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Limitation of Fermi level shifts by polaron defect states in hematite photoelectrodes

Lohaus, Christian ; Klein, Andreas ; Jaegermann, Wolfram (2021)
Limitation of Fermi level shifts by polaron defect states in hematite photoelectrodes.
In: Nature Communications, 9 (1)
doi: 10.26083/tuprints-00019797
Article, Secondary publication, Publisher's Version

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Item Type: Article
Type of entry: Secondary publication
Title: Limitation of Fermi level shifts by polaron defect states in hematite photoelectrodes
Language: English
Date: 2021
Place of Publication: Darmstadt
Publisher: Springer Nature
Journal or Publication Title: Nature Communications
Volume of the journal: 9
Issue Number: 1
Collation: 7 Seiten
DOI: 10.26083/tuprints-00019797
Corresponding Links:
Origin: Secondary publication service
Abstract:

The optical band gap is a major selection criterion for an absorber in photocatalytic water splitting. Due to its ideal value hematite has been intensively investigated without reaching the expectation, yet. In this work, the Fermi level positions in hematite due to doping and contact formation are investigated. An upper boundary for the Fermi level position at 1.8 eV above the valence band maximum due to the formation of polarons is identified. This results in a different concept of the effective band gap for hematite which we believe is transferable to any material with competing polaron formation after optical excitation: the optical band gap of 2.2 eV deviates from an effective electronic band gap of 1.75 eV. The polaron state acts as a limit in (quasi-)Fermi level shift, restricting the potential of charge transfer reactions. Additionally, it has led to an incorrect determination of the band edge positions of hematite in electrochemical contacts.

Status: Publisher's Version
URN: urn:nbn:de:tuda-tuprints-197979
Classification DDC: 600 Technology, medicine, applied sciences > 620 Engineering and machine engineering
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Surface Science
Date Deposited: 29 Oct 2021 12:25
Last Modified: 14 Aug 2023 09:50
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/19797
PPN: 495611603
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