Sonderforschungsbereich 595

Fatigue of organic electronic devices

Dr. A. Gassmann (Div. Electronic Material Properties)
Prof. Dr. H. v. Seggern (Div. Electronic Material Properties)

The project D4 deals with the aspect of fatigue in organic devices constituting components in modern organic electronics. The success of organic electronic products such as organic displays or organic circuitry is strongly related to its stability and hence to the stability of its individual components, namely organic light emitting diodes and field-effect transistors. Hence, knowledge about mechanisms leading to fatigue of organic devices is essential to further organic electronics.

In project D4 the fatigue of organic devices is exemplarily investigated by means of organic light emitting diodes (OLEDs). The goal is to pinpoint the mechanisms leading to the drop of performance during OLED operation, to work out and evaluate possible stabilizing counteractions and finally to improve the lifetime of OLEDs.

In order to elucidate the fatigue of OLEDs, the fundamental stresses causing the device degradation have to be unveiled. These damaging stresses have to be found among strong electric fields, high density of charge carriers or high density of excitation. The stresses alter specific system properties which must be located and it has to be clarified how these altered properties influence the device function. Thus, the changes of the injection, the transport and the recombination of charge carriers, as well as of excitonic processes have to be investigated during the device operation.

The mentioned investigations are strongly related to other projects of the SFB 595. The improvement and stabilization of the charge carrier injection at the employed contacts is performed in a close collaboration with project D3 (Klein), while chemical reasons for the fatigue will be clarified together with project A5 (Rehahn). In combination with theoretical considerations from project C5 (Genenko) and C2 (Albe) relating the overall device performance to local system properties a detailed understanding of the fatigue in OLEDs can be gained, giving rise to new concepts of device stabilization.