High-color-rendering flexible top-emitting warm-white organic light emitting diode with a transparent multilayer cathode

A top-emitting warm-white organic light emitting diode (TEWOLED) was fabricated with a conductive transparent MAM cathode [MAM = MoO3 (40 nm)/Ag (17 nm)/MoO3 (40 nm)], which had a higher color rendering index (CRI) than that of corresponding ITO-based bottom- emitting organic light-emitting device (OLED). We measured and calculated the optical transmittance of multilayer MAM fabricated on PET substrate by vacuum thermal evaporation. The average transmittance in visible range is above 84%, which is similar to the conventional indium tin oxide (ITO). The weak microcavity effect on the device performance was also studied. MAM multilayer has the potential for using as transparent conductor electrodes for white OLEDs, especially for flexible devices due to its unique optical and electrical properties. (C) 2011 Elsevier B.V. All rights reserved.