Regensburg 2007 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 16: Organic Light Emitting Diodes (SYOE 9)
DS 16.3: Vortrag
Mittwoch, 28. März 2007, 15:00–15:15, H32
Photophysical properties of deep blue emitting Iridium complexes — •S. Haneder1, E. Da Como1, A. Rogach1, J. Feldmann1, P. Erk2, E. Fuchs2, K. Kahle2, O. Molt2, S. Nord2, H. Reichelt2, and G. Wagenblast2 — 1Photonics and Optoelectronics Group, LMU, 80799 München — 2BASF AG, 67056 Ludwigshafen
Improving the efficiency of lighting is imperative in optimizing the use of available energy resources. Electrophosphorescence based organic light-emitting diodes (OLEDs) have shown an internal efficiency of nearly 100% [1]. For lighting applications it is mandatory to produce OLEDs with white light emission, based on red, green and blue phosphors. Highly efficient green and red OLEDs have been successfully demonstrated. However, the development of blue emitting phosphors with reasonable photophysical stability and operational lifetime is a real challenge and still needs to be addressed.
Here we present results on a new family of phosphorescent Iridium carbene complexes [2] emitting in the blue. By a combination of steady-state and time-resolved spectroscopy techniques we study the photophysics of these complexes in thin films. The results demonstrate the influence of the ligand chemical structure in tuning the emission colour. Moreover, the nature of the non-radiative pathways involved in the emission process is figured out on the basis of phosphorescence lifetime and quantum yield measurements. These non-radiative pathways are important in limiting the overall device efficiency.
[1] Y. Sun et al., Nature 440, 908 (2006) [2] BASF AG, PCT Patent Appl. WO 2005/019373, August 19, WO 2005/113704, May 18, 2004