Cyclometalated Ir(III) Complexes for High-Efficiency Solution-Processable Blue PhOLEDs

Kozhevnikov, Valery N.; Zheng, Yonghao; Clough, Matthew T.; Al-Attar, Hameed A.; Griffiths, Gareth C.; Abdullah, Khalid A.; Raišys, Steponas; Jankus, Vygintas; Bryce, Martin R.; Monkman, Andrew P.

doi:10.1021/cm4010773

Cited by 111 publications

(129 citation statements)

References 36 publications

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“…Particularly, Ir(BDFPPya) 3 with the most fluorine atoms shows the lowest T d . It means that fluorination has a negative influence on the thermal stability, which agrees well with the conclusion of others [30,42].…”

Section: Thermal Analysissupporting

confidence: 91%

“…The PLQYs of these iridium complexes were determined to be 0.29, 0.44, and 0.84 for Ir(BPPya) 3 , Ir(BFPPya) 3 , and Ir(BDFPPya) 3 , respectively, measured in degassed DCM solution using Ir(ppy) 3 [29][30][31] as the calibration standard. Because the replacement of C-H bonds by C-F bonds lowers the vibrational frequency and hence reducing the nonradiative decay process and improving the PL efficiency [17,32,33], the PLQY of the complexes increases with the number of fluorine atoms.…”

Section: Photophysics and Electrochemical Propertiesmentioning

confidence: 99%

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Influences of fluorination on homoleptic iridium complexes with C∧N=N type ligand to material properties, ligand orientation and OLED performances

et al. 2014

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Two new iridium complexes with C^N=N type ligand (i.e., Ir(BFPPya) 3 {tris[3,6-bis(4-fluorophenyl)pyridazine]iridium(III)} and Ir(BDFPPya) 3 {tris[3,6-bis (2,4-di-fluorophenyl)pyridazine]iridium(III)}) attaching with fluorine atoms, were synthesized and the effects of fluorination on the material properties and device performance were investigated. Compared with our previously reported fluorine-free analogue material, that is Ir(BPPya) 3 {tris[3,6-bis(phenyl)pyridazine]iridium(III)}, blue shifts in the emission spectra as well as in the long wavelength region of the absorptions were observed. The photoluminescence quantum yield (PLQY) (0.44 and 0.84 vs 0.29), phosphoresces lifetime (0.88 and 1.31 vs 0.66 s), and oxidation potential (1.10 and 1.37 vs 0.95 V) increased obviously after fluorinating the ligand. In contrast, the thermal stability of the iridium complexes decreased slightly (Td: 435 and 402 vs 440 °C). In the density functional theory (DFT) calculations, by comparing the steric shape of the three ligands within one optimized molecule, orientational differences among the complexes were observed. In OLED device studies, bluish green electroluminescence with peak emission of 500 nm, using the electron-transporting host of TPBI [2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole)] and the most fluorinated dopant of Ir(BDFPPya) 3 , was achieved with maximum efficiency of 20.3 cd/A. On one hand this efficiency is not satisfactory considering a high PLQY of 0.84. On the other hand with the similar device structure, that the (HOMO-LUMO)s of all the dopants are wrapped within that of the host TPBI, and all the triplet energies of the dopants are smaller than that of the host TPBI, it is abnormal that the ordering of device efficiencies is contradictory to that of PLQY. Assisting with the phosphorescent spectrum of TPBI and the absorption spectra of the dopant, the contradiction was interpreted reasonably.

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Section: Thermal Analysissupporting

confidence: 91%

Section: Photophysics and Electrochemical Propertiesmentioning

confidence: 99%

Influences of fluorination on homoleptic iridium complexes with C∧N=N type ligand to material properties, ligand orientation and OLED performances

et al. 2014

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“…The mesppy and dFmesppy C^N ligands were each prepared in high yield via Suzuki-Miyaura 11 palladium-catalysed cross-coupling reactions. The bulky mesityl substituent was incorporated at the 4-position of the pyridine ring of ppy and dFppy C^N ligands as mesityl substitution had been previously shown by Bryce and co-workers 12 15 The qpy ligand was prepared in low yield following an oxidative Pd-catalyzed coupling reaction of 4,4'-bipyridine. 16 Complexes 1 and 2 were isolated through cleavage of D1 and D2 with qpy, whereas complex 3 was prepared through cleavage of D1 with dtbubpy.…”

Section: Synthesismentioning

confidence: 99%

Exploring the self-assembly and energy transfer of dynamic supramolecular iridium-porphyrin systems

et al. 2016

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“…94 Most of the parameters of 4-based OLEDs are significantly higher when compared to devices fabricated from asymmetric extended carbazoles, but this observation is countered with deeper/purer blue emission seen for the latter. 39,41 A quite similar bright blue emission was observed for OLEDs based on trialkylsilylanthracene yet with much lower luminosity of 107 cd/m 2 at 10 V. 91 The sky-blue OLEDs designed from benzo[k]fluoranthene 90 are matching ours suggesting a great potential in application of the more extended fused polyaromatics.…”

Section: Optical and Photophysical Propertiesmentioning

confidence: 99%

Highly Luminous Sky-Blue Organic Light-Emitting Diodes Based on the Bis[(1,2)(5,6)]indoloanthracene Emissive Layer

et al. 2016

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An in-depth analysis of the electro-optical and light emissive properties was carried out with a new fused heteroacene, the bis [(1,2)(5,6)] indoloanthracene. The compound was synthesized in a straightforward bidirectional manner from 1,4-dibromo-2,5-diodobenzene utilizing a reaction cascade of isomerisation and cyclisation sequences. Bis-[(1,2)(5,6)] indoloanthracene exhibits bright luminescence with high quantum yield in solution as well as in the solid state. By using this novel semiconductor as active layer, an efficient OLED has been fabricated for which its emission pattern resembles at least two emitters in a single emissive region originated from the same molecule. One has its origin from the single molecule and is similar to the luminescence spectra in solution, whereas the other functions through the formation of aggregates being similar with the emission pattern found with crystals of bis-[(1,2)(5,6)]indoloanthracene. As a result bright sky-blue OLEDs with very high luminance exceeding 10000 cd/m 2 were obtained. Such color pattern and performance has not previously been observed with low molecular weight, electron-rich fused polycyclic aromatic compounds and indicate a promising new class of materials for development.

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Cyclometalated Ir(III) Complexes for High-Efficiency Solution-Processable Blue PhOLEDs

Cited by 111 publications

References 36 publications

Influences of fluorination on homoleptic iridium complexes with C∧N=N type ligand to material properties, ligand orientation and OLED performances

Influences of fluorination on homoleptic iridium complexes with C∧N=N type ligand to material properties, ligand orientation and OLED performances

Exploring the self-assembly and energy transfer of dynamic supramolecular iridium-porphyrin systems

Highly Luminous Sky-Blue Organic Light-Emitting Diodes Based on the Bis[(1,2)(5,6)]indoloanthracene Emissive Layer

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