Rational design and characterization of heteroleptic phosphorescent iridium(<scp>iii</scp>) complexes for highly efficient deep-blue OLEDs

Feng, Yansong; Zhuang, Xuming; Zhu, Dongxia; Liu, Yu; Wang, Yue; Bryce, Martin R.

doi:10.1039/c6tc04119a

Cited by 52 publications

(13 citation statements)

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“…[7] Similar high efficiencies, in the 15-20% range without outcoupling enhancement are not common, but have been observed for OLEDs based on other Ir(C^C) 3 and Ir(C^N) 3 phosphors. [7,13,20,26,[42][43][44][45][46][47][48][49]…”

Section: Electroluminescence Propertiesmentioning

confidence: 99%

Blue Emissive fac/mer‐Iridium (III) NHC Carbene Complexes and their Application in OLEDs

Idris

Kapper

Tadle

et al. 2021

Advanced Optical Materials

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transition metal complexes as phosphorescent emitters, making it possible to harvest both singlet and triplet excitons leading to 100% electroluminescence quantum efficiency. [2] Cyclometalated iridium(III) complexes have emerged as one of the most promising triplet emitters because of their versatile color tunability, chemical stability, good thermal properties, and high photoluminescent quantum yields (Φ PL ). [3][4][5][6][7] These phosphors often involve an octahedral Ir 3+ ion with bidentate ligands, C^N:, comprised of a covalently bonded aryl moiety and a datively bonded nitrogen group, such as pyridyl, to give a tris-cyclometalated complex, Ir(C^N:) 3 . While efficient OLEDs using red and green Ir-based phosphorescent emitters are commercially viable, [8][9][10] the stability of OLEDs using blue-emitting transition metal containing complexes are presently insufficient for practical applications. [11] Recently cyclometalated N-heterocyclic carbene (NHC)-Ir based chromophores, Ir(C^C:) 3 , have attracted attention due to their promising properties as blue emitters. [12][13][14][15][16][17][18][19] These C^C: based emitters have an aryl group as do C^N: ligands, but utilize a carbene in place of the nitrogen basic moiety. Our group reported one of the first blue-emitting Ir-carbene complexes for OLEDs, using N-phenyl, N-methyl-imidazol-2-yl (pmi) and N-phenyl, N-methyl-benzimidazol-2-yl (pmb) ligands. [16] Since then, several homoleptic [20][21][22][23] and heteroleptic [18] derivatives of these complexes have also been reported. These Ir(C^C:) 3 complexes have advantages over blue emissive Ir(C^N:) 3 complexes as they do not suffer from deactivation of the excited state via thermal population of triplet metal-centered ( 3 MC) states, which can severely diminish their Φ PL . Replacing the nitrogen basic moiety in the C^N: ligand with a strong field carbene ligand, largely mitigates this problem by destabilizing the 3 MC states, which makes them thermally inaccessible. Interestingly, it was found that even when the 3 MC states are thermally populated, the carbene iridium complexes were able to undergo reversible population of the radiative state leaving the Ir-carbene bond intact. [24] Since the Ir-N bond dissociation in the excited state has been shown to be problematic in Ir(C^N:) 3 complexes, [4] computational results have suggested that replacement with the stronger IrC carbene bond will result in a more robust emitter. [24,25] Further work on Ir(C^C:) 3 complexes led to the use of the electrophilic N-phenyl, N-methyl-pyridylimidazol-2-yl ligand The photophysical and electrochemical properties of N-heterocyclic carbene complexes of Iridium (III) (Ir(C^C:) 3 , where C^C: = N-phenyl,N-methylpyrazinoimidazol-2-yl (pmpz), N,N-di-p-tolyl-pyrazinoimidazol-2-yl (tpz)) are reported. Facial and meridional isomers of Ir(pmpz) 3 are prepared, but only the facial isomer can be isolated for Ir(tpz) 3 . The fac-Ir(pmpz) 3 and fac-Ir(tpz) 3 complexes have emission maxima at 465 nm in polystyrene, whereas the emission max...

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Section: Electroluminescence Propertiesmentioning

confidence: 99%

Blue Emissive fac/mer‐Iridium (III) NHC Carbene Complexes and their Application in OLEDs

Idris

Kapper

Tadle

et al. 2021

Advanced Optical Materials

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“…Correspondingly, there are hundreds of homoleptic tris‐cyclometalated Ir complexes Ir( C ^ N ) 3 ( C ^ N = cyclometalated ligand) based on the parent Ir(ppy) 3 structure (ppy = 2‐phenylpyridine) , . Heteroleptic Ir complexes ( C ^ N ) 2 Ir( LX ) incorporating ancillary ligands ( LXs ) such as acetylacetonate (acac), picolinate, triazolate and amidinate derivatives have also been widely developed, especially in the context of tuning the emission color . However, there is only very limited information on tris‐cyclometalated Ir complexes containing mixed C ^ N ligands, ( C ^ N 1 ) 2 Ir( C ^ N 2 ) as these species have only rarely been characterized , .…”

Section: Introductionmentioning

confidence: 99%

New Mixed‐C^{^}N Ligand Tris‐Cyclometalated Ir^III Complexes for Highly‐Efficient Green Organic Light‐Emitting Diodes with Low Efficiency Roll‐Off

Liang

Bai

et al. 2018

Eur J Inorg Chem

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This article reports new tris-cyclometalated Ir III complexes containing mixed-C^N ligands, (C^N 1 ) 2 Ir(C^N 2 ), which are a rarely explored class of complexes. Two mixed 2-phenylpyridine (ppy)/4-methyl-2,5-diphenylpyridine (mdp) complexes (ppy) 2 Ir(mdp) 3 and (ppy)Ir(mdp) 2 4 have been synthesized and their optoelectronic properties have been systematically characterized. Photoluminescence quantum yield values are 0.76-0.85; excited state lifetimes are 0.07-0.11 μs. Phosphorescent organic light emitting devices (PhOLEDs) based on these emissive complexes in a very simple device architecture reproducibly showed slightly higher external quantum efficiency (EQE) and power efficiency (PE) values compared with devices using the analogous conventional homoleptic Ir complexes [a]

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“…In this combination, the blue emitter helps to reduce the power consumption of the device as well to generate other colors. Highly conjugated fluorescent or phosphorescent molecular systems are currently used as deep blue emitters in OLEDs . However, an inherent problem with these blue emitters is their wide band gap causing poor charge injection, exciton instability and consequent poor device performance.…”

Section: Introductionmentioning

confidence: 99%

Multicomponent‐Reaction‐ (MCR‐) Assisted Synthesis of a Coumarin‐Based Deep Blue Emitter for OLEDs and Related Applications

Puthumana

Bahulayan

2018

ChemistrySelect

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The lighting and display solutions of the future are Organic Light Emitting Diodes (OLEDs). For the electron transportation, hole transportation and light emission, sequential layers of specially designed organic molecules and materials are used in OLEDs. The perfect blue-emitters showing CIE (Commission Internationale de l'Eclairage) coordinates with a y-component smaller than 0.1 are highly desired for OLED technology. Herein we report an efficient step economic protocol for the synthesis of a deep blue emitting fluorescent molecule named as "Ugi EML BLUE" (l ems 443 nm; C.I.E. X = 0.162, Y = 0.012; HOMO/ LUMO =-5.94 eV/-1.60 eV) suitable for the emissive layers (EML) of OLEDs and related applications.[a] S.

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Rational design and characterization of heteroleptic phosphorescent iridium(iii) complexes for highly efficient deep-blue OLEDs

Cited by 52 publications

References 50 publications

Blue Emissive fac/mer‐Iridium (III) NHC Carbene Complexes and their Application in OLEDs

Blue Emissive fac/mer‐Iridium (III) NHC Carbene Complexes and their Application in OLEDs

New Mixed‐C^{^}N Ligand Tris‐Cyclometalated Ir^III Complexes for Highly‐Efficient Green Organic Light‐Emitting Diodes with Low Efficiency Roll‐Off

Multicomponent‐Reaction‐ (MCR‐) Assisted Synthesis of a Coumarin‐Based Deep Blue Emitter for OLEDs and Related Applications

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Rational design and characterization of heteroleptic phosphorescent iridium(iii) complexes for highly efficient deep-blue OLEDs

Cited by 52 publications

References 50 publications

Blue Emissive fac/mer‐Iridium (III) NHC Carbene Complexes and their Application in OLEDs

Blue Emissive fac/mer‐Iridium (III) NHC Carbene Complexes and their Application in OLEDs

New Mixed‐C^N Ligand Tris‐Cyclometalated IrIII Complexes for Highly‐Efficient Green Organic Light‐Emitting Diodes with Low Efficiency Roll‐Off

Multicomponent‐Reaction‐ (MCR‐) Assisted Synthesis of a Coumarin‐Based Deep Blue Emitter for OLEDs and Related Applications

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Product

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New Mixed‐C^{^}N Ligand Tris‐Cyclometalated Ir^III Complexes for Highly‐Efficient Green Organic Light‐Emitting Diodes with Low Efficiency Roll‐Off