Transactions on Electrical and Electronic Materials

  • 제6권5호
  • /
  • Pages.233-237
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  • 2005
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  • 1229-7607(pISSN)
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  • 2092-7592(eISSN)
한국전기전자재료학회 (The Korean Institute of Electrical and Electronic Material Engineers)
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Efficiency Improvement of Organic Light-emitting Diodes depending on Thickness of Hole Injection Materials

  • Kim, Weon-Jong (Department of Electrical Engineering, Kawngwoon University) ;
  • Yang, Jae-Hoon (Department of Electrical Engineering, Kawngwoon University) ;
  • Kim, Tag-Yong (Department of Electrical Engineering, Kawngwoon University) ;
  • Jeong, Joon (Department of Electrical Engineering, Kawngwoon University) ;
  • Lee, Young-Hwan (Department of Electrical Engineering, Kawngwoon University) ;
  • Hong, Jin-Woong (Department of Electrical Engineering, Kawngwoon University) ;
  • Park, Ha-Yong (Department of Electrical Engineering, Samcheok National University) ;
  • Kim, Tae-Wan (Department of Physics, Hongik University)
  • 발행 : 2005.10.01
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초록

In the device structure of ITO/hole injection layer/N, N'-biphenyl-N, N'-bis-(1-naphenyl)-[1,1'-biphenyl]4,4'-diamine(NPB)/tris(8-hydroxyquinoline) aluminum$(Alq_3)/Al$, we investigated an effect of hole-injection materials (PTFE, PVK) on the electrical characteristics and efficiency of organic light-emitting diodes. A thermal evaporation was performed to make a thickness of NPB layer with a evaporation rate of $0.5\~1.0\;\AA/s$ in a base pressure of $5\times10^{-6}$ Torr. We measured current-voltage characteristics and efficiency with a thickness variation of hole-injection layer. The PTFE and PVK hole-injection layer improve a performance of the device in several aspects, such as good mechanical junction, reducing the operating voltage and energy band adjustment. Compared with the devices without a hole-injection layer, we have obtained that an optimal thickness of NPB was 20 nm in the device structure of $ITO/NPB/Alq_3/Al$. And using the PTFE or PVK hole-injection layer, the external quantum efficiencies of the devices were improved by $24.5\%\;and\;51.3\%$, respectively.

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참고문헌

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