Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 38: Organic-Inorganic Hybrid Systems and Organic Films V
O 38.6: Vortrag
Dienstag, 21. März 2017, 15:30–15:45, WIL A317
Electronic and optical excitations at the pyridine@ZnO hybrid interface — •Olga Turkina, Dmitrii Nabok, Andris Gulans, Caterina Cocchi, and Claudia Draxl — Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Germany
Insight from ab initio theory is essential in order to gain an understanding of opto-electronic properties of organic-inorganic hybrid materials, such as the correct level alignment and the creation of hybrid excitons. We investigate a prototypical system composed of a pyridine molecule that is chemisorbed on a non-polar ZnO(10-10) surface. We employ all-electron density-functional theory in combination with many-body perturbation theory (G0W0/BSE). The G0W0 approximation describing one-particle excitations is used to determine the electronic structure, while the Bethe-Salpeter equation describing two-particle excitations is solved to obtain the absorption spectrum. We reveal the nature of the optical excitations at the interface by analysing the character of the involved transitions and visualizing the exciton wave-function. Thus, we find evidence of excitons exhibiting different character across different spectral regions. The onset of the spectrum is dominated by bright and strongly bound hybrid and ZnO character excitons. In particular, the first strongly bound and most intense exciton at 1.8 eV is of hybrid nature. In the visible region, we find predominantly low intensity hybrid excitons, whereas in the UV region, we find dark excitons exhibiting charge-transfer character, with the corresponding electron and the hole delocalized on either ZnO or pyridine.