Journal of the Semiconductor & Display Technology (반도체디스플레이기술학회지)

The Korean Society Of Semiconductor & Display Technology (한국반도체디스플레이기술학회)
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Fabrication of Fine Organic Thin-Film Stripes Using a Hydrophobic Needle

소수성 Needle을 이용한 미세 유기 박막 Stripe 제작

  • 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)
  • 김종명 (한국기술교육대학교 전기.전자.통신공학부) ;
  • 이진영 (한국기술교육대학교 창의융합공학협동과정) ;
  • 신동균 (한국기술교육대학교 전기.전자.통신공학부) ;
  • 박종운 (한국기술교육대학교 전기.전자.통신공학부)
  • Received : 2020.03.11
  • Accepted : 2020.03.20
  • Published : 2020.03.31
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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

References

  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. https://doi.org/10.1002/pi.5902
  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. https://doi.org/10.1021/am506987w
  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. https://doi.org/10.1021/acs.langmuir.8b02659
  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. https://doi.org/10.1109/TED.2019.2947565