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Photoexcited charge carrier dynamics in Sb2Se3(100)


Grad, Lisa; von Rohr, Fabian O; Zhao, Jianzhou; Hengsberger, Matthias; Osterwalder, Jürg (2020). Photoexcited charge carrier dynamics in Sb2Se3(100). Physical Review Materials, 4(10):105404.

Abstract

Antimony selenide (Sb2Se3) consists of one-dimensional ribbons that are van der Waals bonded to each other. Due to its favorable optoelectronic properties, it is a promising material for solar energy conversion. Owing to its narrow direct band gap and its high absorption coefficient it is an efficient absorber for solar light. Besides, it is cheap, stable in harsh environments, and abundant with low toxicity. For its use in solar devices, efficient transport of photoexcited charge carriers towards the active interface and long lifetimes at sufficiently high energies are mandatory. Here time-resolved two-photon photoemission experiments on the (100) surface of Sb2Se3 are presented. Data were taken along and perpendicular to the direction of the one-dimensional ribbons in order to unravel the anisotropic lifetimes and relaxation dynamics of photoexcited charge carriers. In both cases, various conduction bands could be populated and within the first picosecond ultrafast scattering towards the lowest conduction band was observed. Moreover, long lifetimes of up to 35 ps in the conduction band bottom at the surface were obtained and no sign of trapping in defect states was found. These measurements shed light on the relaxation and scattering of free carriers in Sb2Se3, which is the key for the design of Sb2Se3-based electrodes.

Abstract

Antimony selenide (Sb2Se3) consists of one-dimensional ribbons that are van der Waals bonded to each other. Due to its favorable optoelectronic properties, it is a promising material for solar energy conversion. Owing to its narrow direct band gap and its high absorption coefficient it is an efficient absorber for solar light. Besides, it is cheap, stable in harsh environments, and abundant with low toxicity. For its use in solar devices, efficient transport of photoexcited charge carriers towards the active interface and long lifetimes at sufficiently high energies are mandatory. Here time-resolved two-photon photoemission experiments on the (100) surface of Sb2Se3 are presented. Data were taken along and perpendicular to the direction of the one-dimensional ribbons in order to unravel the anisotropic lifetimes and relaxation dynamics of photoexcited charge carriers. In both cases, various conduction bands could be populated and within the first picosecond ultrafast scattering towards the lowest conduction band was observed. Moreover, long lifetimes of up to 35 ps in the conduction band bottom at the surface were obtained and no sign of trapping in defect states was found. These measurements shed light on the relaxation and scattering of free carriers in Sb2Se3, which is the key for the design of Sb2Se3-based electrodes.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
07 Faculty of Science > Physics Institute
Dewey Decimal Classification:530 Physics
Scopus Subject Areas:Physical Sciences > General Materials Science
Physical Sciences > Physics and Astronomy (miscellaneous)
Language:English
Date:26 October 2020
Deposited On:16 Dec 2020 13:52
Last Modified:17 Dec 2020 21:01
Publisher:American Physical Society
ISSN:2475-9953
OA Status:Green
Publisher DOI:https://doi.org/10.1103/PhysRevMaterials.4.105404

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