Nitrogen-oxygen plasma treatment of ITO for performance improvement of blue organic light emitting diodes

摘要

Blue organic light-emitting diodes (OLEDs) were fabricated by pre-treating indium-tin-oxide (ITO) glass with a nitrogen-oxygen plasma (N_2:O_2) carrier gas. The device structure was ITO/α- NPD(4,4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl)/BH140(Idemitsu):BD052(Idemitsu)/BCP (2,9dimethyl-4,7-diphenyl-1,10-phenanthroline) (variable)/LiF/Al:Li. In comparison with conventional O_2-treated devices, our N_2:O_2-treated devices showed increased electroluminescence, current efficiency, brightness, and lifetime. The blue OLED devices showed the optimum working voltage and current density at 5. 5 V when the thickness of the BCP was 25 ? and high efficiency when the thickness was 100 ?.