Synthesis and characterization of cyclometalated Ir(III) complexes with pyrazolyl ancillary ligands

Li, Jian; Djurovich, Peter I.; Alleyne, Bert D.; Tsyba, Irina; Ho, Nam Nhat; Bau, Robert; Thompson, Mark E.

doi:10.1016/j.poly.2003.11.028

Cited by 141 publications

(111 citation statements)

References 77 publications

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“…[21] Therefore, the blue-shifting power of the ancillary ligand becomes the decisive structural factor for improving the blue color of FIrpic. [33] In fact, the blue-shifting power of anionic nitrogen-based heterocyclic rings as ancillary ligands has not been noted until very recently. [24,33,34] Here, we will demonstrate that the new tetrazolate-based ancillary ligand has a blue-shifting power comparable to that of the trifluoromethylsubstituted triazolate, yet still better than that of the known picolate of FIrpic.…”

Section: ±1mentioning

confidence: 99%

“…[33] In fact, the blue-shifting power of anionic nitrogen-based heterocyclic rings as ancillary ligands has not been noted until very recently. [24,33,34] Here, we will demonstrate that the new tetrazolate-based ancillary ligand has a blue-shifting power comparable to that of the trifluoromethylsubstituted triazolate, yet still better than that of the known picolate of FIrpic. Moreover, tetrazolate-based ancillary ligands have the added advantage of ease of synthetic variation over that of the trifluoromethyl-substituted triazolate (see Experimental section), and thus serve as our initial model material in the quest for blue-light-emitting phosphorescent OLEDs.…”

Section: ±1mentioning

confidence: 99%

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New Dopant and Host Materials for Blue‐Light‐Emitting Phosphorescent Organic Electroluminescent Devices

Yeh

Chen³

et al. 2005

Advanced Materials

685

232

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Organic triplet-state light-emitting materials (organic phosphorophores) have been one of the most important recent developments in the field of organic light-emitting diodes (OLEDs).[1±4] Organic electrophosphorescent materials provided one of the major breakthroughs in electroluminescence efficiency, which is usually limited to an external quantum efficiency (EQE) of around 5 % for devices based on singletstate fluorescent materials. Owing to its thin-film, lightweight, fast-response, wide-viewing-angle, high-contrast, and low-power attributes, OLEDs promise to be one of the major flat- [16±20]However, the development of highly efficient blue-light-emitting phosphorescent emitters in OLEDs, indispensable for the realization of RGB full-color displays and WOLEDs, is still in its infancy, and blue-light-emitting phosphorescent EL performance lags far behind that of the green-or red-light emitters.One of the best known triplet-state blue-light emitters is iridium(III) bis(4,6-difluorophenylpyridinato)picolate (FIrpic, Scheme 1).[21±23] Although a reasonably good EQE of about 10 % (or 10 lm W ±1 ) has been reported, its blue-light emission was far from saturated, with 1931 Commission Internationale de L'Eclairage x,y coordinates (CIE x,y ) of (0.17, 0.34) [23] thatwere best characterized as cyan in color. The most recent, and probably only the second phosphorescent blue emitter of practical use, was iridium(III) bis(4¢,6¢-difluorophenylpyridinato)tetrakis(1-pyrazolyl) borate) (FIr6), [24] whose blue OLED showed EQEs of 9±10 % (or 11±14 lm W ±1 ), and whose bluecolor chromaticity had been considerably improved to CIE x,y = 0.16, 0.26. There are a couple of limitations in the usage of phosphorescence-based materials for OLEDs. Compared with the short emission lifetime (scale of nanoseconds) of fluorescent materials, the relatively long phosphorescence lifetimes (microseconds scale) of the iridium complexes may lead to dominant triplet±triplet (T 1 ±T 1 ) annihilation at high currents. Long emission lifetimes also cause a long range of exciton diffusion (> 100 nm) that could get quenched in the adjacent layers of materials in the OLED. Consequently, organic phosphorescent materials are often adopted as dopants dispersed in a suitable host material, usually of high bandgap energies and good carrier transport properties. Arylamino-containing organic substances are usually the host materials of choice to alleviate this situation. This has worked reasonably well for phosphorescent green-or red-light-emitting materials. However, it has been demonstrated that the energy differences in the triplet energies of host and guest materials are very important for the confinement of electro-generated triplet excitons on the dopant molecules.[22±28] In cases of triplet-state bluelight emitters, common arylamino-containing substances, such as 4,4¢-bis(9-carbazolyl)-2,2¢-biphenyl (CBP) simply do not have sufficient triplet-state energy for effective T 1 ±T 1 energy transfer; later, a structurally modified host molecule, 1,3-bis(9-carba...

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Section: ±1mentioning

confidence: 99%

Section: ±1mentioning

confidence: 99%

New Dopant and Host Materials for Blue‐Light‐Emitting Phosphorescent Organic Electroluminescent Devices

Yeh

Chen³

et al. 2005

Advanced Materials

685

232

View full text Add to dashboard Cite

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“…However, it can alter the energy of the excited state by modifying the electron density at the metal center. [23] Thus, the photophysical and electrochemical properties of Ir III complexes can be tuned through controlled functionalization of both the cyclometalated and ancillary ligands. In this overview, we summarize our recent progress in designing functional Ir III complexes and using them as highly efficient electroluminescent materials, sensitizers for Ln III in multimetallic assemblies, and as bioimaging agents.…”

Section: Introductionmentioning

confidence: 99%

Functional Ir^III Complexes and Their Applications

2010

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Iridium complexes are drawing great interest because they exhibit high phosphorescence quantum efficiency. Extensive efforts have been devoted to the molecular design of ligands to achieve phosphorescent emission over a wide range of wavelengths that is compatible with many applications. In this research news article, we focus on materials design to improve the performance of phosphorescent Ir(III) complexes for organic light-emitting diodes (OLEDs), luminescence sensitizers, and biological imaging.

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“…Red [6], green [7] and blue phosphorescent emitter [8][9][10] combinations are needed to produce a full color display or a white light source. Today, stable red, green and blue-green light emitting devices, which fulfill the application requirements, have been demonstrated.…”

Section: Introductionmentioning

confidence: 99%

Investigation of FIrpic in PhOLEDs via LC/MS technique

et al. 2009

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Abstract:The commercial breakthrough of phosphorescent organic white light sources is presently hampered due to the unavailability of a stable blue phosphorescent emitter material. Moreover, only few analytical investigations have been made regarding the chemical degradation of the phosphorescent emitter materials during the processing or the operation of the devices. Organic light emitting devices (OLEDs) containing phosphorescent metal complexes with iridium as central ion were investigated. Special attention was paid to the chemical degradation of the material. The devices were analyzed by means of high performance liquid chromatography coupled with mass spectrometry (HPLC/MS). Electron spray ionization (ESI) was employed as ionization source. Isomerization phenomena of the blue-green emitting heteroleptic iridium complex FIrpic could be observed after the device manufacture and after operation. These findings could give hints on the mechanisms that influence the lifetime of PhOLEDs based on FIrpic or similar blue emitters.© Versita Warsaw and Springer-Verlag Berlin Heidelberg.

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Synthesis and characterization of cyclometalated Ir(III) complexes with pyrazolyl ancillary ligands

Cited by 141 publications

References 77 publications

New Dopant and Host Materials for Blue‐Light‐Emitting Phosphorescent Organic Electroluminescent Devices

New Dopant and Host Materials for Blue‐Light‐Emitting Phosphorescent Organic Electroluminescent Devices

Functional Ir^III Complexes and Their Applications

Investigation of FIrpic in PhOLEDs via LC/MS technique

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Synthesis and characterization of cyclometalated Ir(III) complexes with pyrazolyl ancillary ligands

Cited by 141 publications

References 77 publications

New Dopant and Host Materials for Blue‐Light‐Emitting Phosphorescent Organic Electroluminescent Devices

New Dopant and Host Materials for Blue‐Light‐Emitting Phosphorescent Organic Electroluminescent Devices

Functional IrIII Complexes and Their Applications

Investigation of FIrpic in PhOLEDs via LC/MS technique

Contact Info

Product

Resources

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Functional Ir^III Complexes and Their Applications