Dresden 2017 – wissenschaftliches Programm
CPP 7: Organic Electronics and Photovoltaics I: Light-Emitting Devices (joint session CPP/DS/HL, organized by CPP)
CPP 7.8: Vortrag
Montag, 20. März 2017, 12:45–13:00, ZEU 260
Optical Detection of the Magnetic Field Effect in OLEDs with Metal-Free Dual Singlet-Triplet Emitters — •Wolfram Ratzke1, Lisa Schmitt2, Hideto Matsuoka2, Christoph Bannwarth2, Marius Retegan3, Jonas Zipfel1, Sebastian Bange1, Philippe Klemm1, Frank Neese3, Stefan Grimme2, Olav Schiemann2, John Lupton1, and Sigurd Höger2 — 1University of Regensburg, Germany — 2University of Bonn, Germany — 3MPI Mühlheim an der Ruhr, Germany
Even though the magnetic field effect of organic light emitting diodes (OLEDs) has been investigated for more than one decade it is still difficult to identify the underlying mechanisms. Furthermore, theories are discussed which are based on the magnetic field dependent formation of singlet and triplet excited states in order to explain the change in the device resistance without a simultaneous experimental access to all three observables. The spin states can be measured by detecting the fluorescence and phosphorescence but so far this was always restricted to the exclusive observation of pure singlet or triplet emission by investigating different molecular systems, and hence a coherent statement is not possible. Recently, we have developed metal-free OLED emitters which exhibit simultaneous fluorescence and phosphorescence, even at room temperature. These materials can give insight into the change of spin-state statistics when an external magnetic field is applied, and offer a new perspective to distinguish between different field regimes and spin-dependent mechanisms which lead to the magnetic field effect.