Efficient red phosphorescent Ir(<scp>iii</scp>) complexes based on rigid ligands with high external quantum efficiency and low efficiency roll-off

Liu, Sheng-Nan; Tong, Kai‐Ning; Zhao, Yue; Cheng, Jin-Feng; Fung, Man‐Keung; Fan, Jian

doi:10.1039/c9tc06940b

Cited by 12 publications

(12 citation statements)

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“…57 Population of the triplet state can often lead to significant nonradiative decay because the triplet state is more prone to vibrational deactivation to the ground state. 58 However, strong triplet-state emission has been observed in cases where the emitting ligand is sufficiently rigid as it coordinates to the heavy atom, leading to solid-state QYs as high as 25% and reported lifetimes of 0.0998 s. 34,59,60 This ligand rigidity is achieved in Bi-1 through supramolecular interactions. The strong π−π-stacking interactions between Hphen and PDC effectively sandwich Hphen and prevent movement perpendicular to the plane of those interactions.…”

Section: ■ Discussionmentioning

confidence: 99%

Harnessing Bismuth Coordination Chemistry to Achieve Bright, Long-Lived Organic Phosphorescence

et al. 2021

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A new bismuth(III)−organic compound, Hphen-[Bi 2 (HPDC) 2 (PDC) 2 (NO 3 )]•4H 2 O (Bi-1; PDC = 2,6-pyridinedicarboxylate and phen = 1,10-phenanthroline), was synthesized, and the structure was determined by single-crystal X-ray diffraction. The compound was found to display bright-bluegreen phosphorescence in the solid state under UV irradiation, with a luminescent lifetime of 1.776 ms at room temperature. The room temperature and low-temperature (77 K) emission spectra exhibited the vibronic structure characteristic of Hphen phosphorescence. Time-dependent density functional theory studies showed that the excitation pathway arises from an energy transfer from the dimeric structural unit to Hphen, with participation from a ninecoordinate Bi center. The triplet state of Hphen is believed to be stabilized via supramolecular interactions, which, when coupled with the heavy-atom effect induced by Bi, leads to the observed longlived luminescence. The compound displayed a solid-state quantum yield of over 27%. To the best of our knowledge, this is the first such compound to exhibit phenanthrolinium phosphorescence with such long-lived, room temperature lifetimes in the solid state. To further elucidate the energy-transfer mechanism, Ln 3+ (Ln = Eu, Tb, Sm) ions were successfully doped into the parent compound, and the resulting materials exhibited dual emission from Hphen and Ln, promoting tunability of the emission color.

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Section: ■ Discussionmentioning

confidence: 99%

Harnessing Bismuth Coordination Chemistry to Achieve Bright, Long-Lived Organic Phosphorescence

et al. 2021

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“…Transition metal complexes, such as iridium (Ir), [20][21][22][23][24][25] platinum (Pt) [26][27][28][29][30][31] and osmium (Os) [32][33][34][35] complexes, are a type of the most promising NIR-emitting materials. These complexes have been developed rapidly in recent decades as they can fully use the triplet exciton to realize high-efficiency emission with theoretically 100% internal quantum efficiency (IQE).…”

Section: Introductionmentioning

confidence: 99%

714 nm emission with 12.25% efficiency from iridium complexes with low iridium content by the strategy of rigid coordination core and amplifying shell

Wang

You

et al. 2022

J. Mater. Chem. C

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“…In addition, compared to a flexible or semirigid bidentate ligand, the use of a rigid bidentate ligand can give better efficiency similar to tridentate chromophoric ligands. 31 The flexible or semirigid ligands (bidentate as well as tridentate chromophoric ligands) were considered as weakly conjugating ligands and were utilized to make blue or deep blue emitters with high efficiency, whereas a rigid framework is believed to achieve the materials that emit beyond 600 nm. 46 Herein, we report two iridium complexes possessing naphthalene benzimidazole (NBI) based rigid C^N ligand (L 1 and L 2 ) and ancillary pyrazole ligand (PyPz CF3 , L 3 ).…”

Section: ■ Introductionmentioning

confidence: 99%

“…In this regard, phenyl-benzimidazole and its derivatives can be an alternative source for the construction of efficient iridium emitters. , Similar to the traditional method, the emission color of the emitter can be easily tuned by incorporating electron-donating/-withdrawing groups into the benzimidazole and phenylene units (Figure ). In particular, whereas green- and red-emitting OLEDs have been relatively well developed, − deep red and near-IR (NIR) emissive materials are still in their early developmental stage. − Recently, Pt(II)- and Os(II)-based emitters were used to develop NIR OLEDs with high efficiency and low efficiency roll-off. − The extension of an aromatic unit or the introduction of electron-withdrawing groups to the benzimidazole moiety will help in the stabilization of the lowest unoccupied molecular orbital (LUMO) level. Likewise, attaching electron-donating moieties to the naphthalene unit will assist in destabilizing the highest occupied molecular orbital (HOMO), both of which can help develop a new series of deep red/NIR phosphorescent materials.…”

Section: Introductionmentioning

confidence: 99%

“…Likewise, attaching electron-donating moieties to the naphthalene unit will assist in destabilizing the highest occupied molecular orbital (HOMO), both of which can help develop a new series of deep red/NIR phosphorescent materials. In addition, compared to a flexible or semirigid bidentate ligand, the use of a rigid bidentate ligand can give better efficiency similar to tridentate chromophoric ligands . The flexible or semirigid ligands (bidentate as well as tridentate chromophoric ligands) were considered as weakly conjugating ligands and were utilized to make blue or deep blue emitters with high efficiency, whereas a rigid framework is believed to achieve the materials that emit beyond 600 nm …”

Section: Introductionmentioning

confidence: 99%

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Naphthalene Benzimidazole Based Neutral Ir(III) Emitters for Deep Red Organic Light-Emitting Diodes

et al. 2020

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Rigid naphthalene benzimidazole (NBI) based ligands (L1 and L2) are synthesized and utilized to make deep red phosphorescent cyclometalated iridium(III) complexes ([Ir(NBI)2(PyPzCF3)] (1) and [Ir(DPANBI)2(PyPzCF3)] (2)). Complexes 1 and 2 are prepared from the reaction of L1/L2 with the aid of ancillary ligands (PyPzCF3 , 2-(3-(trifluoromethyl)-1H-pyrazol-5-yl)pyridine) in a two step method. The complexes are characterized by analytical and spectroscopic methods, as well as X-ray diffraction for 1. These complexes show a strong emission in the range of 635–700 nm that extends up to the near-infrared region (800 nm). The introduction of the diphenylamino (DPA) donor group on the naphthalene unit leads to a further red-shift in the emission. The complexes exhibit radiative quantum efficiency (ΦPL) of 0.27–0.29 in poly(methylmethacrylate) film and relatively short phosphorescence decay lifetimes (τ = 1.1–3.5 μs). The structural, electronic, and optical properties are investigated with the support of density functional theory (DFT) and time-dependent-DFT calculations. The calculation results indicate that the lowest-lying triplet (T1) excited state of 1 has a mixed metal-to-ligand charge transfer (3MLCT) and ligand-centered (3LC) character, while 2 shows a dominant 3LC character. Deep red-emitting organic light-emitting diodes fabricated using 1 as a dopant display a maximum external quantum efficiency of 10.9% with the CIE color coordinates of (0.690, 0.294), with an emission centered at 644 and 700 nm. Similarly, the emitter 2 also shows a maximum external quantum efficiency of 6.9% with emissions at 657 and 722 nm.

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Efficient red phosphorescent Ir(iii) complexes based on rigid ligands with high external quantum efficiency and low efficiency roll-off

Abstract: Two highly efficient red phosphorescent Ir(iii) complexes were prepared by the introduction of rigid cyclometalating ligands.

Cited by 12 publications

References 58 publications

Harnessing Bismuth Coordination Chemistry to Achieve Bright, Long-Lived Organic Phosphorescence

Harnessing Bismuth Coordination Chemistry to Achieve Bright, Long-Lived Organic Phosphorescence

714 nm emission with 12.25% efficiency from iridium complexes with low iridium content by the strategy of rigid coordination core and amplifying shell

Naphthalene Benzimidazole Based Neutral Ir(III) Emitters for Deep Red Organic Light-Emitting Diodes

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