Analysis of Organic Layers
Organic layers are layers of molecules that are deliberately applied to surfaces. The purpose of the layers is to protect the coated surface, to refine it or to provide it with completely new physical or chemical properties. The thickness of the used organic layers varies greatly and depends largely on their intended use and the type of deposition. For example, self-assembled organic monolayers (SAMs) are used as a transparent anti-reflective layer on optics, as a self-cleaning lotus layer on glasses or as a tarnish or corrosion protection layer on precious metals. Protection from corrosion or the achievement of special tribological properties is often a priority when using thicker organic layers based on mineral oils (e.g. lubricants) or high-quality polymeric compounds (e.g. paint).
In addition to individual organic layers, more complex organic multi-layer systems have long been used in industry. Typical examples are automotive coatings or film laminates, which allow a combination of protective aspects (e.g. UV protection) and aesthetic purposes. Organic multi-layer systems as functional layers have led to a breakthrough in display technology in recent years. Displays based on organic light emitting diodes (OLEDs) now meet the highest demands on the brilliance of a screen and are usually more economic to manufacture than classic inorganic LEDs.
With regard to the analysis of organic (multi) layer systems, there are special requirements, since the determination of sequence, layer thicknesses and molecular composition of a layer system prohibits damage to molecular structures by the analysis. Many classic methods for determining layer structures in the field of semiconductor analysis (e.g. RBS, SEM, dynamic SIMS, ...) must fit here. The introduction of Ar cluster sources made it possible to sputter organic layers while keeping molecular structures intact. This enabled the rise of ToF-SIMS depth profiling as a technique to characterize thin organic layer structures. Now, ToF-SIMS could analyze organic layers and their interfaces in the same way it has been used to analyze inorganic layer structures. The following example illustrates the possibilities of organic depth profiling on an OLED layer system that was examined in the Tascon laboratory:
Organic depth profiling
Analysis of organic multilayer systems
For future developments of OLED based lighting systems, analytical support is needed when clarifying, among others, the following questions:
- Structure clarification 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 service life)
The above example from our laboratory shows the possibilities of analyzing organic layers (depth profiling) using the example of an OLED test structure. In this analysis, all listed substances were detected based on their molecular ions (e.g. NPD: C44H33N2+ ). In this way, the use of cluster projectiles for depth profiling offers the possibility to characterize molecular layer sequences in detail.
Further applications of this analysis methodology can be found, for example, in the characterization of thin polymer laminates or in in-situ cleaning of organically contaminated surfaces (e.g. paints). These types of analyses have been part of the daily work in the Tascon laboratory for many years.
Tascon - your partner for the analysis of organic layers
Do you work in your company with the analysis of organic layers and do you need the support of our laboratory? Then contact us and benefit from our many years of experience in the analysis of organic layers. We would be happy to advise you personally and without obligation in a free conversation. Our friendly and competent team looks forward to your inquiry.