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.

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A basic solution‐processable organic light‐emitting diode (OLED) stack comprising two organic layers is presented in this study. The hole injection layer (poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate), PEDOT:PSS) is slot die coated and flexographically printed for process comparison in terms of film homogeneity and the device performance. The emissive layer consisting of a small molecule host–guest system with a green triplet emitter is slot die coated. The single layer thicknesses are mapped by an in‐house developed imaging color reflectometry enabling the precise measurement of the layer thicknesses over the whole coating area (>50 cm2). Luminance, current density, and light and current efficiency are defined for two different pixel sizes with the active area of 6 × 4 and 14 × 14 mm2. A total of 100 OLEDs are measured showing a very low standard deviation for the different pixels. The solely slot die coated OLEDs show much higher current and power efficiency than the OLEDs with flexographically printed PEDOT:PSS. Small molecule OLEDs reach efficiencies up to 30 cd A−1 and 8 lm W−1. Additionally OLED demonstrators with an active area of ≈27 cm2 are fabricated.

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