Two-dimensional overdamped fluctuations of soft perovskite lattice in CsPbBr<sub>3</sub>

ORAL

Abstract

Lead halide perovskites exhibit structural instabilities and large atomic fluctuations thought to impact their optical and thermal properties, yet detailed structural and temporal correlations of their atomic motions remain poorly understood. Here, these correlations are resolved in CsPbBr3 crystals using momentum-resolved neutron and x-ray scattering measurements as a function of temperature, complemented with first-principles simulations. We uncover a striking network of diffuse scattering rods, arising from the liquid-like damping of low-energy Br-dominated phonons, reproduced in our simulations of the anharmonic phonon self-energy. These overdamped modes cover a continuum of wave vectors along the edges of the cubic Brillouin zone, corresponding to two-dimensional (2D) sheets of correlated rotations in real space, and could represent precursors to proposed 2D polarons. Further, these motions directly impact the electronic gap edge states, linking soft anharmonic lattice dynamics and optoelectronic properties. These results provide new insights into the highly unusual atomic dynamics of halide perovskites, relevant to further optimize their optical and thermal properties.

*U.S. DOE, Office of Science, BES, Materials Sciences and Engineering Division, Award No. DE-SC0019299.

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Presenters

  • Tyson Lanigan-Atkins

    • Mechanical Engineering and Materials Science, Duke University
    • Duke University

Authors

  • Tyson Lanigan-Atkins

    • Mechanical Engineering and Materials Science, Duke University
    • Duke University

  • Xing He

    • Duke University

  • Matthew Krogstad

    • Materials Science Division, Argonne National Laboratory
    • Argonne National Laboratory
    • Materials Science Division, Argonne National Lab
    • Material Science, Argonne National Laboratory
    • Material Science Division, Argonne National Laboratory

  • Daniel Pajerowski

    • Neutron Scattering Division, Oak Ridge National Laboratory

  • Douglas L Abernathy

    • Neutron Scattering Division, Oak Ridge National Laboratory
    • Oak Ridge National Laboratory
    • Oak Ridge National Lab

  • Guangyong Xu

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

  • Zhijun Xu

    • National Institute of Standards and Technology
    • NIST and University of Maryland
    • NIST Center for Neutron research, National Institute of Standards and Technology
    • NIST Center for Neutron Research
    • University of Maryland
    • NIST Center for Neutron Research, NIST

  • Duck Young Chung

    • Argonne National Laboratory
    • Materials Science Division, Argonne National Laboratory

  • Mercouri Kanatzidis

    • Chemistry, Northwestern University
    • Argonne National Laboratory
    • Northwestern University
    • Chemistry Department, Northwestern University

  • Stephan Rosenkranz

    • Materials Science Division, Argonne National Laboratory
    • Argonne National Laboratory
    • Materials Science Division, Argonne National Lab
    • Materials Science, Argonne National Laboratory
    • Material Science, Argonne National Laboratory
    • Material Science Division, Argonne National Laboratory

  • Raymond Osborn

    • Materials Science Division, Argonne National Laboratory
    • Argonne National Laboratory
    • Materials Science Division, Argonne National Lab
    • Materials Science, Argonne National Laboratory
    • Material Science, Argonne National Laboratory
    • Material Science Division, Argonne National Laboratory

  • Olivier Delaire

    • Department of Mechanical Engineering and Materials Science, Duke University
    • Duke University
    • duke university
    • Mechanical Engineering and Materials Science, Duke University