Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 36: Poster Ib

HL 36.10: Poster

Dienstag, 8. März 2016, 15:00–19:00, Poster A

Polarization-resolved reflectance spectroscopy of crystalline perfluoropentacene on various substrates — •Robin Carl Döring, David Leimbach, Tobias Breuer, Gregor Witte, and Sangam Chatterjee — Faculty of Physics and Materials Science Center, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg, Germany

Perfluoropentacene (PFP) is the perfluorinated counterpart and hence n-type organic semiconductor to the prototypical p-type pentacene. It can be grown as highly crystalline thin films on various optically transparent substrates such as NaF, KCl, graphene and also graphene*s opaque multilayer counterpart, highly ordered pyrolytic graphite (HOPG). While PFP forms the typical herringbone motif on both NaF and KCl, it shows a π-stacking polymorph (PSP) on graphene and HOPG. Structural analyses show a π-stacking distance of only 3.07 Å, promising far higher values for electron and hole mobility and therefore greatly improved vertical transport, a desirable feature in potential organic electronic applications. Here, we investigate the influence of the packing motif and hence of the intermolecular coupling on the optoelectronic properties. Making use of polarization-resolved reflection contrast spectroscopy with high spatial resolution, we identify the corresponding exciton transition energies and correlate them with the orientation of crystalline domains and the substrate. Unfortunately, due to the face-on growth of the molecules, the π-stacking axis is inaccessible under normal angle of incidence. Hence, we perform close to grazing incidence photomodulated reflection spectroscopy.