies-may-help-explain-why-perovskite-solar-cells-are-more-efficient.aspx


Atomic Movies May Help Explain Why Perovskite Solar Cells Are More Efficient
SLAC’s ultrafast 'electron camera' reveals unusual atomic motions that could be crucial for the efficiency of next-generation perovskite solar cells.
July 26, 2017

Menlo Park, Calif. — In recent years, perovskites have taken the solar cell industry by storm. They are cheap, easy to produce and very flexible in their applications. Their efficiency at converting light into electricity has grown faster than that of any other material – from under four percent in 2009 to over 20 percent in 2017 – and some experts believe that perovskites could eventually outperform the most common solar cell material, silicon. But despite their popularity, researchers don’t know why perovskites are so efficient.

Now experiments with a powerful “electron camera” at the Department of Energy’s SLAC National Accelerator Laboratory have discovered that light whirls atoms around in perovskites, potentially explaining the high efficiency of these next-generation solar cell materials and providing clues for making better ones.

“We’ve taken a step toward solving the mystery,” said Aaron Lindenberg from the Stanford Institute for Materials and Energy Sciences (SIMES) and the Stanford PULSE Institute for ultrafast science, which are jointly operated by Stanford University and SLAC. “We recorded movies that show that certain atoms in a perovskite respond to light within trillionths of a second in a very unusual manner. This may facilitate the transport of electric charges through the material and boost its efficiency.”

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Iodine atoms, which surround lead atoms in a perovskite solar cell material studied at SLAC, respond to light in a surprising manner: Within 10 trillionths of a second after a light pulse, iodine atoms rotate around every lead atom as if they are moving on the surface of a sphere with the lead atom at the center. These motions could potentially explain the material’s high efficiency in converting light into electricity. (Greg Stewart/SLAC National Accelerator Laboratory)

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http://advances.sciencemag.org/content/3/7/e1602388