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Strong absorption and ultrafast localisation in NaBiS2 nanocrystals with slow charge-carrier recombination

Abstract:

I-V-VI2 ternary chalcogenides are gaining attention as earth-abundant, nontoxic, and air-stable absorbers for photovoltaic applications. However, the semiconductors explored thus far have slowly-rising absorption onsets, and their charge-carrier transport is not well understood yet. Herein, we investigate cation-disordered NaBiS2 nanocrystals, which have a steep absorption onset, with absorption coefficients reaching >105 cm−1 just above its pseudo-direct bandgap of 1.4 eV. Surprisingly, we also observe an ultrafast (picosecond-time scale) photoconductivity decay and long-lived charge-carrier population persisting for over one microsecond in NaBiS2 nanocrystals. These unusual features arise because of the localised, non-bonding S p character of the upper valence band, which leads to a high density of electronic states at the band edges, ultrafast localisation of spatially-separated electrons and holes, as well as the slow decay of trapped holes. This work reveals the critical role of cation disorder in these systems on both absorption characteristics and charge-carrier kinetics.

Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1038/s41467-022-32669-3

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Role:
Author
ORCID:
0000-0002-4576-2338
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Role:
Author
ORCID:
0000-0003-4577-9647
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Author
ORCID:
0000-0001-5507-1445
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Author
ORCID:
0000-0002-1429-0219


Publisher:
Springer Nature
Journal:
Nature Communications More from this journal
Volume:
13
Article number:
4960
Publication date:
2022-08-24
Acceptance date:
2022-08-09
DOI:
EISSN:
2041-1723
Pmid:
36002464


Language:
English
Keywords:
Pubs id:
1275715
Local pid:
pubs:1275715
Deposit date:
2022-11-23

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