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Phase segregation in mixed-halide perovskites affects charge-carrier dynamics while preserving mobility

Abstract:
Mixed halide perovskites can provide optimal bandgaps for tandem solar cells which are key to improved cost-efficiencies, but can still suffer from detrimental illumination-induced phase segregation. Here we employ optical-pump terahertz-probe spectroscopy to investigate the impact of halide segregation on the charge-carrier dynamics and transport properties of mixed halide perovskite films. We reveal that, surprisingly, halide segregation results in negligible impact to the THz charge-carrier mobilities, and that charge carriers within the I-rich phase are not strongly localised. We further demonstrate enhanced lattice anharmonicity in the segregated I-rich domains, which is likely to support ionic migration. These phonon anharmonicity effects also serve as evidence of a remarkably fast, picosecond charge funnelling into the narrow-bandgap I-rich domains. Our analysis demonstrates how minimal structural transformations during phase segregation have a dramatic effect on the charge-carrier dynamics as a result of charge funnelling. We suggest that because such enhanced recombination is radiative, performance losses may be mitigated by deployment of careful light management strategies in solar cells.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1038/s41467-021-26930-4

Authors


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Role:
Author
ORCID:
0000-0002-8088-3485
More by this author
Role:
Author
ORCID:
0000-0001-5132-1232
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Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Oxford college:
St Anne's College
Role:
Author
ORCID:
0000-0003-4980-7940
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Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Condensed Matter Physics
Role:
Author
ORCID:
0000-0001-8511-790X
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Condensed Matter Physics
Oxford college:
Corpus Christi College
Role:
Author
ORCID:
0000-0002-0301-8033


Publisher:
Springer Nature
Journal:
Nature Communications More from this journal
Volume:
12
Article number:
6955
Place of publication:
England
Publication date:
2021-11-29
Acceptance date:
2021-10-26
DOI:
EISSN:
2041-1723
Pmid:
34845219


Language:
English
Keywords:
Pubs id:
1214171
Local pid:
pubs:1214171
Deposit date:
2022-01-17

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