Journal of the Korean Applied Science and Technology (한국응용과학기술학회지)

The Korean Society of Applied Science and Technology (한국응용과학기술학회)
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Effect of Stepwise Doping on Performance of Green Phosphorescent Organic Light-Emitting Diodes

단계적 도핑구조에 따른 녹색 인광 유기발광 다이오드의 성능에 미치는 효과에 관한 연구

  • 황교민 (홍익대학교 정보디스플레이공학과) ;
  • 이송은 (홍익대학교 정보디스플레이공학과) ;
  • 이슬비 (홍익대학교 정보디스플레이공학과) ;
  • 윤승수 (성균관대학교 화학과) ;
  • 김영관 (홍익대학교 정보디스플레이공학과)
  • Received : 2014.12.26
  • Accepted : 2015.01.20
  • Published : 2015.03.30
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Abstract

We investigated green phosphorescent organic light-emitting diodes with stepwise doping to improve efficiency roll-off and operational lifetime by efficient distribution of triplet excitons. The host material which was 4,4,N,N'-dicarbazolebiphenyl (CBP) of bipolar characteristic that can control the carrier in emitting layer (EML). When the EML devided into four parts with different doping concentration, each devices shows various efficiency roll-off and lifetime enhancement. The distribution of the carrier and excitons in the EML can be confirmed by using stepwise doping structure. The properties of device C exhibited luminous efficiency of 51.10 cd/A, external quantum efficiency of 14.88%, respectively. Lifetime has increased 73.70% compared to the reference device.

본 연구에서는 발광층의 전자와 정공의 재결합 영역을 확인하고, 단계적 도핑구조를 이용하여 여기자들의 효율적인 분배를 통해 roll-off 효율을 감소시켜서 녹색 인광 유기발광다이오드의 수명 증가를 나타냈다. 발광층 내 호스트는 양극성의 4,4,N,N'-dicarbazolebiphenyl (CBP)를 사용하여 전하의 이동을 원활하게 하였다. 발광층을 네 구역으로 분할하여 각각 소자를 제작하였고, 네 구역의 도판트 농도에 따라 발광효율과 수명 향상을 보였다. 이로써 발광층 내의 단계적 도핑구조를 이용하여 캐리어와 여기자들이 원활하게 분배된 것을 확인하였다. 기준소자 대비 발광층의 도판트 농도를 5, 7, 11, 9% 순서로 단계적 도핑구조를 적용한 device C의 수명이 약 73.70% 증가하였고, 휘도 효율은 51.10 cd/A와 외부 양자 효율은 14.88%의 성능을 보였다.

Keywords

References

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