Effect of O-2 plasma treatment on hole-injection enhancement for organic light-emitting devices with transparent Au : Al anodes

Abstract

Ali An : ultrathin Al layer is investigated as the anode for organic light-emitting devices (OLEDs). However, without surface modification of the An or An : ultrathin Al anode, the OLED usually exhibits poor performance. Therefore, to obtain good performance of OLED, we applied an O-2 plasma treatment after Al deposition on the An anode. The O-2 plasma treatment of the ultrathin Al layer can greatly enhance the hole injection ability compared with anodes using only An or An : ultrathin Al without O-2 plasma treatment. The OLED using the Au : O-2 plasma pretreated ultrathin Al layer anode demonstrate improved current density and luminance characteristics compared with other anodes, such as Au or An : ultrathin Al without O-2 plasma treatment. The driving voltages of our devices with An only, An : Al, and An : pre-treated Al anode devices are about 18.5 V, 16 V, and 6.6 V, respectively, at a current density of 100 mA/cm(2). The voltages to obtain a luminance of 1000 cd/m(2) for An only and An : pre-treated Al anode devices are needed approximately 18.7 V and 6.5 V, respectively.