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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 76: Organic semiconductors II (joint session HL/CPP)
CPP 76.6: Vortrag
Mittwoch, 18. März 2020, 17:00–17:15, POT 112
Electron paramagnetic resonance in OLEDs based on dual-emitting host-guest systems — •Felix Braun1, Tobias Grünbaum1, Wolfram Ratzke1, Sebastian Bange1, Sigurd Höger2, and John M. Lupton1 — 1Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany — 2Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany
OLEDs exhibit strong sensitivity to magnetic fields due to spin-dependent electron-hole recombination. Employing the dual-emitting host-guest system CBP:DB, we can optically assess the spin-permutation symmetry of charge-carrier pairs by their magnetic-field dependent electroluminescence.
We monitor the interconversion between singlet-like and triplet-like populations under electron paramagnetic resonance (EPR) conditions and observe the anticipated anticorrelation in the behaviour of singlet-like and triplet-like carrier pairs. Furthermore, using a deuterated counterpart of the dual-emitting system, we can verify the influence of the hyperfine fields on the linewidth of the EPR signal. We anticipate that altering the spatial distribution of hyperfine interactions between host and guest will allow us to pinpoint the molecular site on which a charge-carrier pair is formed by analysing the EPR linewidth. With the spin-sensitivity introduced by the dual emitter, we even hope to determine whether, e.g., a singlet-like carrier pair preferentially forms on the guest emitter or on the host matrix.