Effects of nitridation time on top-emission inverted organic light-emitting diodes

A top-emission inverted organic light-emitting diode (TEIOLED) was fabricated by using Al/AlNx layer as the cathode in the device structure of glass/Al/AlNx/AlQ3/NPB/MTDATA/Au/Ag, where AlNx ultra-thin layer was obtained from Al layer under 90 W microwave plasma treatments in Ar and N2 mixed-gas environment. The N2/Ar ratio and plasma treatment time were adjusted to obtain the maximum luminance and efficiency of 1206 cd/m2 and 0.51 cd/A, respectively, both at 17 V. The AlNx layer surface after plasma treatment was examined by atomic force microscope (AFM) to study the effects of surface roughness on the electroluminescent (EL) characteristics. The thickness of AlNx layer also affected EL results apparently.