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Open AccessArticle

Comparative Study of Printed Multilayer OLED Fabrication through Slot Die Coating, Gravure and Inkjet Printing, and Their Combination

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Institute of Thermal Process Engineering, Thin Film Technology, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germany
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InnovationLab (iL), Speyerer Strasse 4, 69115 Heidelberg, Germany
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Institute of Printing Science and Technology, TU Darmstadt, Magdalenenstrasse 2, 64289 Darmstadt, Germany
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Light Technology Institute, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germany
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Department of Chemistry, University of Cologne, Luxemburger Strasse 116, 50939 Cologne, Germany
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COPT Center for Organic Electron, University of Cologne, Luxemburger Strasse, 90, 50939 Cologne, Germany
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ZOEK Zentrum für Organische Elektronik Köln gGmbH, Luxemburger Strasse 90, 50939 Cologne, Germany
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Authors to whom correspondence should be addressed.
Colloids Interfaces 2019, 3(1), 32; https://doi.org/10.3390/colloids3010032
Received: 31 January 2019 / Revised: 28 February 2019 / Accepted: 3 March 2019 / Published: 6 March 2019
(This article belongs to the Special Issue Colloids and Interfaces in Printing Technology)
In this study, multilayer organic light-emitting diodes (OLEDs) consisting of three solution-processed layers are fabricated using slot die coating, gravure printing, and inkjet printing, techniques that are commonly used in the industry. Different technique combinations are investigated to successively deposit a hole injection layer (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)), a cross-linkable hole transport layer (N,N′-bis(4-(6-((3-ethyloxetan-3-yl)methoxy)-hexyloxy)phenyl)-N,N′-bis(4-methoxyphenyl)biphenyl-4,4′-diamin (QUPD)), and a green emissive layer (TSG-M) on top of each other. In order to compare the application techniques, the ink formulations have to be adapted to the respective process requirements. First, the influence of the application technique on the layer homogeneity of the different materials is investigated. Large area thickness measurements of the layers based on imaging color reflectometry (ICR) are used to compare the application techniques regarding the layer homogeneity and reproducible film thickness. The total stack thickness of all solution-processed layers of 32 OLEDs could be reproduced homogeneously in a process window of 30 nm for the technique combination of slot die coating and inkjet printing. The best efficiency of 13.3 cd A−1 is reached for a process combination of slot die coating and gravure printing. In order to enable a statistically significant evaluation, in total, 96 OLEDs were analyzed and the corresponding 288 layers were measured successively to determine the influence of layer homogeneity on device performance. View Full-Text
Keywords: OLED; solution-processed; slot die coating; gravure printing; inkjet printing; imaging color reflectometry (ICR) OLED; solution-processed; slot die coating; gravure printing; inkjet printing; imaging color reflectometry (ICR)
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Merklein, L.; Daume, D.; Braig, F.; Schlisske, S.; Rödlmeier, T.; Mink, M.; Kourkoulos, D.; Ulber, B.; Di Biase, M.; Meerholz, K.; Hernandez-Sosa, G.; Lemmer, U.; Sauer, H.M.; Dörsam, E.; Scharfer, P.; Schabel, W. Comparative Study of Printed Multilayer OLED Fabrication through Slot Die Coating, Gravure and Inkjet Printing, and Their Combination. Colloids Interfaces 2019, 3, 32.

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