Electron−hole separation in ferroelectric oxides for efficient photovoltaic responses
Name
1721503115.full.pdf
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2.47 MB
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Checksum (MD5)
07506469866b54288b91765df4c4c503
Author(s)
Kim, Donghoon
Han, Hyeon
Lee, June Ho
Choi, Jin Woo
Grossman, Jeffrey C.
Jang, Hyun Myung
Kim, Donghun
Date Issued
May 2018
Journal
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences (U.S.)
Citation
Kim, Donghoon et al. “Electron−hole Separation in Ferroelectric Oxides for Efficient Photovoltaic Responses.” Proceedings of the National Academy of Sciences 115, 26 (June 2018): 6566–6571 © 2018 National Academy of Sciences
Version
Final published version
Abstract
Despite their potential to exceed the theoretical Shockley−Queisser limit, ferroelectric photovoltaics (FPVs) have performed inefficiently due to their extremely low photocurrents. Incorporating Bi₂FeCrO₆(BFCO) as the light absorber in FPVs has recently led to impressively high and record photocurrents [Nechache R, et al. (2015) Nat Photonics 9:61–67], which has revived the FPV field. However, our understanding of this remarkable phenomenon is far from satisfactory. Here, we use first-principles calculations to determine that such excellent performance mainly lies in the efficient separation of electron− hole (e-h) pairs. We show that photoexcited electrons and holes in BFCO are spatially separated on the Fe and Cr sites, respectively. This separation is much more pronounced in disordered BFCO phases, which adequately explains the observed exceptional PV responses. We further establish a design strategy to discover next-generation FPV materials. By exploring 44 additional Bi-based double-perovskite oxides, we suggest five active-layer materials that offer a combination of strong e-h separations and visible-light absorptions for FPV applications. Our work indicates that charge separation is the most important issue to be addressed for FPVs to compete with conventional devices. Keywords: ferroelectrics; double perovskites; photovoltaics; e-h separation; density functional theory
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
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DOI of Published Version
https://doi.org/10.1073/PNAS.1721503115
