Study on a set of bis-cyclometalated Ir(III) complexes with a common ancillary ligand.
Bis-cyclometalated iridium(III) complexes [Ir(F2ppy)2ZN] (FZN), [Ir(F2CNppy)2ZN] (FCZN), [Ir(DMAF2ppy)2ZN] (FDZN) and [Ir(MeOF2ppy)2ZN] (MeOFZN) (F2ppy = 4',6'-difluoro-2-phenylpyridinate, F2CNppy = 5-cyano-4',6'-difluoro-2-phenylpyridinate, DMAF2ppy = 4',6'-difluoro-4-dimethylamino-2-phenylpyridinate, MeOF2ppy = 4',6'-difluoro-4-methyl-2-phenylpyridinate and ZN = 3,5-dimethylpyrazole-N-carboxamide) emitting in the sky blue region were synthesized. We studied the effect of the ancillary ligand ZN and the substituents on the cyclometalating ligands on the crystal structures, photophysical and electrochemical properties and the frontier orbitals. Density functional theory (DFT) calculation results indicate that in FCZN and FDZN the cyclometalating ligands show negligible participation in the HOMO, the ancillary ligand ZN being the main participant along with the Ir(III) d-orbitals. MeOFZN exhibits the maximum photoluminescence quantum efficiency and radiative emission rates along with the dominant low frequency metal-ligand vibrations and maximum reorganization energy in the excited state. All the substituted complexes show more polar characteristics than FZN, FCZN possessing the highest dipole moment among the complexes. The performances of the solution-synthesised organic light emitting devices (OLEDs) of FZN, FCZN and FDZN doped in a blend of mCP (m-bis(N-carbazolylbenzene)) and polystyrene are studied.
Byun
Younghun
Y
Samsung Advanced Institute of Technology, P. O. Box 111, Suwon, 440-600, Korea.
Jeon
Woo Sung
WS
Lee
Tae-Woo
TW
Lyu
Yi-Yeol
YY
Chang
Seok
S
Kwon
Ohyun
O
Han
Eunsil
E
Kim
Heekyung
H
Kim
Myeongsuk
M
Lee
Ha-Jin
HJ
Das
Rupasree Ragini
RR
D018360:Crystallography, X-Ray; D004563:Electrochemistry; D004579:Electron Transport; D004583:Electrons; D007495:Iridium / Q000737:chemistry*; D008024:Ligands; D049449:Luminescence; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry; D011789:Quantum Theory; D013696:Temperature
D008024:Ligands; D009942:Organometallic Compounds; D011137:Polystyrenes; D011725:Pyridines; D007495:Iridium; C023666:pyridine