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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 28: Poster III
CPP 28.10: Poster
Mittwoch, 20. März 2024, 11:30–13:30, Poster C
Transient electroluminescence and current studies on TADF-based OLEDs — •Thomas Fleischmann1, Björn Ewald1, and Jens Pflaum1,2 — 1University of Würzburg, Faculty of Physics and Astronomy, Experimental Physics VI, 97074 Würzburg — 2CAE Bayern, 97074 Würzburg
The external quantum efficiency of Organic Light Emitting Diodes (OLEDs) is limited by long-living dark triplet states of conventional fluorophores. This restriction can be lifted by an efficient reverse intersystem crossing (RISC) process which converts non-emissive triplet states into emissive singlet states. This process is prominent in thermally activated delayed fluorescence (TADF) emitters, where the singlet-triplet energy splitting is on the order of thermal energy at room temperature. However, the utilization of TADF emitters comes at the expense of a delayed fluorescence at significantly lower decay rates and a high sensitivity of the photodynamics on the local emitter-host interactions. In this contribution, we analyze the transient behavior of TADF-based OLEDs by applying voltage pulses and recording the time-resolved electroluminescence and current. Comparing these time-resolved properties we conclude on capacitive effects in our OLEDs, e.g. induced by the Schottky-barriers at the contact interfaces, and the photodynamics of the molecular emitters.
Keywords: OLED; TADF; transient electroluminescence; emitter; photophysics