Femtosecond time-resolved two-photon photoemission studies of ultrafast carrier relaxation in Cu2O photoelectrodes

Mario Borgwardt, Stefan T. Omelchenko, Marco Favaro, Paul Plate, Christian Höhn, Daniel Abou-Ras, Klaus Schwarzburg, Roel van de Krol, Harry A. Atwater, Nathan S Lewis, Rainer Eichberger, Dennis Friedrich

Research output: Contribution to journalArticle

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Abstract

Cuprous oxide (Cu2O) is a promising material for solar-driven water splitting to produce hydrogen. However, the relatively small accessible photovoltage limits the development of efficient Cu2O based photocathodes. Here, femtosecond time-resolved two-photon photoemission spectroscopy has been used to probe the electronic structure and dynamics of photoexcited charge carriers at the Cu2O surface as well as the interface between Cu2O and a platinum (Pt) adlayer. By referencing ultrafast energy-resolved surface sensitive spectroscopy to bulk data we identify the full bulk to surface transport dynamics for excited electrons rapidly localized within an intrinsic deep continuous defect band ranging from the whole crystal volume to the surface. No evidence of bulk electrons reaching the surface at the conduction band level is found resulting into a substantial loss of their energy through ultrafast trapping. Our results uncover main factors limiting the energy conversion processes in Cu2O and provide guidance for future material development.

Original languageEnglish
Article number2106
JournalNature communications
Volume10
Issue number1
DOIs
Publication statusPublished - Dec 1 2019

Fingerprint

Photoemission
Photons
photoelectric emission
Electrons
Photoelectron Spectroscopy
photons
Platinum
Hydrogen
Spectrum Analysis
Photocathodes
water splitting
Water
photovoltages
energy conversion
photocathodes
Photoelectron spectroscopy
Conduction bands
Charge carriers
Energy conversion
Interfacial energy

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

Cite this

Borgwardt, M., Omelchenko, S. T., Favaro, M., Plate, P., Höhn, C., Abou-Ras, D., ... Friedrich, D. (2019). Femtosecond time-resolved two-photon photoemission studies of ultrafast carrier relaxation in Cu2O photoelectrodes. Nature communications, 10(1), [2106]. https://doi.org/10.1038/s41467-019-10143-x

Femtosecond time-resolved two-photon photoemission studies of ultrafast carrier relaxation in Cu2O photoelectrodes. / Borgwardt, Mario; Omelchenko, Stefan T.; Favaro, Marco; Plate, Paul; Höhn, Christian; Abou-Ras, Daniel; Schwarzburg, Klaus; van de Krol, Roel; Atwater, Harry A.; Lewis, Nathan S; Eichberger, Rainer; Friedrich, Dennis.

In: Nature communications, Vol. 10, No. 1, 2106, 01.12.2019.

Research output: Contribution to journalArticle

Borgwardt, M, Omelchenko, ST, Favaro, M, Plate, P, Höhn, C, Abou-Ras, D, Schwarzburg, K, van de Krol, R, Atwater, HA, Lewis, NS, Eichberger, R & Friedrich, D 2019, 'Femtosecond time-resolved two-photon photoemission studies of ultrafast carrier relaxation in Cu2O photoelectrodes', Nature communications, vol. 10, no. 1, 2106. https://doi.org/10.1038/s41467-019-10143-x
Borgwardt, Mario ; Omelchenko, Stefan T. ; Favaro, Marco ; Plate, Paul ; Höhn, Christian ; Abou-Ras, Daniel ; Schwarzburg, Klaus ; van de Krol, Roel ; Atwater, Harry A. ; Lewis, Nathan S ; Eichberger, Rainer ; Friedrich, Dennis. / Femtosecond time-resolved two-photon photoemission studies of ultrafast carrier relaxation in Cu2O photoelectrodes. In: Nature communications. 2019 ; Vol. 10, No. 1.
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