Dresden 2020 – wissenschaftliches Programm
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CPP 86.11: Vortrag
Donnerstag, 19. März 2020, 12:15–12:30, ZEU 260
What is the effective electrical bandgap of an OLED? — •Axel Fischer, Jinhan Wu, and Sebastian Reineke — Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute of Applied Physics, TU Dresden
Organic light-emitting diodes (OLEDs) are used since several years in commercial products, such as displays. However, there are still open questions. For example, there is a lack of studies about the (effective) electrical bandgap of state-of-the-art OLEDs although it is quite important to know the energy that free charge carriers have to overcome before they can recombine. Here, we illuminate OLEDs with UV light which results in generation of free charge carriers that create an open-circuit voltage similar to what one typically observes for solar cells. A comprehensive analysis of temperature dependent measurements then allows to determine an effective electrical bandgap that will be compared to the energy levels of the molecules used in the investigated OLED [Wu et al., Adv. Opt. Mater. 2019, 7, 1801426]. The future importance of the results relies in determining voltage losses, both, from internal non-radiative relaxation as well as from charge transport.