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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 2: Organic Electronics and Photovoltaics (joint session with DS/HL/O) I
CPP 2.8: Talk
Monday, March 31, 2014, 11:45–12:00, ZEU 222
Temperature-dependent molecular orientation of the organic semiconductor PTCDI-C8: Optical and structural properties — •Sebastian Bommel1,2, Linus Pithan2, Christopher Weber2, Anton Zykov2, Gonzalo Santoro1, Stephan V. Roth1, Jörg Megow2, and Stefan Kowarik2 — 1Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, D-22607 Hamburg, Germany — 2Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, D-12489 Berlin, Germany
Optical and structural properties of molecular materials are not only essential for the rational design of opto-electrical devices, but also for the understanding of intermolecular interactions. Here, we report on the structural and optical properties of the organic semiconductor PTCDI-C8 investigated by temperature-dependent Grazing Incidence X-ray Diffraction (GIXD) and photoluminescence (PL) measurements. Our in situ studies yield a large impact of temperature on unit cell parameters and optical transitions. The energy of the optical transition E10-E01 in the PL spectra shifts from 1.80 eV for 273 K to 1.85 eV for 413 K. Furthermore, a rearrangement of the molecular ensemble was found, indicated by a large change of the beta-angle of the PTCDI-C8 unit cell from 107∘ (273 K) to 102∘ (413 K). The influence of these structural changes, which are an indication for a change of molecular orientation with temperature, on the optical properties will be discussed in detail. Additionally, the structural and optical properties are supported by temperature-dependent molecular dynamics (MD) simulation based calculations.