Two-Dimensional Overdamped Fluctuations of the Soft Perovskite Lattice in CsPbBr3

Published

July 1, 2021

Author(s)

T. Lanigan-Atkins, X. He, M. Krogstad, D. M. Pajerowski, D. Abernathy, Guangyong Xu, Zhijun Xu, D.-Y. Chung, M. G. Kanatzidis, S. Rosenkranz, R. Osborn, O. Delaire

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 extended diffuse scattering signal, arising from the liquid-like damping of low-energy. These overdamped modes occur over a continuum of wave vectors along rods spanning the edges of the cubic Brillouin zone, corresponding to two-dimensional (2D) sheets of correlated rotations in real space, akin to proposed 2D polarons in this system. Further, these motions directly impact the electronic gap edges 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.

Citation

Nature Materials

Volume

20

Pub Type

Journals

Keywords

neutron scattering, two-dimensional, perovskite

Citation

Lanigan-Atkins, T. , He, X. , Krogstad, M. , Pajerowski, D. , Abernathy, D. , Xu, G. , Xu, Z. , Chung, D. , Kanatzidis, M. , Rosenkranz, S. , Osborn, R. and Delaire, O. (2021), Two-Dimensional Overdamped Fluctuations of the Soft Perovskite Lattice in CsPbBr₃, Nature Materials (Accessed April 26, 2024)