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

Abstract

We synthesized the heptaflurosulfonyl-substituted iridium complexes with SOCF7pic, SOCF7mpic, and SOCF7taz as a dopants for blue phosphorescent organic light emitting diodes (PHOLEDs). The SOCF7pic, SOCF7mpic, and SOCF7taz showed high thermal stability with thermal decomposition temperature of 395, 396, and 411 °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 SOCF7pic or SOCF7mpic 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 SOCF7taz doped device efficiencies with 1.0 cd/A and 0.6 lm/W. The high efficiencies of the SOCF7pic and SOCF7mpic doped devices compared with the SOCF7taz 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.