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Title: Shallow halogen vacancies in halide optoelectronic materials

Halogen vacancies (VH) are usually deep color centers (F centers) in halides and can act as major electron traps or recombination centers. The deep VH contributes to the typically poor carrier transport properties in halides. However, several halides have recently emerged as excellent optoelectronic materials, e.g., CH3NH3PbI3 and TlBr. Both CH3NH3PbI3 and TlBr have been found to have shallow VH, in contrast to commonly seen deep VH in halides. In this paper, several halide optoelectronic materials, i.e., CH3NH3PbI3, CH3NH3SnI3 (photovoltaic materials), TlBr, and CsPbBr3, (gamma-ray detection materials) are studied to understand the material chemistry and structure that determine whether VH is a shallow or deep defect in a halide material. It is found that crystal structure and chemistry of ns2 ions both play important roles in creating shallow VH in halides such as CH3NH3PbI3, CH3NH3SnI3, and TlBr. The key to identifying halides with shallow VH is to find the right crystal structures and compounds that suppress cation orbital hybridization at VH, such as those with long cation-cation distances and low anion coordination numbers, and those with crystal symmetry that prevents strong hybridization of cation dangling bond orbitals at VH. Furthermore, the results of this paper provide insight and guidance tomore » identifying halides with shallow VH as good electronic and optoelectronic materials.« less
Authors:
 [1] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division
Publication Date:
OSTI Identifier:
1185671
Grant/Contract Number:
AC05-00OR22725; HSHQDC-14-R-B0009
Type:
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 90; Journal Issue: 17; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Department of Homeland Security (DHS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE