Novel iridium complexes as high-efficiency yellow and red phosphorescent light emitters for organic light-emitting diodes
A series of novel biscyclometallated iridium complexes based on spirobifluorene ligands and acetyl acetonate (acac) ancillary ligands have been synthesized and characterized. Their electrochemical properties were investigated by cyclic voltammetry (CV). HOMO, LUMO, and energy band gaps of all the complexes were calculated by the combination of UV-vis absorption spectra and CV results. TGA and DSC results indicated their excellent thermal stability and amorphous structure. All the iridium complexes were fabricated into organic light-emitting devices with the device configuration of ITO/PEDOT:PSS (50 nm)/PVK (50 wt %):PBD (40 wt %):Ir complex (10 wt %) (45 nm)/TPBI (40 nm)/LiF (0.5 nm)/Ca (20 nm)/Ag (150 nm). Yellow to red light emission has been achieved from the iridium complexes guest materials. Complex C1 (yellow light emission) achieved an efficiency of 36.4 cd/A (10.1%) at 198 cd/m2 and complex C4 (red light emission) reached external quantum efficiency of 4.6%. The slight decrease of external quantum efficiency at high current density revealed that the triplet-triplet (T1-T1) annihilation was effectively suppressed by the new developed complexes.
Yao, Jun Hong,Zhen, Changgua,Loh, Kian Ping,Chen, Zhi-Kuan
p. 10814 - 10820
(2008/12/23)
SOLUTION PROCESSED ORGANOMETALLIC COMPLEXES AND THEIR USE IN ELECTROLUMINESCENT DEVICES
The invention provides phosphorescent organometallic complexes. The complexes of the invention may be prepared as films further comprising a charge carrying host material may be used at an emissive layer in organic light emitting devices. In one embodiment, the complex is a hyper-branched organoiridium complex comprising a 2-phenylpuridine ligand wherein the phenyl ring or the pyridine ring contains 4 non-hydrogen substituents. In another embodiment, the complex is an organoiridium complex comprising a substituted 2-phenyl pyridine ligand, wherein at least one substituent contains a spiro group.
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Page/Page column 40-41; Sheet 13
(2008/06/13)
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