Dependence of Cs-doped electron transport materials on light-emitting characteristics of blue phosphorescent organic light-emitting diodes

摘要

We investigated that the light-emitting performances of blue phosphorescent organic light-emitting diodes with three different electron transport materials, which are partially doped with Cesium(Cs) metal. We found that the device characteristics are very dependent on the nature of the introduced electron transport layer(ETL) such as H0M0/LUM0, triplet energy(T_1), and film morphology. When an appropriate Cs-doped ETL was introduced, external quantum efficiency was enhanced as well as driving voltage was reduced, therefore peak power efficiency improved up to 45.6 lm/W. Moreover, we also compared the device characteristics of blue PHOLEDs with or without LiF between Cs-doped ETL and Al Cathode.