OSA's Digital Library

Journal of Display Technology

Journal of Display Technology

| A JOINT IEEE/OSA PUBLICATION

  • Vol. 8, Iss. 8 — Aug. 1, 2012
  • pp: 444–449

Self-Assembled Microlens on Top of Light-Emitting Diodes Using Hydrophilic Effect for Improving Extraction Efficiency and Increasing Viewing Angle

Hsiang-Chun Wei and Guo-Dung John Su

Journal of Display Technology, Vol. 8, Issue 8, pp. 444-449 (2012)


View Full Text Article

Acrobat PDF (923 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations
  • Export Citation/Save Click for help

Abstract

In this paper, we propose a self-assembled microlens on top of light-emitting diodes (LEDs) based on hydrophilic effect under ultraviolet (UV)/ozone treatment to improve extraction efficiency and to increase viewing angle. The LED chip was encapsulated by polydimethylsiloxane (PDMS) $(n=1.44)$ before the fabrication process of microlens. The microlens was made of transparent negative photoresist SU-8 $(n=1.63)$. The SU-8 photoresist became more hydrophilic after UV/ozone treatment. After hydrophilic zones were produced by using shadow masks and UV/ozone, the substrate with hydrophilic zones was dipped in and out of diluted SU-8 photoresist solution with slow and constant velocity. Meanwhile, a 200-$\mu{\hbox{m}}$ microlens was formed by self-surface tension and cohesion of diluted SU-8. Finally, microlens was hardened after UV curing. This approach is cost effective and low time-consuming. It did not require photo masks, heating, or etch-transfer processes. It's a new fabrication method that can be easily applied to opto-electronic devices. Integrated with LED, microlens can improve extraction efficiency 28% in total power and increase viewing angle 17 degree.

© 2012 IEEE

Citation
Hsiang-Chun Wei and Guo-Dung John Su, "Self-Assembled Microlens on Top of Light-Emitting Diodes Using Hydrophilic Effect for Improving Extraction Efficiency and Increasing Viewing Angle," J. Display Technol. 8, 444-449 (2012)
http://www.opticsinfobase.org/jdt/abstract.cfm?URI=jdt-8-8-444


Sort:  Year  |  Journal  |  Reset

References

  1. W.-C. Chen, T.-T. Lai, M.-W. Wang, H.-W. Hung, "An optimization system for LED lens design," Expert Syst. With Appl. 38, 11976-11983 (2011).
  2. A. Bateni, S. Laughton, H. Tavana, S. Susnar, A. Amirfazli, A. Neumann, "Effect of electric fields on contact angle and surface tension of drops," J. Colloid and Interface Sci. 283, 215-222 (2005).
  3. S. M. Kuo, C. H. Lin, "Fabrication of aspherical SU-8 microlens array utilizing novel stamping process and electro-static pulling method," Opt. Express 18, 19114-19119 (2010).
  4. Z. Zhan, K. Wang, H. Yao, Z. Cao, "Fabrication and characterization of aspherical lens manipulated by electrostatic field," Appl. Opt. 48, 4375-4380 (2009).
  5. K. Y. Chen, H. Y. Lin, M. K. Wei, J. H. Lee, Y. T. Hsiao, C. C. Lin, Y. H. Ho, J. H. Tsai, "Enhancement and saturation phenomena on luminous current and power efficiencies of organic light-emitting devices by attaching microlens array films," J. Display Technol. 7, 242-249 (2011).
  6. S. Moller, S. Forrest, "Improved light out-coupling in organic light emitting diodes employing ordered microlens arrays," J. Appl. Phys. 91, 3324 (2002).
  7. H. A. Biebuyck, G. M. Whitesides, "Self-organization of organic liquids on patterned self-assembled monolayers of alkanethiolates on gold," Langmuir 10, 2790-2793 (1994).
  8. D. M. Hartmann, O. Kibar, S. G. Esener, "Characterization of a polymer microlens fabricated by use of the hydrophobic effect," Opt. Lett. 25, 975-977 (2000).
  9. H. Ottevaere, R. Cox, H. P. Herzig, T. Miyashita, K. Naessens, M. Taghizadeh, R. Völkel, H. Woo, H. Thienpont, "Comparing glass and plastic refractive microlenses fabricated with different technologies," J.Opt. A: Pure Appl. Opt. 8, S407 (2006).
  10. O. P. Parida, N. Bhat, "Characterization of optical properties of SU-8 and fabrication of optical components," Int. Conf. on Opt. and Photon. (CSIO) (2009).
  11. S.-M. Kuo, C.-H. Lin, "Fabrication of aspherical SU-8 microlens array utilizing novel stamping process and electro-static pulling method," Opt. Express 18, 19114-19119 (2010).
  12. C.-J. Chang, C.-S. Yang, L.-H. Lan, P.-C. Wang, F.-G. Tseng, "Fabrication of a SU-8-based polymer-enclosed channel with a penetrating UV/ozone-modified interior surface for electrokinetic separation of proteins," J. Micromechan. Microeng. 20, (2010) 115031.
  13. H. Hillborg, N. Tomczak, A. Olah, H. Schonherr, G. J. Vancso, "Nanoscale hydrophobic recovery: A chemical force microscopy study of UV/ozone-treated cross-linked poly (dimethylsiloxane)," Langmuir 20, 785-794 (2004).

Cited By

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited