Blue phosphorescence organic light emitting diodes with trifluorosulfonyl-substituted iridium complexs for preferential horizontal orientation

Abstract

New blue iridium complexes consist of trifluoromethyl sulfonyl substituent at 3 position on the phenyl ring, and methyl group at the 4 position of the pyridine group as the main ligand and a picolinate (pic), a picolinate with 3-methylpyridine (mpic) as the ancillary ligand for blue phosphorescence organic light emitting diodes (PHOLEDs) have been synthesized. The device with mpic dopant showed higher current, external quantum, and power efficiency of 7.17 cd/A, 3.7%, and 5.29 lm/W compared to that with the pic dopant (4.03 cd/A, 2.78%, and 3.57 lm/W). These improved properties could be explained by the outcoupling effect by relatively horizontally orientated emitter and preventing self-quenching due to triplet-triplet annihilation.