Berlin 2018 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 3: Organic Electronics and Photovoltaics - Layer Morphology and Molecular Aggregation

CPP 3.10: Talk

Monday, March 12, 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).