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

Huang, Yi-Teng; Kavanagh, Seán R; Righetto, Marcello; Rusu, Marin; Levine, Igal; Unold, Thomas; Zelewski, Szymon J; ... Hoye, Robert LZ; + view all (2022) Strong absorption and ultrafast localisation in NaBiS2 nanocrystals with slow charge-carrier recombination. Nature Communications , 13 , Article 4960. 10.1038/s41467-022-32669-3. Green open access

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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.

Type: Article
Title: Strong absorption and ultrafast localisation in NaBiS2 nanocrystals with slow charge-carrier recombination
Location: England
Open access status: An open access version is available from UCL Discovery
DOI: 10.1038/s41467-022-32669-3
Publisher version: https://doi.org/10.1038/s41467-022-32669-3
Language: English
Additional information: © The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/ licenses/by/4.0/.
UCL classification: UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL
URI: https://discovery.ucl.ac.uk/id/eprint/10154785
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