Synthesis and characterization of heptaflurosulfonyl-substituted iridium complexes for blue phosphorescent organic light emitting diodes

Abstract

We synthesized the heptaflurosulfonyl-substituted iridium complexes with SOCF(7)pic, SOCF(7)mpic, and SOCF(7)taz as a dopants for blue phosphorescent organic light emitting diodes (PHOLEDs). The SOCF(7)pic, SOCF(7)mpic, and SOCF(7)taz showed high thermal stability with thermal decomposition temperature of 395, 396, and 411 degrees C by the TGA measurement. Using newly synthesized dopants, blue emissive PHOLEDs were fabricated by using co-host materials during vacuum process. The devices with SOCF(7)pic or SOCF(7)mpic dopant exhibited similar current efficiencies (1.55 cd/A vs. 1.25 cd/A) and power efficiencies (1.24 lm/W vs. 1.0 lm/W). It showed relatively higher than the SOCF(7)taz doped device efficiencies with 1.0 cd/A and 0.6 lm/W. The high efficiencies of the SOCF(7)pic and SOCF(7)mpic doped devices compared with the SOCF(7)taz doped device are caused by the improved electrons and holes injection into the emitting layer with well-aligned HOMO-LUMO levels or relatively uniform surface morphology.