Berlin 2024 – wissenschaftliches Programm

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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 39.2: Vortrag

Donnerstag, 21. März 2024, 11:00–11:15, MA 004

Fluctuations and exciton dynamics in molecular semiconductors — •Alexander Neef¹, Samuel Beaulieu², Sebastian Hammer³, Shuo Dong⁴, Tommaso Pincelli^1,5, Julian Maklar¹, R.Patrick Xian⁶, Anke Krueger⁷, Martin Wolf¹, Laurenz Rettig¹, Jens Pflaum⁸ und Ralph Ernstorfer^1,5 — 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