Synthesis of 5,6-Dihydro[l,10]phenanthroline Derivatives and Their Properties as Hole-Blocking Layer Materials for Phosphorescent Organic Light-Emitting Diodes

摘要

To develop new hole-blocking materials for phosphorescent organic light-emitting diodes (PhOLEDs),5,6-dihydro-2,9-diisopropyl-4,7-diphenyl[l,10]phenanthroline (1) and 5,6-dihydro-2,9-diisopropyl-4-(4-meth-oxyphenyl)-7-phenyl[l,10]phenanthroline (2) were synthesized.While the absorption spectrum of 1 is very similar to that of 2,the photoluminescence spectrum of 1 has the feature of the narrower and blue-shifted blue-violet emission at the peak of 356 nm compared to that of 2.The HOMO and LUMO energy levels of 1 and 2 were estimated from the measurement of cyclic voltammetry,and 1 has the appropriate levels for a hole-blocking layer (HBL).The use of 1 as a HBL in a green PhOLED led to good efficiency of 23.6 cd/A at 4.4 mA/cm~2.