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Title: Local polar fluctuations in lead halide perovskite crystals

Hybrid lead-halide perovskites have emerged as an excellent class of photovoltaic materials. Recent reports suggest that the organic molecular cation is responsible for local polar fluctuations that inhibit carrier recombination. We combine low-frequency Raman scattering with first-principles molecular dynamics (MD) to study the fundamental nature of these local polar fluctuations. Our observations of a strong central peak in the cubic phase of both hybrid (CH 3NH 3PbBr 3) and all-inorganic (CsPbBr 3) lead-halide perovskites show that anharmonic, local polar fluctuations are intrinsic to the general lead-halide perovskite structure, and not unique to the dipolar organic cation. Furthermore, MD simulations indicate that head-to-head Cs motion coupled to Br face expansion, occurring on a few hundred femtosecond time scale, drives the local polar fluctuations in CsPbBr 3.
 [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [4] ;  [2] ;  [5] ;  [3] ;  [6] ;  [1] ;  [2] ;  [7] ;  [1]
  1. Columbia Univ., New York, NY (United States)
  2. Univ. of Pennsylvania, Philadelphia, PA (United States)
  3. Weizmann Institute of Science, Rehovoth (Israel)
  4. Argonne National Lab. (ANL), Argonne, IL (United States)
  5. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  6. Argonne National Lab. (ANL), Argonne, IL (United States); Northwestern Univ., Evanston, IL (United States)
  7. Columbia Univ., New York, NY (United States); Univ. Federal de Minas Gerais, Belo Horizonte (Brazil)
Publication Date:
Grant/Contract Number:
SC0001085; IOF-622653; N00014-14-1-0761; N00014-12-1-1033; FG02-07ER46431; J3608-N20; NA0002522; AC02-76SF00515
Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 118; Journal Issue: 13; Journal ID: ISSN 0031-9007
American Physical Society (APS)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
74 ATOMIC AND MOLECULAR PHYSICS; 36 MATERIALS SCIENCE; local polar fluctuations; hybrid perovskites; low frequency Raman scattering; molecular dynamics; radiation detection; Central peak
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1349148