Organic Light Emitting Diodes (OLEDs)
Carbon based light sources
Organic light-emitting diodes (OLEDs) are regarded as pioneering approaches for producing large, diffuse light sources. OLEDs consist of a sequence of organic, semiconducting layers and are already being used in smaller displays and televisions. Because of its many advantages (e.g., very high contrast), an increasing popularity of this optical technology is expected.
Organic depth profiling
Depth profiling of organic multilayers
Analytical supports is necessary for the future development of OLED based lighting systems to clarify, among others, the following questions:
- structure elucidation in research and development
- Patent issues (identification of the organic molecules used)
- Influence of operating parameters (operating time, effect of temperature, humidity and oxygen, ...)
- failure analysis (e.g., shortened lifetime)
Until a few years ago, ToF-SIMS depth profiling was only available to determine layer structures for inorganic components. It was not until the introduction of sample erosion with large cluster ions (for example Ar1000+) that organic layer profiling, also referred to as organic depth profiling, became possible based on the profiling of characteristic molecules. The above example shows the possibilities of organic depth profiling using the example of an OLED test structure. In this analysis, all listed substances were detected by their molecular ions (e.g., NPD: C44H33N2+ ). Thus, the use of cluster projectiles for depth profiling offers the opportunity to characterize molecular layer sequences in detail.
Further applications of this analysis method can be found, for example, in the characterization of thin polymer laminates or the in-situ cleaning of surfaces with organic contamination (for example lacquers).