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High efficient green electroluminescence of iridium(III) complexes using (1H-pyrazol-5-yl)pyridine derivatives as ancillary ligands with low efficiency roll-off

Abstract

Four iridium(III) complexes namely Ir-me, Ir-cf3, Ir-py and Ir-ph were synthesized, in which 2-(4-trifluoromethyl)phenylpyridine (tfmppy) was used as main ligand and 2-(3-methyl-1H-pyrazol-5-yl)pyridine (mepzpy), 2-(3-(trifluoromethyl)-1H-pyrazol-5-yl)pyridine (cf3pzpy), 2,2'-(1H-pyrazole-3,5-diyl)dipyridine (pypzpy) and 2-(3-phenyl-1H-pyrazol-5-yl)pyridine (phpzpy) were applied as the ancillary ligands, respectively. All complexes showed similar green light peaked at 494-499 nm with with high phosphorescence quantum efficiency (0.76-0.82). The organic light-emitting diodes (OLEDs) with the structure of ITO/HATCN (hexaazatriphenylenehexacabonitrile) (5 nm)/ TAPC (bis[4-(N,N-ditolylamino)-phenyl]cyclohexane, 50 nm)/Ir complexes (8 wt %): TCTA (4,4’,4’’-tri(9-carbazoyl)triphenylamine, 20 nm)/ TmPyPB (1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, 40 nm)/LiF (1 nm)/Al (100 nm) displayed high current efficiency with low efficiency roll-off. Moreover, the device based on Ir-me complex exhibited the best performances with a maximum luminance of 38155 cd m-2, the maximum current efficiency of 92 cd A-1, a maximum external quantum efficiency of 28.90%. These results suggested that green Ir(III) complexes were obtained by modification of the ppy ligand and rational introduction of (1H-pyrazol-5-yl)pyridine derivatives as the ancillary ligands for high efficient OLEDs.

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Publication details

The article was received on 10 Mar 2018, accepted on 09 May 2018 and first published on 11 May 2018


Article type: Paper
DOI: 10.1039/C8TC01182F
Citation: J. Mater. Chem. C, 2018, Accepted Manuscript
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    High efficient green electroluminescence of iridium(III) complexes using (1H-pyrazol-5-yl)pyridine derivatives as ancillary ligands with low efficiency roll-off

    N. Su, G. Lu and Y. Zheng, J. Mater. Chem. C, 2018, Accepted Manuscript , DOI: 10.1039/C8TC01182F

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