Geometrically isomeric [Ir(C^N)(C’^N’)(N’’^O)-tris-heteroleptic [Ir(dFppy)(CN-ppz)(pic)] Ir(III)-complexes with blue-light: Forwards to efficient blue organic light-emitting diodes

Abstract

Despite the great success of Ir(III)-complex-based green/red-light OLEDs (OLED = organic light-emitting diode), the realization of their efficient blue-OLEDs is far behind and challenging. Herein, using HdFppy (2-(2,4-difluorophenyl)pyridine) and CN-ppzH (4-(1H-pyrazol-1-yl)benzonitrile) as the HC^N/HC’^N’ ligands and Hpic (2-picolinic acid) as the N’’^O-ancillary ligand, the [Ir(C^N)(C’^N’)(N’’^O)]-tris-heteroleptic molecular design strategy was adopted, obtaining the two [Ir(dFppy)(CN-ppz)(pic)]-configured blue-emitting (λPL (photoluminescence emission peak) = 466, 496(sh) nm; ΦPL (photoluminescence quantum efficiency) = 0.41–0.46) geometrical isomers 1a and 1b. Further through the doped and vacuum-deposited fabrication, their blue-OLEDs-1A/1B with the LMax (maximum luminance) values up to 18090–22528 cd/m2 and the ηEQEMax (maximum external quantum efficiency) sizes of 7.99–8.42 %, were realized, respectively. This study result shows that [Ir(dFppy)(CN-ppz)(pic)]-included [Ir(C^N)(C’^N’)(N’’^O)]-tris-heteroleptic Ir(III)-complexes can be used as the attractive blue-phosphor candidates forwards to efficient blue-OLEDs.