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Title: Instability and efficiency of mixed halide perovskites CH 3NH 3AI 3-xCl x (A = Pb and Sn): A first-principles, computational study

Here, we carried out calculations based on density functional theory to investigate the electronic, vibrational, and dielectric properties of mixed halide perovskites CH 3NH 3AI 3–xCl x with A = Pb and Sn. Computed free energies indicated that Cl mixed systems may be formed only for Cl concentrations not exceeding 10 19 cm –3, and phonon calculations showed that the disorder induced in the host lattice by the presence of a smaller halogen is responsible for mechanical instabilities. However, we found that the presence of chloride may be beneficial to the electronic properties of the perovskites. Chloride anions cause the organic cations to be displaced from the center of the cage; such a displacement induces preferential orientations of the cation dipole, which in turn are responsible for notable changes in the dielectric properties of the material and possibly for the formation of local ferroelectric domains. The latter are instrumental in separating electron hole pairs and hence in contributing to long charge-carrier diffusion lengths, in spite of polarons being more likely formed in mixed perovksites than in CH 3NH 3AI 3.
Authors:
ORCiD logo [1] ;  [2]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
  2. The Univ. of Chicago, Chicago, IL (United States); Argonne National Lab. (ANL), Lemont, IL (United States)
Publication Date:
Report Number(s):
SAND-2016-10228J
Journal ID: ISSN 0897-4756; 648215; TRN: US1701150
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 2; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Research Org:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1340523

He, Yuping, and Galli, Giulia. Instability and efficiency of mixed halide perovskites CH3NH3AI3-xClx (A = Pb and Sn): A first-principles, computational study. United States: N. p., Web. doi:10.1021/acs.chemmater.6b04300.
He, Yuping, & Galli, Giulia. Instability and efficiency of mixed halide perovskites CH3NH3AI3-xClx (A = Pb and Sn): A first-principles, computational study. United States. doi:10.1021/acs.chemmater.6b04300.
He, Yuping, and Galli, Giulia. 2016. "Instability and efficiency of mixed halide perovskites CH3NH3AI3-xClx (A = Pb and Sn): A first-principles, computational study". United States. doi:10.1021/acs.chemmater.6b04300. https://www.osti.gov/servlets/purl/1340523.
@article{osti_1340523,
title = {Instability and efficiency of mixed halide perovskites CH3NH3AI3-xClx (A = Pb and Sn): A first-principles, computational study},
author = {He, Yuping and Galli, Giulia},
abstractNote = {Here, we carried out calculations based on density functional theory to investigate the electronic, vibrational, and dielectric properties of mixed halide perovskites CH3NH3AI3–xClx with A = Pb and Sn. Computed free energies indicated that Cl mixed systems may be formed only for Cl concentrations not exceeding 1019 cm–3, and phonon calculations showed that the disorder induced in the host lattice by the presence of a smaller halogen is responsible for mechanical instabilities. However, we found that the presence of chloride may be beneficial to the electronic properties of the perovskites. Chloride anions cause the organic cations to be displaced from the center of the cage; such a displacement induces preferential orientations of the cation dipole, which in turn are responsible for notable changes in the dielectric properties of the material and possibly for the formation of local ferroelectric domains. The latter are instrumental in separating electron hole pairs and hence in contributing to long charge-carrier diffusion lengths, in spite of polarons being more likely formed in mixed perovksites than in CH3NH3AI3.},
doi = {10.1021/acs.chemmater.6b04300},
journal = {Chemistry of Materials},
number = 2,
volume = 29,
place = {United States},
year = {2016},
month = {12}
}