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O: Fachverband Oberflächenphysik
O 47: Poster Electron-driven Processes
O 47.5: Poster
Dienstag, 18. März 2025, 18:00–20:00, P2
Triplet exciton dynamics at the tetracene/a-Si/c-Si(111) interface — •Marvin Krenz1,2, Simone Sanna1, Wolf Gero Schmidt2, and Uwe Gerstmann2 — 1Institut für Theoretische Physik, Justus-Liebig Universität Gießen, 35392 Gießen, Germany — 2Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
Exciton transfer is highly relevant for many physical, chemical, and biological processes. The transfer of triplet excitons across the tetracene-silicon interface in sensitized solar cells is a recent example in this context [1]: The excitons, generated by singlet fission in tetracene (Tc), promise to increase the cell efficiency from the single-junction limit of 29% to values as high as 35% [2]. In a previous work, we showed the significance of dangling bond (db) defects for the triplet transfer [3] at a model interface, where tetracene was bonded to an ideal c-Si(111) surface. Here, we present ab initio calculations for a more realistic structure, with a thin film of amorphous silicon (a-Si:H) in-between, resulting in a Tc/a-Si/c-Si model structure. We find that dbs are vital for the exciton transfer also in this case. Dbs at the a-Si/c-Si interface or in the a-Si interlayer itself affect the exciton transfer differently. Generally, it is found that the a-Si layer is energetically favourable for excitation transfer. However, the exciton electron tends to be trapped in a-Si conduction band tail states. Thus, the exciton transfer requires an external field to be completed. [1] M. Einzinger et al. Nature 571, 90*94 (2019). [2] A. Rao et al., Nat. Rev. Mater. 2, 17063 (2017). [3] M. Krenz et al., Phys. Rev. Lett. 132, 076201 (2024)
Keywords: Exciton transfer; a-Si/c-Si interface; DFT; Defects; dangling bond