Abstract
We have synthesized 4-[(4-nitrophenyl)ethynyl]benzoic acid (NPBA) as a hole injection material for the modification of ITO surface and fabricated OLEDs consisting of ITO/NPBA self-assembled monolayer (SAM)/TPD (600 Å)/Alq3 (600 Å)/Al (600 Å). The effects of ITO modified with NPBA SAM exhibited lower driving voltage than the device using 4-nitrobenzoic acid (NBA). Also, we have examined the interface properties between the modified ITO and adjacent organic layer from the measurements of contact angle and atomic force microscopy (AFM).
Acknowledgments
This work was supported by the Basic Research Program of the Korea Science & Engineering Foundation (R01-2006-000-10196-0).
Notes
γ s p : polar component, γ: surface energy, the sum of polar and dispersive component.