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  4. Axial-Equatorial Halide Ordering in Layered Hybrid Perovskites from Isotropic-Anisotropic 207Pb NMR
 
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research article

Axial-Equatorial Halide Ordering in Layered Hybrid Perovskites from Isotropic-Anisotropic 207Pb NMR

Hope, Michael Allan  
•
Cordova, Manuel  
•
Mishra, Aditya  
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February 19, 2024
Angewandte Chemie International Edition

Bandgap-tuneable mixed-halide 3D perovskites are of interest for multi-junction solar cells, but suffer from photoinduced spatial halide segregation. Mixed-halide 2D perovskites are more resistant to halide segregation and are promising coatings for 3D perovskite solar cells. The properties of mixed-halide compositions depend on the local halide distribution, which is challenging to study at the level of single octahedra. In particular, it has been suggested that there is a preference for occupation of the distinct axial and equatorial halide sites in mixed-halide 2D perovskites. Pb-207 NMR can be used to probe the atomic-scale structure of lead-halide materials, but although the isotropic Pb-207 shift is sensitive to halide stoichiometry, it cannot distinguish configurational isomers. Here, we use 2D isotropic-anisotropic correlation 207Pb NMR and relativistic DFT calculations to distinguish the [PbX6] configurations in mixed iodide-bromide 3D FAPb(Br1-xIx)(3) perovskites and 2D BA(2)Pb(Br1-xIx)(4) perovskites based on formamidinium (FA(+)) and butylammonium (BA(+)), respectively. We find that iodide preferentially occupies the axial site in BA-based 2D perovskites, which may explain the suppressed halide mobility.

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Type
research article
DOI
10.1002/anie.202314856
Web of Science ID

WOS:001165453500001

Author(s)
Hope, Michael Allan  
•
Cordova, Manuel  
•
Mishra, Aditya  
•
Gunes, Ummugulsum  
•
Caiazzo, Alessandro
•
Datta, Kunal
•
Janssen, Rene A. J.
•
Emsley, Lyndon  
Date Issued

2024-02-19

Publisher

Wiley-VCH Verlag GmbH

Published in
Angewandte Chemie International Edition
Subjects

Physical Sciences

•

Ab Initio Calculations

•

2D Halide Perovskites

•

Halide Segregation

•

Nmr Spectroscopy

•

Photovoltaic Materials

Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LRM  
FunderGrant Number

SNSF

200020_212046

H2020 Marie Sklodowska-Curie Individual fellowship

101024144

Ecole Polytechnique Federale de Lausanne

Available on Infoscience
March 18, 2024
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/206447
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