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Title: Orientational Glass Formation in Substituted Hybrid Perovskites

Hybrid organic-inorganic perovskites have gained notoriety in the photovoltaic community for their composition-tunable band gaps and long-lived electronic excited states, which are known to be related to the crystalline phase. While indirect evidence suggests that coupling between polar organic cations affects the phase behavior, it remains unclear how the coupling manifests in hybrid perovskites such as methylammonium lead halides (CH 3NH 3PbX 3). Here, we present crystallographic and spectroscopic data for the series (CH 3NH 3) 1-xCs xPbBr 3. CH 3NH 3PbBr 3 behaves as a plastic crystal in the high temperature cubic phase, and substitution of CH 3NH 3 + with Cs + leads to the formation of an orientational glass. While the organic molecule exhibits slow, glassy reorientational dynamics, the inorganic framework continues to undergo crystallographic phase transitions. These crystallographic transitions occur in the absence of thermodynamic signatures in the specific heat, which suggests that the phase transitions result from underlying instabilities intrinsic to the inorganic lattice. However, these transitions are not decoupled from the reorientations of the organic molecule, as indicated by inelastic and quasielastic neutron scattering. Observation of a reentrant phase transition in (CH 3NH 3) 0.8Cs 0.2PbBr 3 permits the resolution of these complex behaviorsmore » within the context of strain mediated interactions. Lastly, together, these results provide critical insight into the coupled phase behavior and dynamics in hybrid perovskites.« less
Authors:
ORCiD logo [1] ;  [1] ;  [2] ;  [2] ; ORCiD logo [3] ;  [2] ; ORCiD logo [1]
  1. Colorado State Univ., Fort Collins, CO (United States). Dept. of Chemistry
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Scattering Division
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Scattering Division; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS) outstation Juelich Centre for Neutron Science (JCNS), Forschungszentrum Juelich GmbH
Publication Date:
Grant/Contract Number:
SC0016083; AC02-06CH11357; AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 23; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Research Org:
Colorado State Univ., Fort Collins, CO (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE
OSTI Identifier:
1410797
Alternate Identifier(s):
OSTI ID: 1440822

Mozur, Eve M., Maughan, Annalise E., Cheng, Yongqiang, Huq, Ashfia, Jalarvo, Niina, Daemen, Luke L., and Neilson, James R.. Orientational Glass Formation in Substituted Hybrid Perovskites. United States: N. p., Web. doi:10.1021/acs.chemmater.7b04017.
Mozur, Eve M., Maughan, Annalise E., Cheng, Yongqiang, Huq, Ashfia, Jalarvo, Niina, Daemen, Luke L., & Neilson, James R.. Orientational Glass Formation in Substituted Hybrid Perovskites. United States. doi:10.1021/acs.chemmater.7b04017.
Mozur, Eve M., Maughan, Annalise E., Cheng, Yongqiang, Huq, Ashfia, Jalarvo, Niina, Daemen, Luke L., and Neilson, James R.. 2017. "Orientational Glass Formation in Substituted Hybrid Perovskites". United States. doi:10.1021/acs.chemmater.7b04017. https://www.osti.gov/servlets/purl/1410797.
@article{osti_1410797,
title = {Orientational Glass Formation in Substituted Hybrid Perovskites},
author = {Mozur, Eve M. and Maughan, Annalise E. and Cheng, Yongqiang and Huq, Ashfia and Jalarvo, Niina and Daemen, Luke L. and Neilson, James R.},
abstractNote = {Hybrid organic-inorganic perovskites have gained notoriety in the photovoltaic community for their composition-tunable band gaps and long-lived electronic excited states, which are known to be related to the crystalline phase. While indirect evidence suggests that coupling between polar organic cations affects the phase behavior, it remains unclear how the coupling manifests in hybrid perovskites such as methylammonium lead halides (CH3NH3PbX3). Here, we present crystallographic and spectroscopic data for the series (CH3NH3)1-xCsxPbBr3. CH3NH3PbBr3 behaves as a plastic crystal in the high temperature cubic phase, and substitution of CH3NH3+ with Cs+ leads to the formation of an orientational glass. While the organic molecule exhibits slow, glassy reorientational dynamics, the inorganic framework continues to undergo crystallographic phase transitions. These crystallographic transitions occur in the absence of thermodynamic signatures in the specific heat, which suggests that the phase transitions result from underlying instabilities intrinsic to the inorganic lattice. However, these transitions are not decoupled from the reorientations of the organic molecule, as indicated by inelastic and quasielastic neutron scattering. Observation of a reentrant phase transition in (CH3NH3)0.8Cs0.2PbBr3 permits the resolution of these complex behaviors within the context of strain mediated interactions. Lastly, together, these results provide critical insight into the coupled phase behavior and dynamics in hybrid perovskites.},
doi = {10.1021/acs.chemmater.7b04017},
journal = {Chemistry of Materials},
number = 23,
volume = 29,
place = {United States},
year = {2017},
month = {11}
}