MSGID: 1:317/3 63d9eae3   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Thin, lightweight layer provides radiation barrier for perovskites in   
   space, protection from elements on Earth    
      
     Date:   
         January 31, 2023   
     Source:   
         DOE/National Renewable Energy Laboratory   
     Summary:   
         An ultrathin protective coating proves sufficient to protect   
         a perovskite solar cell from the harmful effects of space and   
         harden it against environmental factors on Earth, according to   
         newly published research.   
      
      
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   FULL STORY   
   ==========================================================================   
   An ultrathin protective coating proves sufficient to protect a perovskite   
   solar cell from the harmful effects of space and harden it against   
   environmental factors on Earth, according to newly published research   
   from the U.S.   
      
   Department of Energy's National Renewable Energy Laboratory (NREL).   
      
      
   ==========================================================================   
   Funded by the U.S. Department of Defense's Operational Energy Capability   
   Improvement Fund (OECIF), the NREL research was done for the Air Force   
   Research Laboratory (AFRL) to develop low-cost innovative energy sources   
   for powering the armed forces worldwide.   
      
   The research is the latest effort to determine the effectiveness of   
   perovskites for use in space applications, where it would be exposed to   
   protons, alpha particles, atomic oxygen, and other stressors. The ability   
   to use perovskites to generate power in space is enticing because they   
   offer a lower-cost and lightweight option to other technologies with the   
   potential for achieving efficiencies similar to those of current space   
   PV technologies.   
      
   Just as on Earth, perovskite solar cells need to have suitable durability.   
      
   However, the environment in space is significantly different. While the   
   biggest challenges on Earth are related to weather, in space perovskites   
   must address the problems that come from radiation bombardment and   
   extreme temperature swings. Perovskites show signs of better tolerance   
   to radiation than many other solar cells, but plenty of testing remains   
   to be conducted.   
      
   Researchers last year ran simulations to demonstrate how exposure   
   to radiation in space would affect perovskites. They determined the   
   next-generation technology would work in space but pointed out the need   
   to encapsulate the cell in some way to provide added protection.   
      
   In the follow-up research, Ahmad Kirmani, lead author of the latest   
   Nature Energy paper, said simulations demonstrated a micron-thick layer   
   of silicon oxide would preserve the efficiency and increase the lifetime   
   of perovskite solar cells in space. As a comparison, the micron-thick   
   layer is about 100 times thinner than a typical human hair.   
      
   Kirmani said the silicon oxide layer could reduce the weight of   
   conventional radiation barriers used for other solar cells by more than   
   99% and serves as a first step toward designing lightweight and low-cost   
   packaging for perovskites.   
      
   High-energy protons travel through perovskite solar cells without causing   
   much harm. Low-energy protons, however, are more abundant in space and   
   wreak more havoc on perovskite cells by knocking atoms out of place   
   and causing efficiency levels to steadily decline. The lower energy   
   protons interact with matter much more readily and the addition of the   
   silicon oxide layer protected the perovskite from damage even from the   
   low-energy protons.   
      
   "We thought it would be impossible for the silicon oxide to provide   
   protection against fully penetrating long-range particles such as the   
   high-energy protons and alpha particles," Kirmani said. "However, the   
   oxide layer turned out to be a surprisingly good barrier against those as   
   well."  The results are detailed in the paper "Metal oxide barrier layers   
   for terrestrial and space perovskite photovoltaics." The co-authors are   
   David Ostrowski, Kaitlyn VanSant, Rosemary Bramante, Karen Heinselman,   
   Jinhui Tong, Bart Stevens, William Nemeth, Kai Zhu, and Joseph Luther,   
   from NREL; and several key collaborators who work with the team from   
   the University of North Texas and the University of Oklahoma. VanSant   
   holds the unique position of being a postdoctoral researcher at NASA   
   who conducts research at NREL.   
      
   Exposure to a stream of low-energy protons caused unprotected perovskite   
   solar cells to lose only about 15% of their initial efficiency, the   
   researchers found. A larger concentration of particles destroyed the   
   cells, while the protected perovskites demonstrated what the scientists   
   described as "a remarkable resilience." With the simple barrier, the   
   cells showed no damage.   
      
   In addition to making the cells more resilient in space, the researchers   
   also tested how the barrier could provide benefit in more conventional   
   applications.   
      
   They then exposed the perovskite solar cells to an uncontrolled   
   moisture and temperature environment for several days to mimic storage   
   conditions. The protected cells retained their initial 19% efficiency,   
   while the unprotected cells showed significant degradation, from 19.4%   
   to 10.8%. The oxide layer also provided protection when other perovskite   
   compositions typically more sensitive to moisture were exposed to water.   
      
   Further, the perovskite solar cells were subjected to a test chamber where   
   they were bombarded with ultraviolet photons similar to the environment   
   at low-Earth orbit. The photons interacted with oxygen to create atomic   
   oxygen. The unprotected cells were destroyed after eight minutes. The   
   protected cells retained their initial efficiency after 20 minutes and   
   only had a slight drop after 30 minutes.   
      
   The simulations and experiments revealed that by reducing the damage   
   from radiation, the lifetime of the protected solar cells used in Earth's   
   orbits and deep space would be increased from months to years.   
      
   "Power conversion efficiency and operational stability of perovskite   
   solar cells have been the two primary focus areas for the community so   
   far," he said.   
      
   "We have made a lot of progress and I think we have come far to the   
   point that we might be pretty close to hitting those targets needed   
   for industrialization.   
      
   However, to really enable this market entry, packaging is the next   
   target."  Because perovskite solar cells can be deposited onto a flexible   
   substrate, the emerging technology, coupled with the protective layer   
   of silicon oxide, allows its use for various terrestrial applications   
   such as powering drones.   
      
   NREL is the U.S. Department of Energy's primary national laboratory for   
   renewable energy and energy efficiency research and development. NREL   
   is operated for DOE by the Alliance for Sustainable Energy LLC.   
      
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   ==========================================================================   
   Story Source: Materials provided by   
   DOE/National_Renewable_Energy_Laboratory. Note: Content may be edited   
   for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Ahmad R. Kirmani, David P. Ostrowski, Kaitlyn T. VanSant, Todd   
      A. Byers,   
         Rosemary C. Bramante, Karen N. Heinselman, Jinhui Tong, Bart   
         Stevens, William Nemeth, Kai Zhu, Ian R. Sellers, Bibhudutta Rout,   
         Joseph M.   
      
         Luther. Metal oxide barrier layers for terrestrial and   
         space perovskite photovoltaics. Nature Energy, 2023; DOI:   
         10.1038/s41560-022-01189-1   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/01/230131183137.htm   
      
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