TY - JOUR A1 - Gumpert, Fabian A1 - Janßen, Annika A1 - Brabec, Christoph J. A1 - Egelhaaf, Hans-Joachim A1 - Lohbreier, Jan A1 - Distler, Andreas T1 - Predicting layer thicknesses by numerical simulation for meniscus-guided coating of organic photovoltaics JF - Engineering Applications of Computational Fluid Mechanics N2 - To achieve maximum efficiency in organic photovoltaics (OPV), functional layers with uniform and exactly predefined thickness are required. An in-depth understanding of the coating process is therefore crucial for an accurate process control. In this paper, the meniscus-guided blade coating process, which is the most commonly used process for the manufacturing of organic electronics, is investigated by experimental and numerical methods. A computational fluid dynamics (CFD) model is created to simulate the coating behaviour of P3HT:O IDTBR, an industrial state-of-the-art active material system used in OPV, and its results' independence of numerical parameters is ensured. In particular, the influence of the coating velocity and the initially injected fluid volume on the resulting wet film thickness is studied. The developed CFD analysis is able to reproduce the experimental results with very high accuracy. It is found that the film thickness follows a power law dependence on the velocity (˜v 2/3) and a linear dependence on the ink volume (˜V). Accordingly, an analytical expression based on our theoretical considerations is presented, which predicts the wet film thickness as a function of the coating velocity and the ink volume only based on easily accessible ink properties. Consequently, this CFD model can effectively substitute time-consuming and expensive experiments, which currently have to be performed manually in the laboratory for a multitude of novel material systems, and thus supports highly accelerated material research. Moreover, the results of this work can be used to achieve homogeneous large-area coatings by utilising accelerated blade coating. Y1 - 2023 U6 - https://doi.org/10.1080/19942060.2023.2242455 SN - 1994-2060 VL - 17 IS - 1 PB - Informa UK Limited ER - TY - JOUR A1 - Gumpert, Fabian A1 - Janßen, Annika A1 - Basu, Robin A1 - Brabec, Christoph J. A1 - Egelhaaf, Hans-Joachim A1 - Lohbreier, Jan A1 - Distler, Andreas T1 - On the theoretical framework for meniscus-guided manufacturing of large-area OPV modules JF - Progress in Organic Coatings N2 - Although the formation of plasma electrolytic oxidation (PEO) coatings on aluminum alloys can significantly enhance their service life, they may still suffer from corrosion damage when exposed to harsh environments with strong corrosivity for a long time. In this work, chitosan (CS) was dissolved in four acids, i.e. hydrochloric acid (HCl), citric acid (CA), lactic acid (LA), and acetic acid (HAc), and deposited onto the PEO-coated 5052 aluminum alloy using dip coating method. Scanning electron microscope (SEM), energy dispersive spectrometer (EDS), atomic force microscope (AFM), contact angle (CA) meter, grazing incidence X-ray diffraction (GIXRD), Fourier transform infrared spectrometer (FTIR), and electrochemical workstation system were used to explore the enhancement of the corrosion resistance of PEO-coated 5052 aluminum alloy by application of CS film prepared in different solvent acids. The results showed that the interactions between chitosan and acid ions affects the uniformity, hydrophobicity, thickness and surface roughness of the CS/PEO coating. The HAc-CS/PEO coating had the lowest surface roughness of 32.4 ± 3.9 nm, the largest contact angle of 85.7 ± 2.0◦, and the thickest CS film of 20 μm, which significantly improved corrosion resistance of PEO-coated aluminum alloy. Y1 - 2024 U6 - https://doi.org/10.1016/j.porgcoat.2024.108505 SN - 0300-9440 VL - 192 PB - Elsevier BV ER -