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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