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HL: Fachverband Halbleiterphysik
HL 76: Poster IIIC
HL 76.21: Poster
Donnerstag, 19. März 2020, 15:00–17:30, P2/4OG
Investigating 2D block array for OLED light outcoupling — •Dinara Samigullina1, Paul-Anton Will1, Simone Lenk1, Lydia Galle2, Stefan Kaskel2, and Sebastian Reineke1 — 1Integrated Center for Applied Physics and Photonic Materials, TU Dresden — 2Chair of Inorganic Chemistry I, TU Dresden
Organic Light-Emitting Diodes (OLEDs) have already been established in the industry and have a high potential in the future in backlight-free displays, portable displays and lighting applications. However, to achieve high efficiency, the light outcoupling needs to be improved because the high refractive index of organic materials limits light extraction. Some of the generated light remains trapped in the OLED due to total internal reflection. For this reason, light outcoupling structures are used to extract light from the OLED and increase the External Quantum Efficiency (EQE).
In this work, 2D TiO2 block arrays were implemented to the bottom-emitting OLEDs to increase the amount of extracted light by scattering. Different periods of the blocks were investigated with an ultimate goal to achieve maximum EQE improvement. All the samples with the outcoupling structures showed an efficiency increase. The highest EQE is 23.6% for the blocks with a period of 700 nm and height of 90 nm. The enhancement is 16.3%. Additionally, the effectiveness of the structures, i.e. the fraction of extracted photons, was calculated according to reference [P.-A. Will et al., Adv.Fun.Mat., 29, 1901748 (2019)].