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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 39: Focus Session: Ultrafast Processes in Organic Semiconductors and Perovskites I (joint session O/CPP)
CPP 39.8: Talk
Thursday, March 21, 2024, 12:45–13:00, MA 004
Formation of charge-transfer excitons across the hybrid PTCDA/WSe2 interface — •Wiebke Bennecke1, David Schmitt1, Jan Philipp Bange1, Ignacio Gonzalez Oliva2, Anna Seiler1, Lukas Renn1, Mattis Langendorf1, Daniel Steil1, Sabine Steil1, R. Thomas Weitz1, Peter Puschnig3, Claudia Draxl2, Marcel Reutzel1, G. S. Matthijs Jansen1, and Stefan Mathias1 — 1I. Physikalisches Institut, Georg-August-Universität Göttingen — 2Institut für Physik, Humboldt-Universität zu Berlin — 3Institute of Physics, University of Graz
Heterostructures consisting of van-der-Waals materials and organic molecules are a promising material platform due to their potential to combine the flexibility of organic chemistry with the remarkable optoelectronic properties of 2D materials. Here, we use femtosecond photoemission momentum microscopy to study ultrafast exciton dynamics in monolayer PTCDA adsorbed on WSe2. By employing the concepts of photoemission orbital tomography, which has recently been shown to be capable of capturing key excitonic properties [1, 2], we are able to unambiguously identify the different excitonic states formed after optical excitation of WSe2. We find that a localized long-lived charge-transfer exciton is formed on a picosecond timescale, where the hole resides in the WSe2 and the electron is being transferred to the lowest unoccupied molecular orbital of PTCDA.
[1] C. Kern et al., Phys. Rev. B 108, 085132 (2023)
[2] W. Bennecke et al., arXiv preprint arXiv:2303.13904 (2023)
Keywords: Ultrafast momentum microscopy; Photoemission orbital tomography; Excitons