Effect of Introducing H[sub 2]O Vapor on Properties of RF Sputter-Grown ITO Anode Layer for OLEDs

Abstract

We report the effects of introducing H 2 O vapor on the structural, surface, and electrical properties of radio-frequency (rf) sputtered indium tin oxide (ITO) anode layer for organic light-emitting diodes (OLEDs). By introducing H 2 O vapor during rf sputtering, we obtained an ITO anode film with lower resistivity, higher transmittance, and a smoother surface relative to the conventional rf-sputter-grown ITO anode even though it was grown at a substrate temperature of 200°C. Secondary ion mass spectroscopy analysis clearly shows that OH content in the rf-sputter-grown ITO anode film was significantly increased by adding H 2 O vapor. In addition, the current density-voltage-luminance result of an OLED fabricated on an H 2 O-vapor-incorporated ITO anode showed a lower turn-on voltage and higher luminescence than those of OLEDs fabricated on the reference ITO anode. This suggests that the introduction of H 2 O vapor during rf sputtering is an effective technique employed to improve the ITO anode layer for both top-and bottom-emitting OLEDs.