Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 99: Organic Semiconductors: Transport

HL 99.10: Vortrag

Freitag, 30. März 2012, 12:00–12:15, EW 203

Characterization of Codeposited Pentacene:Perfluoropentacene Thin-Films via Transmission Electron Microscopy — •Benedikt Haas, Katharina I. Gries, Tobias Breuer, Gregor Witte, and Kerstin Volz — Philipps-University Marburg, Faculty of Physics and Materials Science Center, 35032 Marburg, Germany

Organic semiconductors (OSC) are up-and-coming in research and industry. Perfluoropentacene (PFP) is the perfluorinated sibling of the well-known OSC pentacene (PEN), which exhibits high hole mobilities of up to 40 cm²/(Vs). The two materials are interesting in combination due to the fact that they have a very similar crystal structure but are p-type (PEN) and n-type (PFP) OSCs.

Samples of coevaporated PEN:PFP (grown by organic molecular beam deposition) on alkali halide substrates (KCl, NaF) were investigated using transmission electron microscopy (TEM). Beam damage is very critical for these materials but adequate sample preparation and microscope operation enables one to obtain invaluable information about the morphology and crystalline orientation.

TEM allows for a high spatial resolution of the occurring phase separation, including a 1:1 PEN:PFP mixed phase. The formation of different phases of the segregated PEN has also been evidenced, depending on the substrate used. First results concerning lattice spacings of the PEN:PFP mixed phase have been obtained and are of special interest because x-ray reflectivity analysis has been shown to be hindered due to the intricate phase separation.