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Title: Defect Tolerance to Intolerance in the Vacancy-Ordered Double Perovskite Semiconductors Cs 2 SnI 6 and Cs 2 TeI 6

Abstract

Vacancy-ordered double perovskites of the general formula, A2BX6, are a family of perovskite derivatives composed of a face-centered lattice of nearly isolated [BX6] units with A-site cations occupying the cuboctahedral voids. Despite the presence of isolated octahedral units, the close-packed iodide lattice provides significant electronic dispersion, such that Cs2SnI6 has recently been explored for applications in photovoltaic devices. To elucidate the structure-property relationships of these materials, we have synthesized the solid solution Cs2Sn1-xTexI6. However, even though tellurium substitution increases electronic dispersion via closer I-I contact distances, the substitution experimentally yields insulating behavior from a significant decrease in carrier concentration and mobility. Density functional calculations of native defects in Cs2SnI6 reveal that iodine vacancies exhibit a low enthalpy of formation and the defect energy level is a shallow donor to the conduction band, rendering the material tolerant to these defect states. The increased covalency of Te-I bonding renders the formation of iodine vacancy states unfavorable, and is responsible for the reduction in conductivity upon Te substitution. Additionally, Cs2TeI6 is intolerant to the formation of these defects, as the defect level occurs deep within the band gap and thus localizes potential mobile charge carriers. In these vacancy-ordered double perovskites, the close-packed latticemore » of iodine provides significant electronic dispersion, while the interaction of the B- and X-site ions dictates the properties as they pertain to electronic structure and defect tolerance. This simplified perspective -- based on extensive experimental and theoretical analysis -- provides a platform from which to understand structure-property relationships in functional perovskite halides.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1271938
Report Number(s):
NREL/JA-5900-66686
Journal ID: ISSN 0002-7863
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 138; Journal Issue: 27; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; perovskites; defect tolerance

Citation Formats

Maughan, Annalise E., Ganose, Alex M., Bordelon, Mitchell M., Miller, Elisa M., Scanlon, David O., and Neilson, James R.. Defect Tolerance to Intolerance in the Vacancy-Ordered Double Perovskite Semiconductors Cs 2 SnI 6 and Cs 2 TeI 6. United States: N. p., 2016. Web. doi:10.1021/jacs.6b03207.
Maughan, Annalise E., Ganose, Alex M., Bordelon, Mitchell M., Miller, Elisa M., Scanlon, David O., & Neilson, James R.. Defect Tolerance to Intolerance in the Vacancy-Ordered Double Perovskite Semiconductors Cs 2 SnI 6 and Cs 2 TeI 6. United States. doi:10.1021/jacs.6b03207.
Maughan, Annalise E., Ganose, Alex M., Bordelon, Mitchell M., Miller, Elisa M., Scanlon, David O., and Neilson, James R.. Wed . "Defect Tolerance to Intolerance in the Vacancy-Ordered Double Perovskite Semiconductors Cs 2 SnI 6 and Cs 2 TeI 6". United States. doi:10.1021/jacs.6b03207.
@article{osti_1271938,
title = {Defect Tolerance to Intolerance in the Vacancy-Ordered Double Perovskite Semiconductors Cs 2 SnI 6 and Cs 2 TeI 6},
author = {Maughan, Annalise E. and Ganose, Alex M. and Bordelon, Mitchell M. and Miller, Elisa M. and Scanlon, David O. and Neilson, James R.},
abstractNote = {Vacancy-ordered double perovskites of the general formula, A2BX6, are a family of perovskite derivatives composed of a face-centered lattice of nearly isolated [BX6] units with A-site cations occupying the cuboctahedral voids. Despite the presence of isolated octahedral units, the close-packed iodide lattice provides significant electronic dispersion, such that Cs2SnI6 has recently been explored for applications in photovoltaic devices. To elucidate the structure-property relationships of these materials, we have synthesized the solid solution Cs2Sn1-xTexI6. However, even though tellurium substitution increases electronic dispersion via closer I-I contact distances, the substitution experimentally yields insulating behavior from a significant decrease in carrier concentration and mobility. Density functional calculations of native defects in Cs2SnI6 reveal that iodine vacancies exhibit a low enthalpy of formation and the defect energy level is a shallow donor to the conduction band, rendering the material tolerant to these defect states. The increased covalency of Te-I bonding renders the formation of iodine vacancy states unfavorable, and is responsible for the reduction in conductivity upon Te substitution. Additionally, Cs2TeI6 is intolerant to the formation of these defects, as the defect level occurs deep within the band gap and thus localizes potential mobile charge carriers. In these vacancy-ordered double perovskites, the close-packed lattice of iodine provides significant electronic dispersion, while the interaction of the B- and X-site ions dictates the properties as they pertain to electronic structure and defect tolerance. This simplified perspective -- based on extensive experimental and theoretical analysis -- provides a platform from which to understand structure-property relationships in functional perovskite halides.},
doi = {10.1021/jacs.6b03207},
journal = {Journal of the American Chemical Society},
issn = {0002-7863},
number = 27,
volume = 138,
place = {United States},
year = {2016},
month = {7}
}