Enhancement of hole injection using O2 plasma-treated Ag anode for top-emitting organic light-emitting diodes

Abstract

We report the enhancement of hole injection using AgOx layer between Ag anode and 4, 4′ -bis[N-(1-naphtyl)-N-phenyl-amino]biphenyl in top-emitting organic light-emitting diode (OLED). The turn-on voltage of OLEDs decreased from 17 to 7 V as Ag changed to AgOx by the surface treatment using O2 plasma. Synchrotron radiation photoelectron spectroscopy results showed that the work function increased about 0.4 eV by the O2 plasma treatment. This led to the decrease of the energy barrier for hole injection, reducing the turn-on voltage of OLEDs. © 2005 American Institute of Physics.