Journal of the Korean Institute of Electrical and Electronic Material Engineers (한국전기전자재료학회논문지)

The Korean Institute of Electrical and Electronic Material Engineers (한국전기전자재료학회)
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Improvement of Outcoupled Light Efficiency of Organic Light-emitting Diodes with a Use of Microlens Array

마이크로 렌즈 어레이를 이용한 유기 발광 소자의 광추출 효율 향상에 관한 연구

  • Kim, Hye Sook (Department of Information Display Engineering, Hongik University) ;
  • Hwang, Deok Hyeon (Department of Information Display Engineering, Hongik University) ;
  • Hong, Jin Woong (Department of Electrical Engineering, Kwangwoon University) ;
  • Song, Min Jong (Department of Radiation Technology, Gwangju Health University) ;
  • Han, Wone Keun (Department of Information Display Engineering, Hongik University) ;
  • Kim, Tae Wan (Department of Information Display Engineering, Hongik University)
  • 김혜숙 (홍익대학교 정보디스플레이공학과) ;
  • 황덕현 (홍익대학교 정보디스플레이공학과) ;
  • 홍진웅 (광운대학교 전기공학과) ;
  • 송민종 (광주보건대학 방사선과) ;
  • 한원근 (홍익대학교 정보디스플레이공학과) ;
  • 김태완 (홍익대학교 정보디스플레이공학과)
  • Received : 2014.03.28
  • Accepted : 2014.04.11
  • Published : 2014.05.01
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Abstract

Because of a waveguiding effect and total internal reflection caused by a difference in refractive indices, only 20% of generated light is emitted to the air and the rest is trapped or absorbed in the device. An improvement of outcoupled efficiency of organic light-emitting diodes was studied using a microlens array. Mold of microlens array was fabricated by using photo-lithography with the AZ9260 photoresist, and the microlens array was formed onto the glass substrate using the UV curing agent named ZPU13-440. Device structure consists of microlens/glass/ITO/TPD/$Alq_3$/LiF/Al. It was found that there is an improvement of external quantum efficiency by about 20% at the same current density for the device with the microlens array compared to that of the reference one. Simulated outcoupled efficiency shows the improvement by about 20% for the device with the microlens array compared to that of the reference one. These results are consistent with the experimental ones.

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References

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