Dresden 2020 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 86: Organic Electronics and Photovoltaics III

CPP 86.10: Talk

Thursday, March 19, 2020, 12:00–12:15, ZEU 260

Multifrequency Spin-Resonance Experiments on Organic LEDs based on Inter- and Intra-molecular Triplet-Singlet Conversion — •Sebastian Weissenseel, Rebecca Bönnighausen, Jeannine Grüne, Nikolai Bunzmann, Vladimir Dyakonov, and Andreas Sperlich — Experimental Physics VI, Julius Maximilian University of Würzburg

The world of organic light emitting diodes (OLEDs) regained a lot of attention with the publication of Goushi et al. in 2012 [1], where the thermal activation of non-radiative triplets via reverse intersystem crossing (RISC) was applied to enhance the fluorescence in OLEDs. This process can be investigated by spin sensitive techniques such as electroluminescence detected magnetic resonance (ELDMR). The idea behind these experiments is that the static magnetic field applied to devices under test modifies only the energy levels of triplet states due to the magnetic moment, resulting in Zeeman splitting, thus changing the emission rates. We observed that resonant microwave radiation, applied to OLEDs by a stripline, led to a change in electroluminescence [2]. Here, we show the difference between inter- and intra-molecular TADF systems by applying a broad range of resonance frequencies. With this method, we gain knowledge about the magnetic field dependence of the linewidth of the ELDMR signal.

[1] Goushi, et al., Nat. Photon. 6, 253 (2012)

[2] Bunzmann et al., arXiv:1906.06073. (2019)