skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Tolerance Factor and Cooperative Tilting Effects in Vacancy-Ordered Double Perovskite Halides

Abstract

Lattice dynamics and structural instabilities are strongly implicated in dictating the electronic properties of perovskite halide semiconductors. We present a study of the vacancy-ordered double perovskite Rb 2SnI 6 and correlate dynamic and cooperative octahedral tilting with changes in electronic behavior compared to those of Cs 2SnI 6. Though both compounds exhibit native n-type semiconductivity, Rb 2SnI 6 exhibits carrier mobilities that are reduced by a factor of ~50 relative to Cs 2SnI 6. From synchrotron powder X-ray diffraction, we find that Rb 2SnI 6 adopts the tetragonal vacancy-ordered double perovskite structure at room temperature and undergoes a phase transition to a lower-symmetry monoclinic structure upon cooling, characterized by cooperative octahedral tilting of the [SnI6] octahedra. X-ray and neutron pair distribution function analyses reveal that the local coordination environment of Rb 2SnI 6 is consistent with the monoclinic structure at all temperatures; we attribute this observation to dynamic octahedral rotations that become frozen in to yield the low-temperature monoclinic structure. In contrast, Cs 2SnI 6 adopts the cubic vacancy-ordered double perovskite structure at all temperatures. Density functional calculations show that static octahedral tilting in Rb 2SnI 6 results in marginally increased carrier effective masses, which alone are insufficient to accountmore » for the experimental electronic behavior. Rather, the larger number of low-frequency phonons introduced by the lower symmetry of the Rb 2SnI 6 structure yield stronger electron–phonon coupling interactions that produce larger electron effective masses and reduced carrier mobilities relative to Cs 2SnI 6. Further, we discuss the results for Rb 2SnI 6 in the context of other vacancy-ordered double perovskite semiconductors, in order to demonstrate that the electron–phonon coupling characteristics can be predicted using the geometric perovskite tolerance factor. This study represents an important step in designing perovskite halide semiconductors with desired charge transport properties for optoelectronic applications.« less

Authors:
ORCiD logo [1];  [2];  [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Colorado State Univ., Fort Collins, CO (United States). Dept. of Chemistry
  2. Univ. College London (United Kingdom). Kathleen Lonsdale Materials Chemistry. Dept. of Chemistry. Thomas Young Centre; Science and Technology Facilities Council (STFC), Harwell Campus, Didcot (United Kingdom). Diamond Light Source, Ltd.
Publication Date:
Research Org.:
Colorado State Univ., Fort Collins, CO (United States); Univ. College London (United Kingdom)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Engineering and Physical Sciences Research Council (EPSRC)
OSTI Identifier:
1457590
Alternate Identifier(s):
OSTI ID: 1499116
Grant/Contract Number:  
SC0016083; AC02-06CH11357; EP/L000202; EP/N01572X/1; EP/L015862/1
Resource Type:
Published Article
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 30; Journal Issue: 11; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE

Citation Formats

Maughan, Annalise E., Ganose, Alex M., Almaker, Mohammed A., Scanlon, David O., and Neilson, James R. Tolerance Factor and Cooperative Tilting Effects in Vacancy-Ordered Double Perovskite Halides. United States: N. p., 2018. Web. doi:10.1021/acs.chemmater.8b01549.
Maughan, Annalise E., Ganose, Alex M., Almaker, Mohammed A., Scanlon, David O., & Neilson, James R. Tolerance Factor and Cooperative Tilting Effects in Vacancy-Ordered Double Perovskite Halides. United States. doi:10.1021/acs.chemmater.8b01549.
Maughan, Annalise E., Ganose, Alex M., Almaker, Mohammed A., Scanlon, David O., and Neilson, James R. Wed . "Tolerance Factor and Cooperative Tilting Effects in Vacancy-Ordered Double Perovskite Halides". United States. doi:10.1021/acs.chemmater.8b01549.
@article{osti_1457590,
title = {Tolerance Factor and Cooperative Tilting Effects in Vacancy-Ordered Double Perovskite Halides},
author = {Maughan, Annalise E. and Ganose, Alex M. and Almaker, Mohammed A. and Scanlon, David O. and Neilson, James R.},
abstractNote = {Lattice dynamics and structural instabilities are strongly implicated in dictating the electronic properties of perovskite halide semiconductors. We present a study of the vacancy-ordered double perovskite Rb2SnI6 and correlate dynamic and cooperative octahedral tilting with changes in electronic behavior compared to those of Cs2SnI6. Though both compounds exhibit native n-type semiconductivity, Rb2SnI6 exhibits carrier mobilities that are reduced by a factor of ~50 relative to Cs2SnI6. From synchrotron powder X-ray diffraction, we find that Rb2SnI6 adopts the tetragonal vacancy-ordered double perovskite structure at room temperature and undergoes a phase transition to a lower-symmetry monoclinic structure upon cooling, characterized by cooperative octahedral tilting of the [SnI6] octahedra. X-ray and neutron pair distribution function analyses reveal that the local coordination environment of Rb2SnI6 is consistent with the monoclinic structure at all temperatures; we attribute this observation to dynamic octahedral rotations that become frozen in to yield the low-temperature monoclinic structure. In contrast, Cs2SnI6 adopts the cubic vacancy-ordered double perovskite structure at all temperatures. Density functional calculations show that static octahedral tilting in Rb2SnI6 results in marginally increased carrier effective masses, which alone are insufficient to account for the experimental electronic behavior. Rather, the larger number of low-frequency phonons introduced by the lower symmetry of the Rb2SnI6 structure yield stronger electron–phonon coupling interactions that produce larger electron effective masses and reduced carrier mobilities relative to Cs2SnI6. Further, we discuss the results for Rb2SnI6 in the context of other vacancy-ordered double perovskite semiconductors, in order to demonstrate that the electron–phonon coupling characteristics can be predicted using the geometric perovskite tolerance factor. This study represents an important step in designing perovskite halide semiconductors with desired charge transport properties for optoelectronic applications.},
doi = {10.1021/acs.chemmater.8b01549},
journal = {Chemistry of Materials},
number = 11,
volume = 30,
place = {United States},
year = {2018},
month = {5}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1021/acs.chemmater.8b01549

Figures / Tables:

Figure 1 Figure 1: Crystal structures of Rb2SnI6 at T = 295 K and T = 100 K. In (a) and (c), the structures are projected down the c-axis to highlight the octahedral tilting and rotation, while unit cell descriptions are shown in (b) and (d). Rubidium atoms are shown in pink,more » tin atoms in blue, and iodine atoms in purple.« less

Save / Share:

Works referencing / citing this record:

Two-dimensional lead-free iodide-based hybrid double perovskites: crystal growth, thin-film preparation and photocurrent responses
journal, January 2019

  • Bi, Le-Yu; Hu, Yue-Qiao; Li, Mu-Qing
  • Journal of Materials Chemistry A, Vol. 7, Issue 34
  • DOI: 10.1039/c9ta04325j