Dresden 2020 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 17: Organic Thin Films, Organic-Inorganic Interfaces II (joint session DS/CPP)
DS 17.6: Vortrag
Dienstag, 17. März 2020, 12:30–12:45, CHE 91
Organic light-emitting diodes for high-brightness operation: self-heating and switched-back regions — •Anton Kirch1, Axel Fischer1, Matthias Liero2, Jürgen Fuhrmann2, Annegret Glitzky2, and Sebastian Reineke1 — 1Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute of Applied Physics, Technische Universität Dresden, Germany — 2Weierstrass Institute Berlin, Germany
Nonlinear effects typically involve switching phenomena that can lead to abrupt catastrophic device failure. For example, organic light-emitting diodes (OLEDs) suffer from strong electrothermal feedback that arises upon Joule self-heating. The interaction between temperature-dependent conductivity and power dissipation results in a positive feedback loop that finally destroys the device by thermal runaway. The situation becomes more severe for large-area OLEDs where the operation regime can locally differ. Former modeling studies, using a network of thermistors, led to the proposal that a so-called *switched-back* region arises. In this area, the current density, as well as the brightness, decreases although the total device current still increases when running an IV scan.
Here, we experimentally prove the existence of a switched-back region. We demonstrate that its appearance agrees with the simulation that solely uses electrothermal modeling. Our study aims to improve the long-term stability of high brightness OLED lighting tiles e.g. as applied in the automotive sector.