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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 71: Organic Electronics and Photovoltaics - OLEDs and Molecular Excitations

CPP 71.5: Talk

Thursday, March 15, 2018, 16:00–16:15, C 243

Thermal spin polarization of OLEDs observed by correlated fluorescence and phosphorescence in dual emitters — •Tobias Scharff, Jonas Zipfel, Wolfram Ratzke, Sebastian Bange, and John M. Lupton — Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany

In organic light emitting diodes (OLEDs), injected charge carriers can undergo thermal relaxation processes. At low temperatures and high magnetic fields, where the Zeeman energy is comparable with the thermal energy, spin polarization can have a remarkable impact on the spin statistics of the electron-hole recombination process, which is monitored directly by electroluminescence. Here, we sensitize an organic semiconductor with a metal-free phenazine derivative which exhibits simultaneous fluorescence and phosphorescence. This approach allows us to study the impact of spin polarization on spin statistics directly through the ratio of fluorescence and phosphorescence, i.e. in an all-optical manner. Thermal spin polarization leads to an increase in phosphorescence with a concomitant decrease in fluorescence. Besides providing insight into carrier thermalization processes, the approach also offers a route to probing the effect of spin-orbit coupling on spin statistics.