Journal of the Microelectronics and Packaging Society (마이크로전자및패키징학회지)

The Korean Microelectronics and Packaging Society (한국마이크로전자및패키징학회)
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Effects of Passivation Thin Films on the Optical Properties of the Green Organic Light Emitting Diodes

페시베이션 박막이 녹색 유기발광다이오드의 광학특성에 미치는 영향

  • Mun, Sae Chan (Department of Electronics Engineering, Dankook University) ;
  • Lee, Sang Hee (Department of Electronics Engineering, Dankook University) ;
  • Park, Byung Min (Department of Electronics Engineering, Dankook University) ;
  • Pyee, Jaeho (Department of Molecular Biology, Dankook University) ;
  • Chang, Ho Jung (Department of Electronics Engineering, Dankook University)
  • 문세찬 (단국대학교 공과대학 전자전기공학과) ;
  • 이상희 (단국대학교 공과대학 전자전기공학과) ;
  • 박병민 (단국대학교 공과대학 전자전기공학과) ;
  • 피재호 (단국대학교 자연과학대학 분자생물학과) ;
  • 장호정 (단국대학교 공과대학 전자전기공학과)
  • Received : 2016.01.25
  • Accepted : 2016.03.19
  • Published : 2016.03.30
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Abstract

The organic light emitting diodes (OLEDs) have been studied as large flexible displays, light source and hard wares of internet of things. However, OLEDs show some drawbacks in terms of external environments due to the low work function of the metals and the reactive organic materials. In particular, the operation functions of the OLEDs tend to deteriorate rapidly by exposing the oxygen and moisture. So as to prevent it, domestic and overseas studies underway in various method such as ALD, PVD, CVD. But it has complex process and high cost. Therefore In order to protect devices from the external environments, it is important to develop the passivation thin films of low-cost and simple process which can prevent the devices from the penetration of the oxygen and moistures. In this study, to improve the reliability, passivation thin films were coated onto the green OLEDs by spin coating method and investigated the changes of the optical properties of the prepared devices at various doping concentrations of sodium alginate (SA). The passivation solutions were synthesized by using polyvinyl alcohol (PVA) host material with a dopant of SA which were added with the amounts of 10, 20 and 40 wt% into the PVA. As a result, the best barrier properties of the OLEDs were obtained for the samples with 40 wt% SA. Finally, the passivation films can be optimized by using the mixture solution of PVA and SA materials.

유기발광다이오드(orgianic light emitting diodes, OLEDs)는 대형 유연 디스플레이와 발광원으로서 사물인터넷 (IoT)의 하드웨어 기기 등 다양한 분야에서 연구가 진행되고 있다. 그러나 낮은 일함수의 금속 및 쉽게 반응하는 유기재료 자체의 특성으로 인하여 외부환경에 매우 취약한 단점을 가지고 있으며 특히, 수분과 산소에 민감하여 외부와의 접촉 시 성능이 급속도로 저하되는 현상을 나타내게 된다. 이를 방지하기 위해 PVD, CVD, ALD 와 같은 방법으로 보호막 형성 연구를 진행 중에 있지만 복잡한 공정 및 높은 비용의 문제점 등이 있다. 그러므로 외부 환경에 의한 성능 저하를 차단해주는 저렴하고 단순한 공정의 페시베이션(passivation) 박막 기술 개발이 매우 중요하다. 본 연구에서는 유기발광다이오드의 수명 향상을 위하여 스핀코팅(spin-coating) 방법으로 녹색 유기발광다이오드 소자 위에 조성비에 따른 페시베이션 박막을 형성한 후 녹색 유기발광다이오드의 휘도특성 변화를 조사하였다. 페시베이션 용액은 poly vinyl alcohol (PVA)를 기반으로 sodium alginate (SA)를 0, 10, 20, 40 wt%의 조성비로 제조하였으며, 40 wt%의 조성비에서 가장 좋은 배리어 보호 특성을 나타내었다. 최종적으로 PVA + SA 용액의 최적화된 페시베이션 보호막을 제작할 수 있었다.

Keywords

References

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