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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 3: Organic Electronics and Photovoltaics - Layer Morphology and Molecular Aggregation
CPP 3.10: Vortrag
Montag, 12. März 2018, 12:15–12:30, C 243
Control of molecular orientation on a single substrate by changing growth parameters leads to switching of thin-film optical properties — •Giuliano Duva1, Linus Pithan2, Alexander Gerlach1, Alexander Janik1, Alexander Hinderhofer1, and Frank Schreiber1 — 1Eberhardt Karls Universität Tübingen, Tübingen, Germany — 2European Synchrotron Research Facility (ESRF), Grenoble, France
The Optical response of many organic semiconductors (OSC) can exhibit anisotropy depending on the average orientation of the molecular components [1]. Diindenoperylene (DIP) is an OSC whose HOMO-LUMO transition dipole moment is parallel to the long molecular axis. Organic Molecular Beam Deposition (OMBD) allows a high degree of control over the thin film structure. Using OMBD, uniaxially ordered DIP films in a standing-up configuration at room temperature are obtained exhibiting a strong optical anisotropy, with the out-of-plane component of the dielectric function being roughly ten times higher than the in-plane component in the visible spectrum [2]. Here we present a method to change the molecular orientation without modifying the substrate or reducing crystal quality. Growth via OMBD followed by annealing allows to obtain ordered, atmosphere-stable films of mostly lying-down DIP exhibiting inverted optical properties compared to films of standing-up DIP. We also discuss a possible mechanism to explain this effect.
[1] A. Hinderhofer et al. Chem. Phys. Chem. 13 (2012).
[2] U. Heinemeyer et al. Phys. Rev. B 78 (2008).