Plasma damage-free sputtering of indium tin oxide cathode layers for top-emitting organic light-emitting diodes

Abstract

We report on plasma damage-free sputtering of an indium tin oxide (ITO) cathode layer, which was grown by a mirror shape target sputtering (MSTS) technique, for use in top-emitting organic light-emitting diodes (TOLEDs). It is shown that OLEDs with ITO cathodesdeposited by MSTS show much lower leakage current ( 9.2 × 10 − 5 mA ∕ cm 2 ) at reverse bias of − 6 V as compared to that ( 1 × 10 − 1 – 10 − 2 mA ∕ cm 2 at − 6 V ) of OLEDs with ITO cathodesgrown by conventional dc magnetron sputtering. Based on high-resolution electron microcopy, x-ray diffraction, and scanning electron microscopy results, we describe a possible mechanism by which plasma damage-free ITO films are grown and their application for TOLEDs.