Synthesis, characterization, photophysical and electroluminescent properties of iridium complexes with CF3-substituted 1,3,4-oxadiazole amide ancillary ligands

Abstract

Utilizing 1,3,4-oxadiazole amide that possesses outstanding electron mobility to serve as auxiliary ligands, four novel iridium (III) complexes of Ir1–Ir4 were prepared. Their structure, photophysical, and electrochemical characteristics were examined in detail, and quantum chemical calculations were used to interpret their photophysical behaviors. At room temperature, complexes Ir1 and Ir2 exhibit almost coincident green phosphorescence with peaks at 506 nm. Ir3 and Ir4 complexes produce greenish blue and greenish yellow light with a double-peak structure located at 496 and 531 nm. Organic light-emitting diodes utilizing Ir1–Ir4 as emitters exert extremely moderate efficiency roll-off, which is caused by the emitters bearing CF3-substituted 1,3,4-oxadiazole amide possessing excellent electron mobility.