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Title: Direct Observation of Halide Migration and its Effect on the Photoluminescence of Methylammonium Lead Bromide Perovskite Single Crystals

Optoelectronic devices based on hybrid perovskites have demonstrated outstanding performance within a few years of intense study. However, commercialization of these devices requires barriers to their development to be overcome, such as their chemical instability under operating conditions. In order to investigate this instability and its consequences, the electric field applied to single crystals of methylammonium lead bromide (CH 3NH 3PbBr 3) is varied, and changes are mapped in both their elemental composition and photo-luminescence. Synchrotron-based nanoprobe X-ray fluorescence (nano-XRF) with 250 nm resolution reveals quasi-reversible field-assisted halide migration, with corresponding changes in photoluminescence. It is observed that higher local bromide concentration is correlated to superior optoelectronic performance in CH 3NH 3PbBr 3. A lower limit on the electromigration rate is calculated from these experiments and the motion is interpreted as vacancy-mediated migration based on nudged elastic band density functional theory (DFT) simulations. The XRF mapping data provide direct evidence of field-assisted ionic migration in a model hybrid-perovskite thin single crystal, while the link with photoluminescence proves that the halide stoichiometry plays a key role in the optoelectronic properties of the perovskite.
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [2] ; ORCiD logo [1]
  1. Univ. of California, San Diego, CA (United States). Dept. of Nanoengineering
  2. FOM Inst. for Atomic and Molecular Physics (AMOLF), Amsterdam (Netherlands). Center for Nanophotonics
  3. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Publication Date:
Grant/Contract Number:
AC02-06CH11357; FP/2007‐2013; 337328; SC0012118; ACI‐1053575
Type:
Accepted Manuscript
Journal Name:
Advanced Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 43; Journal ID: ISSN 0935-9648
Publisher:
Wiley
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; Netherlands Organization for Scientific Research (NWO); European Research Council (ERC); Koninklijke Philips N.V., Amsterdam (Netherlands); National Science Foundation (NSF)
Contributing Orgs:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; nudged elastic band (NEB); DFT computation; halide migration; hybrid perovskites; nanoprobe x-ray fluorescence; spatially resolved photoluminescence mapping
OSTI Identifier:
1468624
Alternate Identifier(s):
OSTI ID: 1395604