MoOx modified Ag anode for top-emitting organic light-emitting devices

Efficient top-emitting organic light-emitting devices (TOLEDs) using a thin MoOx layer modified Ag as the effective hole-injection anode are demonstrated. With tris-(8-hydroxy quinoline)aluminum as emitting layer and trilayer LiF/Al/Ag as semitransparent cathode, the Ag/MoOx based TOLED shows a tune-on voltage of 2.67 V and a maximum current efficiency of 7.27 cd/A, which are much better than those (3.92 V, 6.12 cd/A) obtained from Ag/Ag2O based TOLED and those (5.25 V, 3.5 cd/A) obtained from the corresponding bottom-emitting organic light-emitting devices. Contact potential difference measurement shows that the work function of Ag/MoOx is higher than those of Ag/Ag2O and ozone-treated indium tin oxide, leading to a stronger hole injection. The good performance of Ag/MoOx based TOLED is attributed to the efficient hole injection from the Ag/MoOx anode as well as a microcavity effect. (c) 2006 American Institute of Physics.