Effects of surface morphology of ITO thin film on the instability of organic light emitting diodes

Surface roughness of ITO (Indium Tin Oxide) was measured by AFM (Atomic Force Microscope) and the existence of spikes was verified. Then OLED (Organic Light Emitting Diode) devices made from those substrates were fabricated and their electrical properties were measured with an I-V measurement system. There is considerable difference in the reverse leakage current of OLEDs depending on the surface roughness of the substrate. We observed a good correlation of reverse leakage current with Rpv (Peak-to-Valley roughness), but the correlations between reverse leakage current and Ra (Average roughness) and Rrms (Root-Mean-Square roughness) are not as good.