Novel bluish green benzimidazole-based iridium(<scp>iii</scp>) complexes for highly efficient phosphorescent organic light-emitting diodes

Zhao, Jinhui; Hu, Yong‐Xu; Yan, Dong; Xia, Xue; Chi, Haijun; Xiao, Guoyong; Li, Xiao; Zhang, Dongyu

doi:10.1039/c6nj03634a

Cited by 21 publications

(17 citation statements)

References 44 publications

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“…The small IP values can be associated with a favored hole injection from the anode into the luminescent material, while large EA values could be indicating an easy injection of electrons from the cathode into the iTMC . These parameters are defined according to the following equations:

italicIP = E_{N - 1} - E_{N}

italicEA = E_{N} - E_{N + 1}

where E N , E N +1 , and E N −1 , corresponds to the total energies of the molecular system in its fundamental state and with one more electron and one less electron, respectively …”

Section: Resultsmentioning

confidence: 99%

“…The reorganization energies can be obtained as follow:

λ_{hole} = italicIP - italicHEP

λ_{electron} = italicEA - italicEEP

where HEP and EEP correspond to the hole and electron extraction potentials, respectively. These potentials are calculated as the vertical energy difference between the relaxed cationic (anionic) molecule and the neutral molecule at the cationic (anionic) geometry …”

Section: Resultsmentioning

confidence: 99%

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Electron‐donor substituents on the dppz‐based ligands to control luminescence from dark to bright emissive state in Ir(III) complexes

Dreyse

Santander-Nelli

Zamorano

et al. 2020

Int J of Quantum Chemistry

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Dppz-based Ir(III) complexes show a competition between dark and bright excited states. Paulina Dreyse and colleagues in e26167 used DFT/TD-DFT to determine geometrical and photophysical properties, and the possible applicability of these systems as new luminescent materials in Light Emitting Electrochemical Cells (LECs). The study found an improved radiative decay (bright) in presence of electron-donor substituents.

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italicIP = E_{N - 1} - E_{N}

italicEA = E_{N} - E_{N + 1}

where E N , E N +1 , and E N −1 , corresponds to the total energies of the molecular system in its fundamental state and with one more electron and one less electron, respectively …”

Section: Resultsmentioning

confidence: 99%

“…The reorganization energies can be obtained as follow:

λ_{hole} = italicIP - italicHEP

λ_{electron} = italicEA - italicEEP

Section: Resultsmentioning

confidence: 99%

Electron‐donor substituents on the dppz‐based ligands to control luminescence from dark to bright emissive state in Ir(III) complexes

Dreyse

Santander-Nelli

Zamorano

et al. 2020

Int J of Quantum Chemistry

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“…The Δ HL of C2 is increased with respect to C1 by the trifluoromethyl substitution into the ancillary ligand. In this regard, the gap increasing in neutral and cationic Ir(III) complexes has been reached by the use of electron‐withdrawing groups in the C^N ligands, which stabilize the HOMO level through the outflow of electron density of the metal by inductive effects (favoring also the blue‐shifting of the emission wavelengths). Inductive effects are responsible for σ‐depletion by acceptor substituents, leading to the orbital stabilization by decreasing the repulsive Coulombic interactions between π and σ electrons in the aromatic moieties.…”

Section: Resultsmentioning

confidence: 99%

“…The reorganization energies of holes and electron are obtained as: λ hole =IP‐HEP and λ electron =EA‐EEP. HEP (EEP) is the hole (electron) extraction potential and obtained as the vertical energy difference between the relaxed state with one electron less (more) and the ground state but at the one electron less (more) geometry …”

Section: Resultsmentioning

confidence: 99%

“…Otherwise, the electron transfer rate is mainly favored in systems C1 , C3 and C6 (λ hole >λ electron ); while the hole transfer rate is mainly favored in the semiconductors C7‐C10 (λ hole <λ electron ). Furthermore, it was found that the Δλ values of the anionic complexes are lower compared to those of cationic Ir(III) complexes; in other words, the anionic complexes show a better balance between hole‐electron transfer than cationic complexes.…”

Section: Resultsmentioning

confidence: 99%

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Insights into the luminescent properties of anionic cyclometalated iridium(III) complexes with ligands derived from natural products

Cortés‐Arriagada

Dreyse

Salas

et al. 2018

Int J of Quantum Chemistry

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In the search of remarkable anionic electroluminescent semiconductors to be applied in energy conversion devices such as Light Emitting Electrochemical Cells, we report the electronic, photophysical, and charge injection/transfer properties of a series of cyclometalated iridium(III) complexes through a DFT/TD-DFT procedure. The proposed semiconductors involve bidentated ligands based on natural products (salicylic acid and boldine), and phenylpyridine and phenylpyrazole as the cyclometalating units. The proposed compounds emit in the range of 446 to 571 nm, where the boldine based compounds have red-shifted emissions compared to their analogs with salicylic acid. Blue phosphors were obtained by the use of phenylpyrazole units; however, the ligand field is weak in these cases compared to the ligand field exerted by the phenylpyridine ligands. The latter allows the accessibility to the radiationless states for emitters below 495 nm as a result of the increased stability of the metal centered excited states; consequently, the luminescent quantum yield could be decreased. Conversely, the semiconductors with phenylpyridine units show a restricted accessibility to radiationless processes, which could result in emitters with a high luminescent quantum yield and low non-radiative constants. Finally, the proposed anionic semiconductors show a better balance between hole/electron transfer rate compared to related cationic Ir (III) complexes; while, the easier hole-electron injection is favored for semiconductors with salicylic acid and phenylpyridine units.anionic semiconductors, iridium complexes, LECs, luminescence, TD-DFTThe improvement of the lighting technologies is a challenge to reduce the consumption of electrical energy. Solid-state lighting (SSL) systems comprise LED (Light Emitting Diode), OLED (Organic Light Emitting Diode), and LEC (Light Emitting Electrochemical Cell) devices. [1,2] In particular, LECs consist of a layer of an ionic transition metal complex (iTMC) with luminescent properties, which is sandwiched between two electrodes; a cathode that consists of a metal layer, and a transparent conductive film that acts as the anode. [3][4][5] In addition, LECs require less stringent packaging procedures compared to OLEDs since the iTMC layers are processed from a solution, and also because the air-sensitive electron injection layers are not necessary. [3][4][5] The cationic Ir(III) cyclometalated complexes of general formula [Ir(C^N) 2 (N^N)] 1 (C^N: cyclometalating ligand and N^N: ancillary ligand) have been widely used as semiconductor iTMCs, due to their remarkable photophysical properties such as i) high ligand-field splitting energy; [6,7] ii) the strong spin-orbit coupling (SOC) exerted by Ir; [7,8] iii) and wider color tunability through chemical functionalization and its effects onto the energy of frontier molecular orbitals. [1,9] Despite the wide implementation of cationic Ir(III) complexes, anionic complexes have also emerged as semiconductors for use in LEC devices. [10][11][12] In this regard, t...

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Organic and Organometallic Fluorinated Materials for Electronics and Optoelectronics: A Survey on Recent Research

et al. 2018

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Conjugated organic polymers, small molecules, and transition metal organometallic complexes are used as active semiconducting materials in electronic and optoelectronic devices including organic solar cells (OSCs), organic field effect transistors (OFETS), organic light emitting diodes (OLEDs). While some of these technologies are mature and already available on the market, research is still very active in academic and industrial laboratories to gain better performances. Major drawbacks which still limit large industrial production of some of these devices are not only the non‐optimized performances, but also stability issues and cost. In fact, wide applicability of organic electronic technology largely relies on the development of efficient, durable and cost‐effective materials. Properties of molecular and polymeric semiconductors can be properly engineered and finely tuned by the design of the conjugated molecular structure and the selective introduction of various functional groups as substituents. Selective functionalization of the conjugated backbone with fluorine atoms and fluorinated substituents has been largely demonstrated to be an effective structural modification not only for tuning optoelectronic properties, but also to affect solid state organization and to improve stability. This review covers the most important classes of materials (conjugated polymers, small molecules, and organometallic complexes) reporting for each of these classes the applications in OSCs, OFETs, and OLEDs and highlighting the role of fluorine functionalization on the properties. The literature shows intriguing results that can be achieved by fluorine functionalization, and it also points out that this research field is still promising for future progress.

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Novel bluish green benzimidazole-based iridium(iii) complexes for highly efficient phosphorescent organic light-emitting diodes

Abstract: Fluorinated benzimidazole-based Ir(iii) complexes were developed to regulate the emitting color and improve the luminous efficiency of Ir(iii) phosphors.

Cited by 21 publications

References 44 publications

Electron‐donor substituents on the dppz‐based ligands to control luminescence from dark to bright emissive state in Ir(III) complexes

Electron‐donor substituents on the dppz‐based ligands to control luminescence from dark to bright emissive state in Ir(III) complexes

Insights into the luminescent properties of anionic cyclometalated iridium(III) complexes with ligands derived from natural products

Organic and Organometallic Fluorinated Materials for Electronics and Optoelectronics: A Survey on Recent Research

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