Journal of the Semiconductor & Display Technology (반도체디스플레이기술학회지)

The Korean Society Of Semiconductor & Display Technology (한국반도체디스플레이기술학회)
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Fabrication of Cylindrical Microlens Using Slot-die Coating and Thermal Reflow Method

슬롯 다이 코팅과 Thermal Reflow방법을 이용한 Cylindrical 마이크로렌즈 제조

  • Lee, Jinyoung (Interdisciplinary Program in Creative Engineering, Korea University of Technology and Education) ;
  • Park, Jongwoon (School of Electrical & Communication Engineering, Korea University of Technology and Education)
  • 이진영 (한국기술교육대학교 창의융합공학협동과정) ;
  • 박종운 (한국기술교육대학교 전기.전자.통신공학부)
  • Received : 2020.08.20
  • Accepted : 2020.09.11
  • Published : 2020.09.30
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Abstract

A microlens has been fabricated by various methods such as a thermal reflow, hot embossing, diamond milling, etc. However, these methods require a relatively complex process to control the microlens shape. In this work, we report on a simple and cost-effective method to fabricate a cylindrical microlens (CML), which can diffuse light widely. We have employed a slot-die head with the dual plate (a meniscus guide with a protruded μ-tip and a shim with a slit channel) for coating of a narrow stripe using poly(methyl methacrylate) (PMMA). We have shown that the higher the coating gap, the lower the maximum coating speed, which causes an increase in the stripe width and thickness. The coated PMMA stripe has the concave shape. To make it in the shape of a convex microlens, we have applied the thermal reflow method. When the stripe thickness is small, however, its effect is negligible. To increase the stripe thickness, we have increased the number of repeated coating. With this scheme, we have fabricated the CML with the width of 223 ㎛ and the thickness of 7.3 ㎛. Finally, we have demonstrated experimentally that the CML can diffuse light widely, a feature demanded for light extraction efficiency of organic light-emitting diodes (OLEDs) and suppression of moiré patterns in displays.

Keywords

References

  1. Ee, Y. et al., "Optimization of Light Extraction Efficiency of III-Nitride LEDs with Self-Assembled Colloidal-Based microlenses," IEEE J. Sel. Top. Quant., Vol. 15, pp. 1218-1225, 2009. https://doi.org/10.1109/JSTQE.2009.2015580
  2. Park, J. B., Shin, D. K., Han, S. G., and Park, J. W., "Enhancement of Light Extraction from Transparent OLED Lighting Panels," J. of The Korean Society of Semiconductor & Display Technology, Vol. 16, pp. 41-45, 2017.
  3. Zhou, L., Dong, X., Lv, G., Chen, J., and Shen, S., "Fabrication of concave microlens array diffuser films with a soft transparent mold of UV-curable polymer," Opt. Commun., Vol. 342, pp. 167-172, 2015. https://doi.org/10.1016/j.optcom.2014.12.071
  4. Yuan, W., Li, L., Lee, W., and Chan, C., "Fabrication of Microlens Array and Its Application: A Review," Chin. J. Mech. Eng., Vol. 31, pp. 1-9, 2018. https://doi.org/10.1186/s10033-018-0219-4
  5. O'Neill, F., and Sheridan, J., "Photoresist reflow method of microlens production Part I: Background and experiments," Optik, Vol. 113, pp. 391-404, 2002. https://doi.org/10.1078/0030-4026-00186
  6. Bae, S., Kim, K., Yang, S., Jang, K., and Jeong, K., "Multifocal microlens arrays using multilayer photolithography," Opt. Express, Vol. 28, pp. 9082-9088, 2020. https://doi.org/10.1364/OE.388921
  7. Gschrey, M. et al., "Highly indistinguishable photons from deterministic quantum-dot microlenses utilizing three-dimensional in situ electron-beam lithography," Nat. Commun., Vol. 6, 7662, 2015. https://doi.org/10.1038/ncomms8662
  8. Chen, L., and Bonaccurso, E., "Effects of surface wettability and liquid viscosity on the dynamic wetting of individual drops," Phys. Rev. E, Vol. 90, 022401, 2014. https://doi.org/10.1103/PhysRevE.90.022401