Regensburg 2010 – scientific programme

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DS: Fachverband Dünne Schichten

DS 15: [HL] Organic Semiconductors: Transistors and OLEDs (Joint Session DS/CPP/HL/O)

DS 15.11: Talk

Tuesday, March 23, 2010, 12:15–12:30, H15

Energy band alignment at the oxide-organic interface ITO/ZnPC determined by photoelectron spectroscopy — •Jürgen Gassmann and Andreas Klein — Surface Science Department, Istitute of Materials Science, TU Darmstadt, Germany

The possibility to generate light on the front- and backside of an organic light-emitting diode (OLED) is given for inverted top-emitting OLEDs. For them the transparency of the back contact is crucial. Here transparent conductive oxides (TCO) like indium tin oxide (ITO) or zinc oxide are of special interest, because these films can be deposited with magnetron sputtering at room temperature. In this work the energy band alignment between the organic material zinc phthanalocyanine (ZnPC) and the transparent oxide ITO is evaluated. For this the X-ray photoelectron spectroscopy technique (XPS) is used and combined with an in-situ preparation of the films. The energy band alignments of the deposition sequences ITO on ZnPC and vice versa are compared. Here valence band offsets up to 1.3eV can be detected. The energy band alignment shows a strong dependence on the deposition sequence. Additionally the electrical and optical properties of ITO films sputtered at room temperature are investigated.