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Fabrication of Fine Organic Thin-Film Stripes Using a Hydrophobic Needle  

Kim, Jongmyeong (School of Electrical & Communication Engineering, Korea University of Technology and Education)
Lee, Jinyoung (Interdisciplinary Program in Creative Engineering, Korea University of Technology and Education)
Shin, Dongkyun (School of Electrical & Communication Engineering, Korea University of Technology and Education)
Park, Jongwoon (School of Electrical & Communication Engineering, Korea University of Technology and Education)
Publication Information
Journal of the Semiconductor & Display Technology / v.19, no.1, 2020 , pp. 73-78 More about this Journal
Abstract
There appears lateral capillary force in a hydrophilic flat needle employed for the fabrication of fine organic thin-film stripes, bringing in an increase of the stripe width. It also causes the stripe thickness to increase with increasing coating speed, which is hardly observed in a normal coating process. Through computational fluid dynamics (CFD) simulations, we demonstrate that the lateral capillary flow can be substantially suppressed by increasing the contact angle of the needle end. Based on the simulation results, we have coated the outer surface of the flat needle with a hydrophobic material (polytetrafluoroethylene (PTFE) with the water contact angle of 104°). Using such a hydrophobic needle, we can suppress the lateral capillary flow of an aqueous poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS) to a great extent, rendering the stripe narrow (63 ㎛ at 30 mm/s). Consequently, the stripe thickness is decreased as the coating speed increases. To demonstrate its applicability to solution-processable organic light-emitting diodes (OLEDs), we have also fabricated OLED with the fine PEDOT: PSS stripe and observed the strong light-emitting stripe with the width of about 68 ㎛.
Keywords
Needle coating; Hydrophobic needle; Capillary force; OLED; Computational Fluid Dynamics(CFD);
Citations & Related Records
Times Cited By KSCI : 2  (Citation Analysis)
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1 Choi, S., Moon, S., Kim, T., and Kim, H., "Fabrication of Capacitive Yarn Torsion Sensors based on an Electrospinning Coating Method," Polym. Int, Vol. 68, pp. 1921-1927, 2019.   DOI
2 Li, R., Hu, A., Zhang, T., and Oakes, K., "Direct Writing on Paper of Foldable Capacitive Touch Pads with Silver Nanowire Inks," ACS Apl. Mater. Interfaces, Vol. 6, pp. 21721-21729, 2014.   DOI
3 Matatagui, D. et al, "Real-Time Characterization of Electrospun PVP Nanofibers as Sensitive Layer of a Surface Acoustic Wave Device for Gas Detection," J. Nanostruct., Vol. 21, pp. 1-8, 2014.
4 Lee, J., and Park J., "Fabrication of Fine PEDOT:PSS Stripes Using Needle Coating," J. of The Korean Society of Semiconductor & Display Technology, Vol. 18, pp. 100-104, 2019.
5 Li, W., Ji, W., Sun, H., Lan, D., and Wang, Y., "Pattern Formation in Drying Sessile and Pendant Droplet: Interactions of Gravity Settling, Interface Shrinkage, and Capillary Flow," Langmuir, Vol. 35, pp. 113-119, 2018.   DOI
6 Lee, J., Li, X., and Park, J., "Suppression of Capillary Flow in Slot-Die Coating for the Fabrication of Fine OLED Stripe," IEEE Trans. Electron Devices, Vol. 66, pp. 5221-5229, 2019.   DOI