Berlin 2018 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 71: Organic Electronics and Photovoltaics - OLEDs and Molecular Excitations
CPP 71.4: Vortrag
Donnerstag, 15. März 2018, 15:45–16:00, C 243
The Role of Molecular Environment in Thermally Activated Delayed Fluorescence — •Liudmila G. Kudriashova1, Nikita Drigo2, Sebastian Weissenseel1, Andreas Sperlich1, Mohammad Khaja Nazeeruddin2, and Vladimir Dyakonov1,3 — 1Experimental Physics VI, Julius Maximilian University of Würzburg, 97074 Würzburg, Germany — 2Group for Molecular Engineering of Functional Materials, EPFL, CH-1951 Sion, Switzerland — 3Bavarian Center for Applied Energy Research (ZAE Bayern), 97074 Würzburg, Germany
Thermally activated delayed fluorescence (TADF) opened the way to overcome the efficiency-limiting spin statistics in a new generation of organic light-emitting diodes (OLEDs). Intensity of intramolecular TADF is mainly ruled by conformation of the donor/acceptor parts within the emitter molecule and temperature. At the same time, the role of host matrix is poorly discussed in literature. Here, we report luminescent properties of novel TADF molecules studied in a broad range of temperatures in various types of solid films. We show that emission consists of three components: prompt fluorescence, delayed fluorescence and phosphorescence. Temperature and environment of the TADF emitters have crucial effect on lifetimes and relative amplitudes of the components. Hindering of the emitting molecules in a polymeric matrix suppresses phosphorescence, while increasing both TADF lifetime and intensity a hundredfold. All in all, we demonstrate that the molecular environment can significantly improve TADF efficiency, which is decisive for the resulting OLED performance.