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HL: Fachverband Halbleiterphysik
HL 16: Organic Semiconductors
HL 16.3: Vortrag
Dienstag, 18. März 2025, 10:00–10:15, H14
Excitons in organic donor-acceptor cocrystals — •Sebastian Anhäuser1, Ana Maria Valencia2, Caterina Cocchi2, and Gregor Witte1 — 1Philipps-Universität Marburg, FB Physik — 2Carl von Ossietzky Universität Oldenburg, Institut für Physik
Organic donor-acceptor heterostructures have gained significant attention due to their unique properties, such as low-bandgap semiconductivity and ambipolar transport, making them promising candidates for optoelectronic applications like organic photovoltaics. There, the formation of charge-transfer excitons is typically regarded as the precursor state for charge separation. However, the microscopic nature of these excitons is not yet well understood. In the presented study, we perform detailed polarization-resolved optical spectroscopy on high quality acene-perfluoroacene donor-acceptor single crystals in the optical and UV range. This approach allows us to investigate both the excitation energies and the transition dipole moments of various (charge-transfer-)excitons. Using complementary state-of-the-art first principles calculations based on density functional and many-body pertubation theory, we analyse the nature of different classes of excitons within the cocrystalline structure. Our findings provide a refined understanding of charge-transfer excitons in organic materials, paving the way for improved design strategies in organic optoelectronics.
Keywords: Excitons; Charge Transfer; Organic Semiconductors; Optical Spectroscopy; Density Functional Theory