Origin of Long Lifetime of Band-Edge Charge Carriers in Organic-Inorganic Lead Iodide Perovskites

ORAL

Abstract

Long carrier lifetime is what makes hybrid organic-inorganic perovskites high performance photovoltaic materials. Several microscopic mechanisms behind the unusually long carrier lifetime have been proposed, such as formation of large polarons, Rashba effect, ferroelectric domains, and photon recycling. Here, we show that the screening of band-edge charge carriers by rotation of organic cation molecules can be a major contribution to the prolonged carrier lifetime. Our results reveal that the band-edge carrier lifetime increases when the system enters from a phase with lower rotational entropy to another phase with higher entropy. These results imply that the recombination of the photo-excited electrons and holes is suppressed by the screening, leading to the formation of polarons and thereby extending the lifetime. Thus, searching for organic-inorganic perovskites with high rotational entropy over a wide range of temperature may be a key to achieve superior solar cell performance.[1]
[1] T. Chen et al., Proceedings of the National Academy of Sciences 114, 7519-7524, (2017).

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Presenters

  • Tianran Chen

    University of Virginia, Department of Physics, University of Virginia

Authors

  • Tianran Chen

    University of Virginia, Department of Physics, University of Virginia

  • Wei-Liang Chen

    National Taiwan University, Center for Condensed Matter Sciences, National Taiwan University

  • Benjamin Foley

    Department of Chemical Engineering, University of Virginia

  • Jooseop Lee

    Cornell High Energy Synchrotron Source, Cornell University

  • Jacob Ruff

    CHESS, NIST Center for Neutron Research, National Institute of Standards and Technology, Cornell High Energy Synchrotron Source, Cornell University

  • J. Y. Peter Ko

    Cornell High Energy Synchrotron Source, Cornell University

  • Craig Brown

    NCNR, NIST, National Institute of Standards and Technology, NIST Center for Neutron Research, National Institute of Standards and Technology

  • Leland Harriger

    NIST Center for Neutron Research, NCNR, NIST, National Institute of Standards and Technology, NIST Center for Neutron Research, National Institute of Standards and Technology, NIST center for Neutron Scattering

  • Depei Zhang

    University of Virginia, Department of Physics, University of Virginia

  • Changwon Park

    Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Department of Physics and Astronomy, University of Tennessee, Knoxville

  • Mina Yoon

    Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge National Laboratory

  • Yu-Ming Chang

    Center for Condensed Matter Sciences, National Taiwan University

  • Joshua Choi

    University of Virginia, Department of Chemical Engineering, University of Virginia

  • Seunghun Lee

    University of Virginia, Department of Physics, University of Virginia