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The nature of dynamic local order in CH3NH3PbI3 and CH3NH3PbBr3

  • Nicholas J. Weadock
  • , Tyler C. Sterling
  • , Julian A. Vigil
  • , Aryeh Gold-Parker
  • , Ian C. Smith
  • , Ballal Ahammed
  • , Matthew J. Krogstad
  • , Feng Ye
  • , David Voneshen
  • , Peter M. Gehring
  • , Andrew M. Rappe
  • , Hans Georg Steinrück
  • , Elif Ertekin
  • , Hemamala I. Karunadasa
  • , Dmitry Reznik
  • , Michael F. Toney

Research output: Contribution to journalArticlepeer-review

Abstract

Hybrid lead-halide perovskites (LHPs) are semiconductors with novel properties that are distinctively governed by structural fluctuations. Diffraction experiments sensitive to long-range order reveal a cubic structure in the device-relevant, high-temperature phase. Local probes find additional short-range order with lower symmetry that may govern structure-function relationships. However, our understanding is impeded by unresolved dimensionality, participating atoms, and dynamics of short-range order. Here, we determine the true structure of two hybrid LHPs, CH3NH3PbI3 and CH3NH3PbBr3, using a combination of single-crystal diffuse scattering, neutron inelastic spectroscopy, and molecular dynamics simulations. The remarkable collective dynamics, not observed in previous studies, consist of a network of local, two-dimensional, circular regions of dynamically tilting lead-halide octahedra (lower symmetry) that induce longer-range intermolecular CH3NH3+ correlations. The dynamic local structure may introduce transient ferroelectric or antiferroelectric domains that increase charge carrier lifetimes and strongly affect halide migration, a poorly understood degradation mechanism.

Original languageEnglish (US)
Pages (from-to)1051-1066
Number of pages16
JournalJoule
Volume7
Issue number5
DOIs
StatePublished - May 17 2023

Keywords

  • diffuse scattering
  • ion migration
  • local structure
  • metal halide perovskites
  • molecular dynamics simulations

ASJC Scopus subject areas

  • General Energy

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