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Emission Characteristics of OLEDs Using LiF/Al/LiF Structure

LiF/Al/LiF 구조를 적용한 OLED 소자의 발광 특성

  • Park, Yeon-Suk (Department of Advanced Materials Science and Engineering, Daejin University) ;
  • Yang, Jae-Woong (Department of Advanced Materials Science and Engineering, Daejin University) ;
  • Ju, Sung-Hoo (Department of Advanced Materials Science and Engineering, Daejin University)
  • 박연석 (대진대학교 신소재공학과) ;
  • 양재웅 (대진대학교 신소재공학과) ;
  • 주성후 (대진대학교 신소재공학과)
  • Received : 2010.05.24
  • Accepted : 2010.08.23
  • Published : 2010.09.01

Abstract

We fabricated red and blue organic light emitting display (OLEDs) which had the two kinds of multi-structure of ITO/HIL/HTL/EML/ETL/LiF/Al and ITO/HIL/HTL/EML/ETL/LiF/Al/LiF. In the case of red OLED that had LiF/Al/LiF structure compared to LiF/Al structure, the current density increased from 4.3 mA/$cm^2$ to 7.3 mA/$cm^2$, and the brightness increased from 488 cd/$m^2$ to 1,023 cd/$m^2$ at 7.0 V, and as a result the current efficiency was improved from 11.28 cd/A to 13.95 cd/A. Also in the case of blue OLED that had LiF on Al cathode layer, the current density increased from 1.2 mA/$cm^2$ to 1.8 mA/$cm^2$, and the brightness increased from 45 cd/$m^2$ to 85 cd/$m^2$ at 7.0 V, and as a result the current efficiency was improved from 3.69 cd/A to 4.82 cd/A. Through these experimental results it could be suggested that the LiF layer formed on Al prevents the oxidation of Al surface, and the electrode resistance become low with increase of supplied electrons, therefore the brightness and the efficiency are improved from the influence to the well-balanced bonding of electron and hole at emitting layer.

Keywords

OLED;Structure;Cathode;LiF;Efficiency

Acknowledgement

Supported by : 대진대학교

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