Berlin 2012 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 25: Organic electronics and photovoltaics: electronic properties II (jointly with CPP, HL, O)
DS 25.5: Vortrag
Mittwoch, 28. März 2012, 12:30–12:45, H 2032
Octithiophene on Au(111): Coverage dependent adsorption geometry and exciton dynamics — •Lea Bogner1, Erwan Varene1, Yan Pennec2, and Petra Tegeder1 — 1Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany — 2University of British Columbia, department of Chemistry and Physics, Vancouver, B.C. V6T 1Z4, Canada
Semiconducting organic molecules exhibit promising properties for applications in optoelectronic devices such as organic photovoltaic cells or organic light emitting diodes. In order to fully understand and improve the functionalities of organic semiconductors the investigation of adsorption properties, electronic structure and charge carrier dynamics at their interfaces with inorganic substrates plays a crucial role.
Octithiophene (8T) is the longest unsubstituted oligothiophene synthesized up to now and possesses the highest carrier mobility. Whereas several surface science studies on sexithiophene interfaces may be found in literature, little is known so far about 8T.
The adsorption geometry, electronic structure and exciton dynamics as function of 8T coverage have been investigated by means of scanning tunnelling microscopy (STM), high-resolution electron energy loss spectroscopy (HREELS) and time-resolved two-photon photoemission (2PPE). We found that 8T undergoes a change in the adsorption geometry from flat-lying in the sub-monolayer regime to a tilted configuration for the mono- and bilayer coverage. The photoemission intensities of the HOMO and HOMO-1 features as well as the exciton decay dynamics exhibit a strongly coverage dependent behavior.