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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 3: Organic Electronics and Photovoltaics - Layer Morphology and Molecular Aggregation

CPP 3.9: Talk

Monday, March 12, 2018, 12:00–12:15, C 243

Impact of the excitation spot adjustment in angular resolved photoluminescence experiments — •Christian Hänisch, Simone Lenk, and Sebastian Reineke — Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, TU Dresden, Germany

One of the main pathways of optimizing the performance of organic light-emitting diodes (OLED) is the reduction of optical loss modes by aligning the transition dipole moments (TDM) of the light-emitting molecules parallel to the substrate interface.

Angular resolved photoluminescence spectroscopy is the most prominent experimental technique to determine the anisotropy factor as a measure of the average TDM orientation. Despite the widespread application of this method, a quantitative discussion of the impact of specific setup configurations is - to the best of our knowledge - missing so far. Especially, the accurate positioning and size of the optical excitation spot is very important as well as its distance to the detector.

With help of a numerically solved ray optics model, we show that already small displacements of the excitation spot can lead to remarkable changes in the measured emission spectra. For non-ideal setup configurations, the accuracy of experimental data fits can be drastically improved using the developed corrections.

Hence, this work enables not only to numerically treat unavoidable experimental non-idealities such as displacements caused by the substrate thickness but also helps to quantify and state measurement deviations of the anisotropy factor.