[(O∧N∧N)PtX] Complexes as a New Class of Light-Emitting Materials for Electrophosphorescent Devices

Kwok, Chi‐Chung; Ngai, Hugo M. Y.; Chan, Siu‐Chung; Sham, Iona H. T.; Che, Chi‐Ming; Zhu, Nianyong

doi:10.1021/ic050365q

Cited by 53 publications

(30 citation statements)

References 16 publications

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“…are comparable to those of previously reported cyclometa- [15] (H-O^N^N = 2-(6'-(pyridin-2'-yl)pyridine-2'-yl)phenol). The cyclic voltammograms of complexes 1, 2, 3 a-g, 4 a-d, 5 a-c and 6 a-c in DMF (0.1 mol dm À3 nBu 4 NPF 6 ) reveal one quasi-reversible reduction couple with E 1/2 at À1.71 to À1.91 V vs. E 1/2 of the Cp 2 Fe 0/ + couple and an irreversible oxidation wave at 0.47 to 0.68 V. The electrochemical data are summarised in Table 1.…”

Section: Resultssupporting

confidence: 89%

“…The absorption l max values resemble those of other cyclometalated C^N^N platinA C H T U N G T R E N N U N G um(II) complexes, [10][11][12]15] but with increased absorption extinction coefficients. The photophysical data of 1, 2, 3 a-g, 4 a-d, 5 a-c and 6 a-c are summarised in Table 1, and the corresponding electronic absorption spectra are depicted in Figure 3 and Figures S32-S40.…”

Section: Photophysical Propertiesmentioning

confidence: 55%

“…Similar electronic absorption spectra were reported by Shao et al in the study of platinum(II) complexes of 6-phenyl-4-(9,9-dihexylfluoren-2-yl)-2,2'-bipyridine. [12] The effect of solvent polarity on the UV/Vis absorption spectra of 3 a ( Figure S39) and 6 a ( Figure 4) [10,11,15] Complexes 1, 2, 3 a-g, 4 a-d, 5 a-c and 6 a-c are strongly emissive, with emission quantum yields (F) up to 0.73 in degassed dichloromethane at 298 K. The emission lifetimes (t) of the complexes are in the microsecond time regime, suggesting that the emission in each case originates from the triplet excited state. Complexes 1 and 2 display a structureless emission band at l max = 588 and 568 nm, respectively, and with emission quantum yields of 0.16 and 0.07, respectively, both of which are substantially higher than that of the [PtClA C H T U N G T R E N N U N G (C^N^N)] complex (l max = 565 nm, F = 0.025).…”

Section: Photophysical Propertiesmentioning

confidence: 99%

“…[11a] and [PtCl-A C H T U N G T R E N N U N G (O^N^N)] [15] -based OLEDs. Device B was found to display a similar maximum brightness (27 000 cd m À2 ), with a maximum current efficiency and power efficiency of 14.7 cd A À1 and 9.2 Lm W À1 , respectively (Table 3, Figure 6).…”

mentioning

confidence: 99%

“…Although a number of highly efficient OLED devices have been fabricated using cyclometalated platinum(II) complexes as phosphorescent dopants using the vacuum deposition technique, [10,11,15] the results de- Table 3. Electroluminescence data for 3 a, 3 d, 3 f, 3 g, 5 d, 5 c and 6 c. When the number of fluorene units increases from one to two (3a-g; 5a-c) and from two to four (6a-c), a small red shift in emission energy is observed.…”

mentioning

confidence: 99%

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Synthesis, Photophysical and Electrophosphorescent Properties of Fluorene‐Based Platinum(II) Complexes

Yuen

Kui

Low

et al. 2010

Chemistry A European J

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A series of platinum(II) complexes bearing tridentate cyclometalated C^N^N (C^N^N=6-phenyl-2,2'-bipyridine and π-extended R-C^N^N=3-[6'-(naphthalen-2''-yl)pyridin-2'-yl]isoquinoline) ligands with fluorene units have been synthesised and their photophysical properties have been studied. The fluorene units are incorporated into the cyclometalated ligands by a Suzuki coupling reaction. An increase in the π-conjugation of the cyclometalated ligands confers favourable photophysical properties compared to the 6-phenyl-2,2'-bipyridine analogues. The fluorene-based platinum(II) complexes display vibronic-structured emission bands with λ(max)=558-601 nm, and high emission quantum yields up to 0.76 in degassed dichloromethane. Their emissions are tentatively assigned to excited states with mixed (3)IL/(3)MLCT parentage (IL=intraligand, MLCT=metal-to-ligand charge transfer). The crystal structures of these platinum(II) complexes reveal extensive Pt(II)···π and/or π-π interactions. The fluorene-based platinum(II) complexes are soluble in organic solvents, have high thermal stability with decomposition temperature >350 °C, and can be thermally vacuum-sublimed or solution-processed as phosphorescent dopants for the fabrication of organic light-emitting diodes (OLEDs). A monochromic OLED with 3d as dopant (2 wt%) fabricated by vacuum deposition gave a current efficiency of 14.7 cd A(-1) and maximum brightness of 27000 cd m(-2). A high current efficiency (9.2 cd A(-1)) has been achieved in a solution-processed OLED using complex 3f (5 wt%) doped in a PVK (poly(9-vinylcarbazole)) host.

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Section: Resultssupporting

confidence: 89%

Section: Photophysical Propertiesmentioning

confidence: 55%

Section: Photophysical Propertiesmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Synthesis, Photophysical and Electrophosphorescent Properties of Fluorene‐Based Platinum(II) Complexes

Yuen

Kui

Low

et al. 2010

Chemistry A European J

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Phosphorescent Platinum(II) Materials for OLED Applications

Xiang

Lai

et al. 2007

Highly Efficient OLEDs With Phosphorescent Materials

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Several classes of phosphorescent platinum(II) complexes with high photoluminescence effi ciency and thermal stability are examined. The tunability of photoluminescent properties through modifying the electronic and/or structural character of the auxiliary ligands is discussed. The suitability of phosphorescent platinum(II) materials as emitting dopants in organic light -emitting devices (OLEDs) and the resultant device performances are highlighted. Molecular design of phosphorescent platinum(II) dopants to improve luminous effi ciency and tune electroluminescence energies is demonstrated. Device confi gurations as well as dopant concentrations are optimized to achieve high -performance OLEDs. Introduction Phosphorescent Materials for OLED ApplicationsThe pursuit of high -effi ciency and -brightness organic light -emitting devices (OLEDs) has prompted the development of electrophosphorescent organometallic emitters [1 -3] . The involvement of heavy transition metals in these materials promotes spin -orbit coupling, which potentially harnesses both singlet (25%) and triplet (75%) excitons for electron -hole recombination from electrical excitation, leading to maximum luminous effi ciency. Several accounts of iridium(III) [2] and platinum(II) [3] emitters as dopants in OLEDs have appeared and their device performances have been reported. The intense triplet excited state emission of phosphorescent compounds is an important prerequisite for fabrication of higheffi ciency electroluminescent device. Ma and Che reported the fi rst observation of electroluminescence from triplet metal -to -ligand charge transfer ( 3 MLCT) excited states of transition metal complexes, such as [Os(CN) 2 (PPh 3 ) 2 (Ph 2 bpy)] (Ph 2 bpy = 4,4 ′ -diphenyl -2,2 ′ -bipyridine) [4] .The diverse photoluminescent properties of platinum(II) complexes have attracted attention in OLED applications, and the remarkable variety of highly 259Highly Effi cient OLEDs with Phosphorescent Materials. Edited by H. Yersin

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N^∧C^∧N‐Coordinated Platinum(II) Complexes as Phosphorescent Emitters in High‐Performance Organic Light‐Emitting Devices

Cocchi

Virgili

Fattori

et al. 2007

Adv Funct Materials

197

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A series of terdentate cyclometallated PtII complexes with remarkable luminescence properties are used as new phosphorescence‐emitting dopants in a blended host matrix as the emitting layer, resulting in very high electroluminescence efficiencies. Because of the high phosphorescence quantum yields of these Pt complexes and the efficient energy transfer from both singlet and triplet excited states of the host to the emitting guest, external electroluminescence quantum efficiencies as high as 4–16 % photons per carrier and luminous efficiencies of 15–40 cd A–1 are achieved. Moreover, these high efficiency values were maintained over a four‐decade current intensity span with no significant roll‐off. Tuning of the electroluminescence spectra from the yellow to the green‐bluish region of the chromaticity diagram is obtained simply by changing the substituents at the central 5‐position of the cyclometallating ligand.

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[(O∧N∧N)PtX] Complexes as a New Class of Light-Emitting Materials for Electrophosphorescent Devices

Cited by 53 publications

References 16 publications

Synthesis, Photophysical and Electrophosphorescent Properties of Fluorene‐Based Platinum(II) Complexes

Synthesis, Photophysical and Electrophosphorescent Properties of Fluorene‐Based Platinum(II) Complexes

Phosphorescent Platinum(II) Materials for OLED Applications

N^∧C^∧N‐Coordinated Platinum(II) Complexes as Phosphorescent Emitters in High‐Performance Organic Light‐Emitting Devices

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[(O∧N∧N)PtX] Complexes as a New Class of Light-Emitting Materials for Electrophosphorescent Devices

Cited by 53 publications

References 16 publications

Synthesis, Photophysical and Electrophosphorescent Properties of Fluorene‐Based Platinum(II) Complexes

Synthesis, Photophysical and Electrophosphorescent Properties of Fluorene‐Based Platinum(II) Complexes

Phosphorescent Platinum(II) Materials for OLED Applications

N∧C∧N‐Coordinated Platinum(II) Complexes as Phosphorescent Emitters in High‐Performance Organic Light‐Emitting Devices

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Product

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About

N^∧C^∧N‐Coordinated Platinum(II) Complexes as Phosphorescent Emitters in High‐Performance Organic Light‐Emitting Devices