Theoretical study on a series of iridium complexes with low efficiency roll-off property

Song, Ming‐Xing; Wang, Guofeng; Wang, Jin; Wang, Yuhai; Bai, Fu‐Quan; Qin, Zheng‐Kun

doi:10.1016/j.saa.2014.06.088

Cited by 24 publications

(8 citation statements)

References 44 publications

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“…Notably, cyclometalated iridium complexes are the most preferred phOLEDs due to their chemical stability, high phosphorescent efficiency, and attainable red to blue color emitting and have been extensively investigated in both experimental and theoretical fields. − A widely known example is the green-emitting complex fac -Ir(ppy) 3 ( 1 ; ppy = 2-phenylpyridine), which was reported by Watts and co-workers in 1991 . From then on, vastly improved iridium complexes sprang up mainly based on the tris-cyclometalated fac -Ir(ppy) 3 .…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Investigation into Luminescent Properties of Ir(III) Complexes: An Integrated Computational Study of Radiative and Nonradiative Decay Processes

et al. 2018

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A comprehensive and concrete exploration into the deactivation mechanisms of luminescent materials is imperative, with the improvement of simulating and computing technology. In this study, an integrated calculation scheme is employed on five Ir(III) complexes for thorough investigation of their photophysical properties, including radiative ( k) and nonradiative ( k) decay rates. As a most famous Ir(III) complex with superior quantum efficiency, fac-Ir(ppy) herein serves as a reference relative to the other four β-diketonate complexes. Both temperature-independent and temperature-dependent k are taken into account quantitatively for the first time, to unearth the role of different ancillary ligands in the determination of luminescent properties. Since the validated calculations of k for the five complexes are of the same order of magnitude, the nonemissive peculiarity of 4 is caused by large k. The newly designed compound 5, which simply has two more -CH groups than 4 in the ancillary ligand, further manifests that the reason for large k in molecule 4 should be attributed to the ligand resonance caused by great π conjugation.

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Section: Introductionmentioning

confidence: 99%

Comprehensive Investigation into Luminescent Properties of Ir(III) Complexes: An Integrated Computational Study of Radiative and Nonradiative Decay Processes

et al. 2018

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“…It is noteworthy that cyclometalated Ir(III) complexes are frequently considered to be the most promising phOLEDs due to their excellent phosphorescent quantum efficiency, thermal and electrochemical stability, and short lifetimes of the triplet excited state, as well as the tunability in red (700 nm or 1.77 eV) to blue (435.8 nm or 2.85 eV) color transformation, and have been extensively investigated in both experimental − and theoretical domains. − However, it is still a genuine challenge to develop blue-emitting phosphorescent complexes, since the IQE drops severely when the emission turns to blue. ,, The larger energy gap required by blue-emitting Ir(III) complexes reduces the quantum yield mainly due to a significant increase in nonradiative decay rates. , A seminal sky blue phosphorescent cyclometalated Ir(III) complex is the well-known iridium(III) bis[(4,6-difluorophenyl)-pyridinato- N , C 2′ ] picolinate (FIrpic), which has been demonstrated to be an excellent phosphorescent material in phOLEDs . The introduction of electron-withdrawing fluorine atoms on the ppy (2-phenylpyrdine) ligands, resulting in an enhancement of triplet exciton energy, renders a blue shift of phosphorescence .…”

Section: Introductionmentioning

confidence: 99%

Strategies on Cyclometalating Ligand Substitution of Several Ir(III) Complexes: Theoretical Investigation of Different Molecular Behaviors

Wang

Zhang

et al. 2018

Organometallics

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A series of Ir(III) light-emitting materials, namely Ir(R-dfpypy)2pic (R-dfpypy = 2′,6′-difluoro-4-R-2,3′-bipyridine, pic = picolinate), where R = −H (1), −CN (2), −OMe (3), −NMe2 (4), −N(CF3) 2 (5), is evaluated through a comprehensive theoretical approach in this study. It has been observed in experiments that different kinds of substituent groups on the dfpypy cyclometalating ligands brought about considerable photophysical discrepancies. From a theoretical aspect, these Ir(III) complexes have no obvious differences in the calculation of radiative decay rates (k r), which is consistent with experimental results. A convolution method utilized in computation of the nonradiative decay rate (k nr) reveals that complex 4 is nonemissive due to its 1 or 2 orders of magnitude larger k nr in comparison to the corresponding k r. Further decomposition of vibration modes that contribute the most to reorganization energies in low- and high-frequency regions into internal coordinates indicates that it is the intense oscillation of bulky substituent groups in complex 4 that leads to its faster k nr. On the basis of our corroborated theoretical approach, the issue of whether the character or the bulk of the substituent groups influences the quantum efficiency of these similar Ir(III) light-emitting materials is determined. Therefore, complex 5, which replaces hydrogen with fluorine atoms in the substituent groups of complex 4, was investigated further through vibrational analysis. In comparison with the first four compounds, complex 5 has a comparable calculated k r value and has an even larger k nr than complex 4. Although both compounds 2 and 5 have electron-withdrawing substituent groups, the chemical properties of substituent groups cannot absolutely determine the nonradiative decay process. Moreover, the metal-centered (3MC) triplet excited states and other relative temperature-dependent nonradiative photodeactivation pathways have also been simulated for all complexes.

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“…6 At the moment, most computationally demanding studies of sizeable TM complexes applied in catalysis are performed with DFT in combination with the B3LYP functional and its extension in the time-domain in the linear response formulation (TDDFT). [7][8][9][10][11][12][13][14][15] Besides efficiency it is the absence of system-dependent parameters that need to be determined first (such as the active space in multi-reference methods), which makes (TD)DFT attractive. The power of the DFT method to reproduce different electronic ground state properties even for rather large systems is well documented.…”

Section: Introductionmentioning

confidence: 99%

Tuning Range-Separated Density Functional Theory for Photocatalytic Water Splitting Systems

Bokarev

Grell

Kühn

2015

J. Chem. Theory Comput.

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We discuss the system-specific optimization of long-range separated density functional theory (DFT) for the prediction of electronic properties relevant for a photocatalytic cycle based on an Ir(III) photosensitizer (IrPS). Special attention is paid to the charge-transfer properties, which are of key importance for the photoexcitation dynamics, but and cannot be correctly described by means of conventional DFT. The optimization of the rangeseparation parameter using the ∆SCF method is discussed for IrPS including its derivatives and complexes with electron donors and acceptors used in photocatalytic hydrogen production. Particular attention is paid to the problems arising for a description of medium effects by means of a polarizable continuum model.

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Theoretical study on a series of iridium complexes with low efficiency roll-off property

Cited by 24 publications

References 44 publications

Comprehensive Investigation into Luminescent Properties of Ir(III) Complexes: An Integrated Computational Study of Radiative and Nonradiative Decay Processes

Comprehensive Investigation into Luminescent Properties of Ir(III) Complexes: An Integrated Computational Study of Radiative and Nonradiative Decay Processes

Strategies on Cyclometalating Ligand Substitution of Several Ir(III) Complexes: Theoretical Investigation of Different Molecular Behaviors

Tuning Range-Separated Density Functional Theory for Photocatalytic Water Splitting Systems

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