Regensburg 2016 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 32: Focus: Triplet States in Organic Optoelectronics I
CPP 32.5: Vortrag
Mittwoch, 9. März 2016, 10:45–11:00, H37
Optical detection of spin states with dual singlet-triplet emitters in OLEDs — •Wolfram Ratzke1, Lisa Schmitt2, Philippe Klemm1, Sebastian Bange1, Sigurd Höger2, and John Lupton1 — 1University Regensburg — 2University Bonn
Doping OLEDs with dual emitters which exhibit simultaneous fluorescence and phosphorescence gives unique insight into spin statistics and dynamics. But bringing dipole forbidden triplets to light without perturbing the excited state of the organic semiconductor of interest and also conserving spin information requires a novel class of emitters. Typical phosphorescent molecules like heavy atom containing metalorganic complexes perturb their vicinity by the external heavy atom effect and destroy spin-coherence. Enhancing spin-orbit coupling by decreasing the singlet-triplet gap as exploited for TADF emitters is of limited utility for optical spin detection since singlet and triplet emission are hardly spectrally distinguishable and enhanced reversed intersystem crossing prevents spin-state preservation. Activating phosphorescence which is spectrally clearly shifted from singlet emission while preserving the spin state requires a more subtle principle. Here, we present metal-free dual emitters with well separated singlet and triplet emission. This separation enables the simultaneous investigation of singlet and triplet decay channels. The emitters can be used as sensing molecules giving a direct reading of the spin states. Changes in spin statistics by external manipulations, i.e. magnetic fields, can be optically detected.