Regensburg 2007 – scientific programme

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DS: Fachverband Dünne Schichten

DS 17: Contact Properties (SYOE 10)

DS 17.2: Talk

Wednesday, March 28, 2007, 17:30–17:45, H32

Comparison of the charge injection barrier at realistic and ideal metal/organic interfaces: metals become faceless — •Mandy Grobosch and Martin Knupfer — Leibniz-Institut für Festkörper- und Werkstoffforschung, Dresden, Germany

Most of the organic electronic devices are nowadays fabricated under poor vacuum conditions. In this regard, there is only little knowledge about the impact of contamination of the metal electrode on the charge injection barrier in this kind of electronic devices. In our study we have performed X-ray and ultra violet photoemission spectroscopy (XPS, UPS) on interfaces between the organic semiconductor α-sexithiophene and sputter cleaned (ideal) metals as well as contaminated (realistic) metals. As metal substrates we have used silver, gold, palladium, and platinum. These metals provide us a wide range of metal work functions from 4.2 eV for silver up to 5.5 eV for platinum. For all interfaces of α-sexithiophene and contaminated metals we have observed a reduction of the interface dipole and the hole injection barrier. The charge injection barrier in all four cases is almost independent of the underlying metal (within an error of 0.2 eV) and the interface dipole remains a finite size. We could demonstrate that the injection barrier of realistic interfaces is very different from that of the respective clean interfaces. Moreover, a loss of the individual characteristic of the metal upon contamination is observed - it becomes faceless.