Substituent effects of iridium complexes for highly efficient red OLEDs

Abstract

This study reports substituent effects of iridium complexes with 1-phenylisoquinoline ligands. The emission spectra and phosphorescence quantum yields of the complexes differ from that of tris(1-phenylisoquinolinato-C2,N)iridium(iii)(Irpiq) depending on the substituents. The maximum emission peak, quantum yield and lifetime of those complexes ranged from 598-635 nm, 0.17-0.32 and 1.07-2.34 micros, respectively. This indicates the nature of the substituents has a significant influence on the kinetics of the excited-state decay. The substituents attached to phenyl ring have an influence on a stability of the HOMO. Furthermore, those substituents have effect on the contribution to a mixing between 3pi-pi* and (3)MLCT for the lowest excited states. Some of the complexes display the larger quantum yield than Irpiq, which has the quantum yield of 0.22. The organic light emitting diode (OLED) device based on tris [1-(4-fluoro-5-methylphenyl)isoquinolinato-C2,N]iridium(iii)(Ir4F5Mpiq) yielded high external quantum efficiency of 15.5% and a power efficiency of 12.4 lm W(-1) at a luminance of 218 cd m(-2). An emission color of the device was close to an NTSC specification with CIE chromaticity characteristics of (0.66, 0.34).

A Novel Photopolymerization Initiating System Based on an Iridium Complex Photocatalyst

“…Such Ir complexes have been the subject of extensive works [8] and important applications as phosphorescent dopants in OLEDs fabrication proposed. [8,9] On the other hand, to the best of our knowledge, they have never been mentioned in the photopolymerization area. In this paper, we proposed tris(2-phenylpyridine)-iridium (Ir(ppy) 3 ) as a novel rcPI.…”

High Efficiency and Small Roll‐Off Electrophosphorescence from a New Iridium Complex with Well‐Matched Energy Levels

“…Devices were fabricated with the structure of ITO/NPB (60 nm)/Ir(BPPya) 3 -doped CBP (40 nm)/BPhen (20 nm)/LiF (1 nm)/Al (100 nm), in which Ir(BPPya) 3 worked as the phosphorescent dopant emitter, CBP as the host material, and BPhen was used to serve as the electron-transporting layer. [27] Here, ITO is indium tin oxide, NPB is N,N′-bis- (1-naphthyl)-N,N′-diphenyl,1,1′-biphenyl-4,4′-diamine, and BPhen is 4,7-diphenyl-1,10-phenanthroline. It was found that the best performance was achieved by the device with an Ir(BPPya) 3 doping concentration of 7 % (D1).…”

Organic Semiconductor Electroluminescent Materials

“…When the phenyl is replaced by a naphthyl ring, the Ir(1-niq) 2 (acac) or Ir(2-niq) 2 (acac) formed have emission peaks at 664 and 633 nm, respectively. Ir(4F5Mpiq) 3 was reported in 2005 [161] by the same research team who developed Ir(piq) 3 . The maximum EQE is as high as 15.5 % at a more reasonable current density of 1.23 mA/cm 2 , and the EQE remains at 7.9 % at a current density of 120 mA/cm 2 with luminance of 10,000 cd/m 2 .…”