Mo O x modified Ag anode for top-emitting organic light-emitting devices

Abstract

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 2.67V and a maximum current efficiency of 7.27cd∕A, which are much better than those (3.92V, 6.12cd∕A) obtained from Ag∕Ag2O based TOLED and those (5.25V, 3.5cd∕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.