Regensburg 2007 – wissenschaftliches Programm

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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices

SYOE 8: Poster Session SYOE

SYOE 8.15: Poster

Dienstag, 27. März 2007, 18:00–20:00, Poster B

Investigation of interlayers at the organic-metal interface by laser desorption/ionization time-of-flight mass spectrometry — •Sebastian Scholz, Qiang Huang, Karsten Walzer, and Karl Leo — Institut für Angewandte Photophysik, Technische Universität Dresden, D-01062 Dresden

Since Tang and VanSlyke invented the first efficient OLED, much work was done to improve organic semiconductor device characteristics. Hereby, the behavior of the interfaces between the organics and the metals used as anode and cathode is still an open question. We investigate these metal/organic and organic/metal interfaces with laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF-MS) and discuss differences between them. The main advantages of this technique are the possibilities to analyze undestroyed molecules, to trace impurities, degradation products, and photo-chemical reaction products as well as metal-organic adducts on organic semiconductor thin films. We study commonly used metals like Ag and Al as bottom and top contacts and different hole and electron transport materials like MeO-TPD and BPhen. We find that organic materials evaporated onto previously deposited metals create a sharp interface without further reactions, while the evaporation of "hot" metal onto organic films may cause chemical reactions within the underlying organic material. This leads to improved electron injection into gap states of electron transport materials from the top metal contact, while for the injection of holes, a sharp interface without chemically modified interlayers is beneficial.