A theoretical study on the injection, transport, absorption and phosphorescence properties of heteroleptic iridium(iii) complexes with different ancillary ligands

Xiaohong Shang, Ning Wan, Deming Han, Gang Zhang

Research output: Contribution to journalArticle

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Abstract

We have reported a theoretical analysis of a series of heteroleptic iridium(iii) complexes (mpmi)2Ir(fppi) [mpmi = 1-(4-tolyl)-3-methyl- imidazole, fppi = 4-fluoro-2-(pyrrol-2-yl)-pyridine] (1a), (mpmi) 2Ir(dfpi) [dfpi = 4-fluoro-2-(3-fluoro-pyrrol-2-yl)-pyridine] (1b), (mpmi)2Ir(tfpi) [tfpi = 2-(pyrrol-2-yl)-4-trifluoromethyl-pyridine] (1c), (mpmi)2Ir(priq) [priq = 1-(pyrrol-2-yl)isoquinoline] (2a), (mpmi)2Ir(isql) [isql = 1-(indol-2-yl)-isoquinoline] (2b), and (mpmi)2Ir(biql) [biql = 1-(benzoimidazol-2-yl)-isoquinoline] (2c) by using the density functional theory (DFT) method to investigate their electronic structures, photophysical properties, and the phosphorescent efficiency mechanism. The results reveal that the nature of the ancillary ligands can affect the electron density distributions and energies of frontier molecular orbitals, resulting in changes of charge transfer performances and emission color. It is found that the studied complex 1c with the -CF3 substituent at the pyridine moiety results in the lower HOMO-LUMO energy gap and LUMO energy level, which will lead to a rich electron injection ability compared with that of 1a. For each complex studied (except 2b), the hole-transporting performance is better than the electron-transporting performance. In addition, for complexes 2a and 2b, the differences between reorganization energies for hole transport (λih) and reorganization energies for electron transport (λie) are relatively smaller, indicating that the hole and electron transfer balance could be achieved more easily in the emitting layer. It is believed that the largest metal to ligand charge transfer (MLCT) character, the higher μS1 and ET1 values, as well as the smallest ΔES 1-T1 value could result in higher phosphorescent quantum efficiency for 1b than those of other complexes.

Original languageEnglish (US)
Pages (from-to)574-582
Number of pages9
JournalPhotochemical and Photobiological Sciences
Volume13
Issue number3
DOIs
StatePublished - Jan 1 2014

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Iridium
Phosphorescence
phosphorescence
iridium
pyridines
transport properties
injection
Ligands
ligands
Charge transfer
charge transfer
Electron injection
Electronic density of states
electrons
Electrons
Molecular orbitals
Quantum efficiency
imidazoles
Electron energy levels
Electronic structure

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

Cite this

@article{57304f419f2041feaf6aa37fd299be63,
title = "A theoretical study on the injection, transport, absorption and phosphorescence properties of heteroleptic iridium(iii) complexes with different ancillary ligands",
abstract = "We have reported a theoretical analysis of a series of heteroleptic iridium(iii) complexes (mpmi)2Ir(fppi) [mpmi = 1-(4-tolyl)-3-methyl- imidazole, fppi = 4-fluoro-2-(pyrrol-2-yl)-pyridine] (1a), (mpmi) 2Ir(dfpi) [dfpi = 4-fluoro-2-(3-fluoro-pyrrol-2-yl)-pyridine] (1b), (mpmi)2Ir(tfpi) [tfpi = 2-(pyrrol-2-yl)-4-trifluoromethyl-pyridine] (1c), (mpmi)2Ir(priq) [priq = 1-(pyrrol-2-yl)isoquinoline] (2a), (mpmi)2Ir(isql) [isql = 1-(indol-2-yl)-isoquinoline] (2b), and (mpmi)2Ir(biql) [biql = 1-(benzoimidazol-2-yl)-isoquinoline] (2c) by using the density functional theory (DFT) method to investigate their electronic structures, photophysical properties, and the phosphorescent efficiency mechanism. The results reveal that the nature of the ancillary ligands can affect the electron density distributions and energies of frontier molecular orbitals, resulting in changes of charge transfer performances and emission color. It is found that the studied complex 1c with the -CF3 substituent at the pyridine moiety results in the lower HOMO-LUMO energy gap and LUMO energy level, which will lead to a rich electron injection ability compared with that of 1a. For each complex studied (except 2b), the hole-transporting performance is better than the electron-transporting performance. In addition, for complexes 2a and 2b, the differences between reorganization energies for hole transport (λih) and reorganization energies for electron transport (λie) are relatively smaller, indicating that the hole and electron transfer balance could be achieved more easily in the emitting layer. It is believed that the largest metal to ligand charge transfer (MLCT) character, the higher μS1 and ET1 values, as well as the smallest ΔES 1-T1 value could result in higher phosphorescent quantum efficiency for 1b than those of other complexes.",
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A theoretical study on the injection, transport, absorption and phosphorescence properties of heteroleptic iridium(iii) complexes with different ancillary ligands. / Shang, Xiaohong; Wan, Ning; Han, Deming; Zhang, Gang.

In: Photochemical and Photobiological Sciences, Vol. 13, No. 3, 01.01.2014, p. 574-582.

Research output: Contribution to journalArticle

TY - JOUR

T1 - A theoretical study on the injection, transport, absorption and phosphorescence properties of heteroleptic iridium(iii) complexes with different ancillary ligands

AU - Shang, Xiaohong

AU - Wan, Ning

AU - Han, Deming

AU - Zhang, Gang

PY - 2014/1/1

Y1 - 2014/1/1

N2 - We have reported a theoretical analysis of a series of heteroleptic iridium(iii) complexes (mpmi)2Ir(fppi) [mpmi = 1-(4-tolyl)-3-methyl- imidazole, fppi = 4-fluoro-2-(pyrrol-2-yl)-pyridine] (1a), (mpmi) 2Ir(dfpi) [dfpi = 4-fluoro-2-(3-fluoro-pyrrol-2-yl)-pyridine] (1b), (mpmi)2Ir(tfpi) [tfpi = 2-(pyrrol-2-yl)-4-trifluoromethyl-pyridine] (1c), (mpmi)2Ir(priq) [priq = 1-(pyrrol-2-yl)isoquinoline] (2a), (mpmi)2Ir(isql) [isql = 1-(indol-2-yl)-isoquinoline] (2b), and (mpmi)2Ir(biql) [biql = 1-(benzoimidazol-2-yl)-isoquinoline] (2c) by using the density functional theory (DFT) method to investigate their electronic structures, photophysical properties, and the phosphorescent efficiency mechanism. The results reveal that the nature of the ancillary ligands can affect the electron density distributions and energies of frontier molecular orbitals, resulting in changes of charge transfer performances and emission color. It is found that the studied complex 1c with the -CF3 substituent at the pyridine moiety results in the lower HOMO-LUMO energy gap and LUMO energy level, which will lead to a rich electron injection ability compared with that of 1a. For each complex studied (except 2b), the hole-transporting performance is better than the electron-transporting performance. In addition, for complexes 2a and 2b, the differences between reorganization energies for hole transport (λih) and reorganization energies for electron transport (λie) are relatively smaller, indicating that the hole and electron transfer balance could be achieved more easily in the emitting layer. It is believed that the largest metal to ligand charge transfer (MLCT) character, the higher μS1 and ET1 values, as well as the smallest ΔES 1-T1 value could result in higher phosphorescent quantum efficiency for 1b than those of other complexes.

AB - We have reported a theoretical analysis of a series of heteroleptic iridium(iii) complexes (mpmi)2Ir(fppi) [mpmi = 1-(4-tolyl)-3-methyl- imidazole, fppi = 4-fluoro-2-(pyrrol-2-yl)-pyridine] (1a), (mpmi) 2Ir(dfpi) [dfpi = 4-fluoro-2-(3-fluoro-pyrrol-2-yl)-pyridine] (1b), (mpmi)2Ir(tfpi) [tfpi = 2-(pyrrol-2-yl)-4-trifluoromethyl-pyridine] (1c), (mpmi)2Ir(priq) [priq = 1-(pyrrol-2-yl)isoquinoline] (2a), (mpmi)2Ir(isql) [isql = 1-(indol-2-yl)-isoquinoline] (2b), and (mpmi)2Ir(biql) [biql = 1-(benzoimidazol-2-yl)-isoquinoline] (2c) by using the density functional theory (DFT) method to investigate their electronic structures, photophysical properties, and the phosphorescent efficiency mechanism. The results reveal that the nature of the ancillary ligands can affect the electron density distributions and energies of frontier molecular orbitals, resulting in changes of charge transfer performances and emission color. It is found that the studied complex 1c with the -CF3 substituent at the pyridine moiety results in the lower HOMO-LUMO energy gap and LUMO energy level, which will lead to a rich electron injection ability compared with that of 1a. For each complex studied (except 2b), the hole-transporting performance is better than the electron-transporting performance. In addition, for complexes 2a and 2b, the differences between reorganization energies for hole transport (λih) and reorganization energies for electron transport (λie) are relatively smaller, indicating that the hole and electron transfer balance could be achieved more easily in the emitting layer. It is believed that the largest metal to ligand charge transfer (MLCT) character, the higher μS1 and ET1 values, as well as the smallest ΔES 1-T1 value could result in higher phosphorescent quantum efficiency for 1b than those of other complexes.

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