Berlin 2024 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 25: Molecular Electronics and Excited State Properties II
CPP 25.5: Vortrag
Mittwoch, 20. März 2024, 10:30–10:45, H 0111
Uncovering the influence of OLED host properties on donor-acceptor type TADF emission by single molecule spectroscopy — •Björn Ewald1, Theodor Kaiser1, and Jens Pflaum1,2 — 1Experimental Physics 6, University of Würzburg, 97074 Würzburg — 2CAE Bayern, 97074 Würzburg
Molecular emitters exhibiting thermally activated delayed fluorescence (TADF) define a promising class of materials for implementation in commercial Organic Light Emitting Diodes (OLEDs). Their successful application requires an understanding and control of the microscopic TADF dynamics by the complementary host material, in particular its polarity and rigidity. However, the distinct local host emitter interactions and their consequences, e.g. on the dihedral conformation or the emerging charge transfer states, are often obscured by averaging and superimposed effects of the molecular ensemble for a given host. Hence, we introduce single molecule spectroscopy as a powerful tool for uncovering the relevant host-emitter interactions at the molecular level. Our studies on the donor-acceptor type emitter TXO-TPA embedded in amorphous PMMA, (semi-)crystalline UGH-3 and polar DPEPO reveal distinct single-photon emission properties, characteristic for the respective host and clearly discernible by antibunching, bunching and intensity histogramms of the correlated photon statistics as well as by the individual spectral emission. Disclosing such fundamental relations on the single molecule level marks an important step towards understanding specific host-emitter interactions and their application in future TADF-based OLED technologies.
Keywords: OLED; TADF; organic electronics; photophysics; photon correlation