Dresden 2017 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 52: Devices

HL 52.1: Talk

Wednesday, March 22, 2017, 09:30–09:45, POT 06

Full Range Electrothermal Modeling of Organic Light-emitting Diodes — •Axel Fischer, Koen Vandewal, Simone Lenk, and Sebastian Reineke — Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), TU Dresden

Organic light-emitting diodes (OLEDs) are now considered for lighting and signaling in the automobile sector, but the requirements are harsh. Moreover, cars have to operate at different ambient conditions, but the appearance of the lighting should remain the same. For tail and break lights, extreme brightness is needed (> 10.000 cd/m²) in order to ensure good visibility. As a consequence, high current and power densities are applied which lead to self-heating and unpleasant inhomogeneities of the light emission, neutralizing the benefits of OLED technology such as extraordinary designs. These issues arise due to the fact that OLEDs show a strong dependence between conductivity and temperature, leading to nonlinear electrothermal feedback [Fischer et al., Adv. Funct. Mater., 2014, 24]. Thus, developing accurate electrothermal models for OLEDs is of great interest to establish a future thermal management strategy, holding the brightness as well as its lateral homogeneity constantly high. Here, we present an electrothermal model for OLEDs which nicely matches the full operational range, regarding voltage and temperature and by that is able to reproduce experimentally observed "S"-shaped current-voltage characteristics upon Joule self-heating. Besides that, our approach considers recombination and drift related phenomena, giving valuable insights to the physics of OLEDs.