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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
Artikel, Zweitveröffentlichung, Verlagsversion

Kurzbeschreibung (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.

Typ des Eintrags: Artikel
Erschienen: 2021
Autor(en): Lohaus, Christian ; Klein, Andreas ; Jaegermann, Wolfram
Art des Eintrags: Zweitveröffentlichung
Titel: Limitation of Fermi level shifts by polaron defect states in hematite photoelectrodes
Sprache: Englisch
Publikationsjahr: 2021
Verlag: Springer Nature
Titel der Zeitschrift, Zeitung oder Schriftenreihe: Nature Communications
Jahrgang/Volume einer Zeitschrift: 9
(Heft-)Nummer: 1
Kollation: 7 Seiten
DOI: 10.26083/tuprints-00019797
URL / URN: https://tuprints.ulb.tu-darmstadt.de/19797
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Herkunft: Zweitveröffentlichungsservice
Kurzbeschreibung (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: Verlagsversion
URN: urn:nbn:de:tuda-tuprints-197979
Sachgruppe der Dewey Dezimalklassifikatin (DDC): 600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften und Maschinenbau
Fachbereich(e)/-gebiet(e): 11 Fachbereich Material- und Geowissenschaften
11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft
11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Oberflächenforschung
Hinterlegungsdatum: 29 Okt 2021 12:25
Letzte Änderung: 01 Nov 2021 07:16
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