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O: Fachverband Oberflächenphysik
O 78: Focus Session: Ultrafast Processes in Organic Semiconductors and Perovskites I (joint session O/CPP)
O 78.2: Talk
Thursday, March 21, 2024, 11:00–11:15, MA 004
Fluctuations and exciton dynamics in molecular semiconductors — •Alexander Neef1, Samuel Beaulieu2, Sebastian Hammer3, Shuo Dong4, Tommaso Pincelli1,5, Julian Maklar1, R.Patrick Xian6, Anke Krueger7, Martin Wolf1, Laurenz Rettig1, Jens Pflaum8 und Ralph Ernstorfer1,5 — 1Fritz-Haber-Institut — 2Centre Lasers Intenses et Applications (CELIA) — 3McGill University — 4Chinese Academy of Sciences — 5Technical University Berlin — 6University of Toronto — 7University of Stuttgart — 8University of Wuerzburg
Time- and angle-resolved photoemission spectroscopy (trARPES) is a cutting-edge technique to study the electronic structure of materials out-of-equilibrium. Advances in instrumentation now allow taking multidimensional photoemission data sets of delocalized electrons in conventional semiconductors and the reconstruction of spatially confined molecular orbitals. I will present our recent results on trARPES studies of the fluctuation-dominated electronic structure of molecular semiconductors. Furthermore, I will talk about how trARPES made it possible to decipher a complex multiexcitonic process: singlet exciton fission [1]. Apart from the answers gained, a pressing question emerged: how can singlet exciton fission go uphill in energy in certain systems? Our work highlights the need for theories that are able to capture the behavior of excited states in a fluctuating landscape.
[1] Neef et al., Nature 616 (2023) https://www.nature.com/articles/s41586-023-05814-1
Keywords: Singlet exciton fission; trARPES; Transient localization theory; Molecular semiconductors