Abstract
Organic light emitting diodes (OLEDs) have great potential for flat panel displays and lighting applications. To make the resulting products more energy-saving, highly-efficient OLEDs are demanded. For all of the OLED thin flims, the electron transporting materials (ETM) consumes energys second only to the emissive layer. Consequently, selection of appropriate ETMs become one of the keys to develop high-efficient OLEDs. In this study, we compare efficiency and lifetimes of devices by dry process for using three respective ETMs, 3,7-Di(1-phenyl-1H-benzo[d]imidazole-2-yl)-5,5-spirofluorenyl-5H-dibenzo[a,d]cyclohe-ptene (BIMS).1,3-bis[3,5-di(pyridin-3-yl)phenyl]benzene (BmPyPb)、and 9,10-bis(3-(pyridine-3-yl)phenyl)anthracene (DPyPA) Taking the green device using co-host system at 1,000 cd/m2 for example, the power efficiency is 27.7、31.7、20.4 lm/W, sequentially. The green device with a single layer of BIMS has the least roll-off power efficiency, and highest lifetimes for 1,188 hrs among them while the one with DPyPA has lower operation voltage than the others. Further, the device using DPyPA as ETL still has lower operation voltage in orange-red devices, and the difference of triplet energy between Ir(ppy)3 and Ir(2-phq)3 makes the performance of BIMS and DPyPA different at 100 cd/m2.