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DS: Fachverband Dünne Schichten
DS 7: Spins in Molecular Systems: Strategies and Effects of Hyperpolarization
DS 7.4: Vortrag
Mittwoch, 19. März 2025, 10:45–11:00, H14
Analysis of polaron pair lifetime dynamics and secondary processes in exciplex driven TADF OLEDs using organic magnetic field effects (MFE) — •Annika Morgenstern1, Dominik Weber2, Lukas Hertling1,3, Konstantin Gabel1, Ulrich T. Schwarz1, Daniel Schondelmaier2, Dietrich R.T. Zahn1,3, and Georgeta Salvan1,3 — 1Institute of Physics, TU Chemnitz — 2Physical Engineering and Computer Science, WH Zwickau — 3MAIN, TU Chemnitz, Chemnitz
MFE in TADF materials have been shown to influence the reverse intersystem crossing and to impact on electroluminescence and conductivity. Here, we present a novel model combining Cole-Cole and Lorentzian functions to describe low and high MFE originating from hyperfine coupling, the Δg mechanism, and triplet processes. We applied this approach to organic light-emitting devices of third generation based on TCTA and TPBi, exhibiting blue emission, to unravel their loss mechanisms. The quality of the regression function was evaluated using k-fold cross-validation. The scoring was compared to various alternative fitting functions, which were previously proposed in literature. Density functional theory calculations, photoluminescence, and electroluminescence studies validated the formation of a TADF exciplex system. Furthermore, we propose successful encapsulation using a semi-permeable polymer, showing promising results for magnetic field sensing applications. This study provides insights into the origin of MFE in exciplex-TADF materials, with potential applications in optoelectronic devices and sensing technologies.
Keywords: thermally activated delayed fluorescence (TADF); organic magnetic field effects (MFE); triplet processes; OLED; exciplex