SKM 2023 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 19: Organic Electronics and Photovoltaics I (joint session CPP/HL)
HL 19.3: Talk
Tuesday, March 28, 2023, 10:00–10:15, GÖR 226
Optical properties of perfluorotetracene (PFT) crystal polymorphs — •Ana Maria Valencia1,2 and Caterina Cocchi1,2 — 1Institut für Physik, Carl von Ossietzky Universität Oldenburg — 2Physics Dept., Humboldt-Universität zu Berlin und IRIS Adlershof
The family of perfluorinated acenes is gaining popularity among organic materials for optoelectronics. Since the electronic and optical properties of molecular solids are crucially dependent on their packing motifs, it is crucial to consider crystalline phases in the simulations to understand the structure-property relationships of these materials, especially regarding electronic correlations and excitations. Here, we investigate from first principles by means of density functional theory and many-body perturbation theory the electronic structure and the optical excitations of two crystal polymorphs of perfluorotetracene, considering for comparison tetracene and the corresponding isolated molecules. This way, we can assess the effects of fluorination as well as of the crystal periodicity. We find that the absorption spectra are only mildly influenced by the packing motif. However, our analysis gives insight into the exciton binding energies as well as the spatial distribution of the excitons. We inspect not only the first excitations but also the higher-energy ones, thus providing an all-around understanding of the optical excitations in these materials.