Eric Langer oral presentation (PB3-Thu1-2-1)
Depth profiling of organic multilayer structures in OLEDs
1 CEA, LETI, MINATEC Campus, 17 rue des Martyrs, 38054 Grenoble, France
2 Physics of Matter and Radiation, University of Namur, rue Joseph Grafé 2, 5000 Namur, Belgium
Organic electronic devices have already found their way into our everyday life in form of organic photovoltaic devices and mainly organic light emitting diode (OLED) displays. Alongside their numerous advantages like high efficiency, transparency or flexibility, there are still some drawbacks. Mainly the shortened lifetime because of degradation of the organic components causes problems. Chemical depth profiling techniques like time-of-flight secondary ion mass spectrometry (ToF-SIMS) can help to identify the source of degradation to improve the device lifetime. Modern OLED devices consist of several ultrathin organic layers surrounded by inorganic electrodes. The layer thicknesses ranging from 1 nm to several 10 nm present a big challenge for depth profiling techniques.
Here, we show the characterization of the organic multilayer stack in green OLEDs by ToF-SIMS measurements using Argon cluster sputtering. We use a scotch-tape process to remove the inorganic encapsulation and the top electrode. Argon cluster sputtering then allows for characterization of the organic layers with high depth resolution. Additionally, x-ray photoelectron spectroscopy (XPS) measurements are performed to optimize sputter parameters and to ensure minimal sputter induced damage during analysis. Using this approach, it is possible to gain precise chemical information of the organic multilayer stack in OLEDs and even to characterize aged samples and to identify sources of device degradation.