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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 15: Poster Session I

CPP 15.38: Poster

Montag, 17. März 2025, 19:00–21:00, P4

Investigation of quenching in exciplex OLEDs under variation of the giant surface potential — •Clarisse Henriques, Albin Cakaj, Alexander Hofmann, and Wolfgang Brütting — Institut für Physik, University of Augsburg, Augsburg, Germany

An exciplex is a short-lived excited charge transfer state formed between donor and acceptor molecules of different species, in which under radiative decay a photon is emitted. They can either function as efficient host for emitters or directly as emitter because of their apparent thermally activated delayed fluorescence characteristics. Especially the electron accepting materials tend to show a macroscopic film polarization, which is also referred to as giant surface potential (GSP). The presence of GSP in an organic light emitting diode (OLED) promotes charge injection in the electron transport layer (ETL), but causes the accumulation of holes, which can result in exciton quenching. Consequently, studying the impact on the device is of crucial importance. The main interest lies now on the tunability of this parameter by using the material as a co-host or directly as emitter. We investigate OLEDs with different film thickness of the ETL and emission layer. Additionally, devices of donor and acceptor with different mixing ratios were prepared. The major focus is now on studying these systems by current density-voltage-luminance, photoluminescence (PL) and electroluminescence spectra, impedance spectroscopy and their PL quenching under different bias voltages. Such studies are fundamental to understand the impact of SOP in OLEDs for further improvement.

Keywords: Exciton quenching; Giant Surface Potential (GSP); Impedance spectroscopy; TADF OLEDs; Exciplex