Current Applied Physics

Korean Physical Society (한국물리학회)
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Electrical characteristics and efficiency of organic light-emitting diodes depending on hole-injection layer

Lee, Y.H.;Kim, W.J.;Kim, T.Y.;Jung, J.;Lee, J.Y.;Park, H.D.;Kim, T.W.;Hong, J.W.

  • Published : 20070500
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Abstract

In a device structure of ITO/hole-injection layer/N,N0-biphenyl-N,N0-bis-(1-naphenyl)-[1,10-biphthyl]4,40-diamine(NPB)/tris(8-hydroxyquinoline)aluminum(Alq3)/Al, we investigated the eect of the hole-injection layer on the electrical characteristics and externalquantum eciency of organic light-emitting diodes. Thermal evaporation was performed to make a thickness of NPB layer with a rate of0.51.0 A˚/s at a base pressure of 5· 10. 6 Torr. We measured currentvoltage characteristics and external quantum eciency with asuch as good mechanical junction, reducing the operating voltage, and energy band adjustment. Compared with devices without ahole-injection layer, we found that the optimal thickness of NPB was 20 nm in the device structure of ITO/NPB/Alq3/Al. By using aCuPc or PVK buer layer, the external quantum eciencies of the devices were improved by 28.9% and 51.3%, respectively.

Keywords

References

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