| DEFECT ANALYSIS IN ORGANIC SEMICONDUCTOR DEVICES |
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TYPICAL DEFECTS THAT CAN BE OBSERVED IN ORGANIC SEMICONDUCTOR DEVICES ARE:
- Black spots
- Particles
- Coating Inhomogeneities
- Cathode defects
- Difference in wetting properties
FOR STUDYING THESE DEFECTS DIFFERENT METHODS ARE COMMONLY USED. THESE INCLUDE:
- Optical inspection with a microscope
- Spatially resolved inspection of emission in OLEDs
- Electrical characterization
- AFM
- Scanning electron microscopy
HOWEVER, ALL THESE METHODS HAVE SEVERAL DRAWBACKS. VERY OFTEN THEY ARE:
- Only suited for light emitting devices
- Not suited for testing the final devices (incl. encapsulation)
- Only suited for general device characteristics, i. e. no spatially resolved information
- Destructive testing methods
The fact that manufacturing processes are the same for the different kinds of applications of organic semiconductors (OLED, OPV, etc.), the limitation that the above mentioned methods can very often only be used for light emitting devices constitutes a severe drawback. Another drawback of all these methods is that they can only be used for visualizing defects. First steps in defect analysis, e.g. discrimination between interface and bulk effects, are not possible with any of these commonly used methods. |
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