Dependence of Carrier Transport Properties on Cathode Metals in PVCz Double-Layered Organic EL Devices

Abstract

PVCz double-layered organic EL devices with negative electrodes using magnesium, strontium and silver metals have been fabricated and dependence of electroluminescent characteristics on the cathode metal has been studied. The device structure is such as ITO/PVCz/PVCz: perylene/Metal. Luminance of 1000 cd/m^2 has been obtained for the devices without electron transport molecules in the layer adjacent to the negative electrode. Dependencies of threshold voltage of electroluminescence emission and barrier height at negative electrode on the metal work function have been clearly observed from the luminance-voltage characteristics and from the charge transport analysis based on Fowler-Nordheim plot, respectively.