Iridium(III) complexes adopting thienylpyridine derivatives for yellow-to-deep red OLEDs with low efficiency roll-off.
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| Title: | Iridium(III) complexes adopting thienylpyridine derivatives for yellow-to-deep red OLEDs with low efficiency roll-off. |
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| Authors: | Niu, Zhi-Gang1,2, Yan, Li-Ping2, Wu, Lei2, Chen, Guang-Ying2, Sun, Wei2, Liang, Xiao1, Zheng, You-Xuan1 yxzheng@nju.edu.cn, Li, Gao-Nan1,2 ligaonan2008@163.com, Zuo, Jing-Lin1 |
| Source: | Dyes & Pigments. Mar2019, Vol. 162, p863-871. 9p. |
| Subjects: | Phenyl group, Organic light emitting diodes, Electroluminescent devices, Optoelectronic devices, Quantum efficiency |
| Abstract: | Abstract By introduction of trifluoromethyl and phenyl groups to 2-(2-thienyl)pyridine (thp), four new phosphorescent bis-cyclometalated iridium(III) complexes, (thp) 2 Ir(tpip), (cf 3 thp) 2 Ir(tpip), (cf 3 btp) 2 Ir(tpip) and (3-cf 3 btp) 2 Ir(tpip) (cf 3 thp = 2-(thiophen-2-yl)-4-(trifluoromethyl)pyridine, cf 3 btp = 2-(benzo[ b ]thiophen-2-yl)-4- (trifluoromethyl)pyridine, 3-cf 3 btp = 2-(benzo[ b ]thiophen-3-yl)-4-(trifluoromethyl)pyridine, tpip = tetraphenylimidodiphosphinate), were synthesized and fully characterized. The density functional theory and time-dependent DFT calculations show that the frontier orbitals are mainly localized in the Ir(III) ion and the cyclometalated ligands. Thus, the photophysical properties were dominated by the cyclometalated C∧N ligand, attributed to 3MLCT and 3ILCT transition. These Ir(III) complexes emit in the yellow-to-deep red region with photoluminescence quantum yields in the range 40.5–86.4% in CH 2 Cl 2 solutions at 298 K. The organic light-emitting diodes (OLEDs) using (thp) 2 Ir(tpip), (cf 3 thp) 2 Ir(tpip) and (cf 3 btp) 2 Ir(tpip) as yellow, orange and deep red emitters display good electroluminescent performance with low efficiency roll-off. Notably, the device based on (cf 3 thp) 2 Ir(tpip) possesses very high EL efficiencies with the maximum luminance efficiency and external quantum efficiency (EQE) of 53.9 cd A−1 and 17.9%, respectively. Furthermore, the EQE for this complex could be still retained as 15.4% at a luminance of 1000 cd m−2. Graphical abstract Image 1 Highlights • Four new phosphorescent iridium(III) complexes based on thienylpyridine derivatives were synthesized. • These iridium(III) complexes emit in the yellow-to-deep red region with photoluminescence quantum yields of 40.5–86.4%. • The yellow-to-deep red OLEDs have good performance with low efficiency roll-off. • The best device showed an EQE max of 17.9%, and the EQE remained as 15.4% at a luminance of 1000 cd m−2. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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