Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 45: Ultrafast Electron Dynamics at Surfaces and Interfaces IV
O 45.6: Vortrag
Mittwoch, 20. März 2024, 11:45–12:00, MA 041
Influence of defects on ultrafast charge separation in van der Waals heterostructures — •Johannes Gradl1, Niklas Hofmann1, Leonard Weigl1, Raül Perea-Causín2, Ermin Malic3, Daniel Hernangómez Pérez4, Sivan Refaely-Abramson4, and Isabella Gierz1 — 1University of Regensburg — 2Chalmers University of Technology — 3University of Marburg — 4Weizmann Institute of Science
Ultrafast charge separation is crucial for efficiently converting sunlight into electrical energy. This phenomenon commonly occurs in different van der Waals heterostructures [1] where the transfer rates for electrons and holes are determined by the band alignment and interlayer hybridization. Recently, it has been realized that defects might enhance the lifetime of the charge separated state significantly [2,3]. A detailed microscopic understanding of defect-assisted charge transfer, however, is lacking. We deliberately generate sulfur vacancies in a prototypical WS2-graphene heterostructure and probe their influence on the charge transfer dynamics with time- and angle-resolved photoemission spectroscopy. We interpret our results based on existing theory [4,5].
[1] Nat. Nanotechnol. 13, 994 (2018)
[2] Sci. Adv. 7, eabd9061 (2021)
[3] Phys. Rev. Lett. 127, 276401 (2021)
[4] Phys. Rev. B 107, 075419 (2023)
[5] Nano Lett. 23, 5995 (2023)
Keywords: time-resolved ARPES; van der Waals heterostructure; charge transfer