Regensburg 2010 – scientific programme

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DS: Fachverband Dünne Schichten

DS 29: Poster: Molecular Spintronics, Biomolecular and Functional Organic Layers, Organic Electronics and Photovoltaics, Plasmonics and Nanophotonics, Organic Thin Films, Nanoengineered Thin Films, Thin Film Characterisation,

DS 29.24: Poster

Wednesday, March 24, 2010, 15:00–17:30, Poster A

Investigation of degradation phenomena of blue fluorescent OLEDs — •Ruben Seifert, Sebastian Scholz, Björn Lüssem, and Karl Leo — Institut für Angewandte Photophysik TU Dresden, D-01062 Dresden

During the last years, the lifetime of organic light emitting diodes (OLEDs) based on small molecules has greatly improved. However, there are still problems concerning the long term stability of blue emitters. In this contribution, we describe experiments on p-i-n bottom emitting OLEDs with the blue emitting substance Spiro-DPVBi (2,2',7,7 tetrakis (2,2diphenylvinyl)-spiro-9,9'-biuoren). It is known that the main intrinsic degradation process of Spiro-DPVBi is not influenced by the electric current or the applied field, but it has been proposed that the degradation is caused by the exciton density [1]. To prove this, we did experiments on hole- and electron-only devices with very high charge carrier densities. To investigate the influence of excitons on degradation, we compare an electrical and an UV-aged OLED with the same initial luminance. Since Spiro-DPVBi is an efficient fluorescent material, the UV-radiation is creating singlet excitons only. However, both samples show similar degradation behavior, so that we can assume that the degradation of Spiro-DPVBi is mainly caused by singlet excitons.

[1] Winter, S., Reineke, S., Walzer, K., Leo, K., Proc. of SPIE Vol.6999, 69992N-8 (2008).