Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 55: Inorganic/Organic Interfaces: Electronic Properties II

O 55.2: Vortrag

Mittwoch, 18. März 2015, 15:30–15:45, HE 101

Site-specific transport levels in a crystalline organic thin film — •Tomoki Sueyoshi, Martin Willenbockel, Serguei Soubatch, and Stefan Tautz — Peter Grünberg Institut (PGI-3), JARA, Forschungszentrum Jülich, Germany

Recent studies have revealed that the electronic properties of organic semiconductor thin films are not only determined by the nature of individual constituent molecules, but also correlated with geometric structure in which the molecules arrange. If a crystalline organic thin film consisting of single-component molecules contains several different molecular species in its unit cell, molecular orbital energies of such species could be different from species to species depending on their relative geometry and orientation. Since it is the highest occupied/lowest unoccupied molecular orbitals (HOMO/LUMO) which are involved in charge transport, the energy dispersity of these transport levels may dominate the transport properties of organic semiconductors.

A previous scanning tunneling spectroscopy study revealed that a LUMO energy dispersity up to 0.5 eV originates from the intermolecular polarization/interaction on the LUMO of six different tetracene species in the complex bilayer β-phase on Ag(111). To access the one on the HOMO, we have performed photoelectron spectroscopy of the tetracene β-phase and observed a similar energy dispersity of the HOMO. In this talk, we will discuss the assignment of the observed HOMO components and provide a comprehensive picture of the transport levels of the tetracene β-phase.