- Photoluminescence and electroluminescence of iridium(iii) complexes with 2′,6′-bis(trifluoromethyl)-2,4′-bipyridine and 1,3,4-oxadiazole/1,3,4-thiadiazole derivative ligands
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Using 2′,6′-bis(trifluoromethyl)-2,4′-bipyridine as a monoanionic cyclometalated ligand, 2-(5-(4-(trifluoromethyl)phenyl)-1,3,4-oxadiazol-2-yl)phenol and 2-(5-(4-(trifluoromethyl) phenyl)-1,3,4-thiadiazol-2-yl)phenol as ancillary ligands, two new heteroleptic iridium(iii) complexes (Ir1 and Ir2) were prepared and investigated. The ancillary ligand variations affected their emissions greatly, and the complexes Ir1 and Ir2 emitted green (503 nm) and orange (579 nm) lights, respectively. Moreover, the electron mobility of the two complexes is as high as that of the electron transport material Alq3 (tris-(8-hydroxyquinoline)aluminium), which is useful for their performances in organic light-emitting diodes (OLEDs). The OLEDs with Ir1 as the emitter showed excellent performances with a maximum current efficiency of 74.8 cd A?1, a maximum external quantum efficiency of 27.0%, a maximum power efficiency of 33.4 lm W?1, and the efficiency roll-off is mild. These results suggest that complexes with 1,3,4-oxadiazole/1,3,4-thiadiazole derivatives have potential application as efficient emitters in OLEDs.
- Jing, Yi-Ming,Zhao, Yue,Zheng, You-Xuan
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- Highly efficient orange-red electroluminescence of iridium complexes with good electron mobility
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Two iridium complexes with 1-(2,6-bis(trifluoromethyl)pyridin-4-yl)isoquinoline (tfmpiq) and 4-(2,6-bis(trifluoromethyl)pyridin-4-yl)quinazoline (tfmpqz) main ligands and a tetraphenylimidodiphosphinate (tpip) ancillary ligand were applied in organic light-emitting diodes (OLEDs). The introduction of quinazoline greatly influences the nature of the complex. The quantum yield and the electron mobility of Ir(tfmpqz)2(tpip) are much higher than those of Ir(tfmpiq)2(tpip) (Ir(tfmpiq)2(tpip): Φ: 0.47, μe: 8.93-9.47 × 10-6 cm2 V-1 s-1 under an electric field from 1040 (V cm-1)1/2 to 1300 (V cm-1)1/2; Ir(tfmpqz)2(tpip): Φ: 0.98, μe: 6.44-7.20 × 10-6 cm2 V-1 s-1 under an electric field from 1040 (V cm-1)1/2 to 1300 (V cm-1)1/2). In addition, the Ir(tfmpqz)2(tpip)-based device also displayed better performance than that using Ir(tfmpiq)2(tpip). Furthermore, with a europium complex, Eu(DBM)3phen (DBM = dibenzoylmethide; phen = 1,10-phenanthroline) as a sensitizer, the device based on Ir(tfmpqz)2(tpip) with a double emissive layer structure of ITO/MoO3 (3 nm)/TAPC (50 nm)/Ir(tfmpqz)2(tpip) (5 wt%):TcTa (10 nm)/Eu(DBM)3phen (0.2 wt%):Ir(tfmpqz)2(tpip) (5 wt%):26DCzPPy (10 nm)/TmPyPB (50 nm)/LiF (1 nm)/Al (100 nm) displayed the best performance with a maximum luminance of 129466 cd m-2, and a maximum current efficiency and a maximum power efficiency of 62.96 cd A-1 and 53.43 lm W-1, respectively, with low efficiency roll-off. The current efficiency still remains as high as 58.84 cd A-1 at a brightness of 1000 cd m-2 and 53.27 cd A-1 at a brightness of 5000 cd m-2. These results suggest that Ir(iii) complexes with quinazoline units are potential orange-red phosphorescent materials for OLEDs.
- Han, Hua-Bo,Cui, Rong-Zhen,Jing, Yi-Ming,Lu, Guang-Zhao,Zheng, You-Xuan,Zhou, Liang,Zuo, Jing-Lin,Zhang, Hongjie
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- Versatile functionalization of trifluoromethyl based deep blue thermally activated delayed fluorescence materials for organic light emitting diodes
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Thermally activated delayed fluorescence (TADF) materials have been thoroughly developed and have proven to be the most promising means to generate an efficient deep blue emission. In this work, we prepared a series of deep blue TADF emitters based on trifluoromethyl featuring phenyl and N-heterocyclic rings as electron-withdrawing units and carbazole as electron-donating moieties. Efficient organic light-emitting diodes (OLEDs) utilizing these emitters have a deep blue emission and a high external quantum efficiency of up to 20.4%. These blue emitters are among the bluest in the TADF based OLED category. They can also be implemented in OLED as hosts for green phosphorescent iridium(iii) complexes, exhibiting high brightness and a decent external quantum yield.
- Liang, Xiao,Han, Hua-Bo,Yan, Zhi-Ping,Liu, Liang,Zheng, You-Xuan,Meng, Hong,Huang, Wei
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- Efficient orange-red electroluminescence of iridium complexes with 1-(2,6-bis(trifluoromethyl)pyridin-4-yl)isoquinoline and 4-(2,6-bis(trifluoromethyl)pyridin-4-yl)quinazoline ligands
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Two novel iridium(iii) complexes, Ir(tfmpiq)2(acac) (tfmpiq = 1-(2,6-bis(trifluoromethyl)pyridin-4-yl)isoquinoline, acac = acetylacetone) and Ir(tfmpqz)2(acac) (tfmpqz = 4-(2,6-bis(trifluoromethyl)pyridin-4-yl)quinazoline), were synthesized and thoroughly investigated. Both complexes emit orange-red photoluminescence with high quantum yields (Ir(tfmpiq)2(acac): λmax: 587 nm, ηPL: 42%; Ir(tfmpqz)2(acac): λmax: 588 nm, ηPL: 91%). Furthermore, the complex containing quinazoline shows higher electron mobility than that with isoquinoline. The organic light-emitting diodes (OLEDs) with single- or double-emitting layers (EML) were fabricated using two new emitters. The double-EML device using Ir(tfmpqz)2(acac) with the structure of ITO (indium-tin-oxide)/MoO3 (molybdenum oxide, 3 nm)/TAPC (di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane, 50 nm)/Ir(tfmpqz)2(acac) (1 wt%):TcTa (4,4′,4′′-tris(carbazole-9-yl)triphenylamine, 10 nm)/Ir(tfmpqz)2(acac) (1 wt%):2,6DCzPPy (2,6-bis(3-(carbazol-9-yl)phenyl)pyridine, 10 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 50 nm)/LiF (1 nm)/Al (100 nm) displays good electroluminescence performances with a maximum luminance of 96 609 cd m-2, a maximum current efficiency of 59.09 cd A-1, a maximum external quantum efficiency of 20.2%, a maximum power efficiency of 53.61 lm W-1, and the efficiency roll-off ratio is mild.
- Han, Hua-Bo,Cui, Rong-Zhen,Lu, Guang-Zhao,Wu, Zheng-Guang,Zheng, You-Xuan,Zhou, Liang,Zhang, Hongjie
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- Efficient OLEDs with low efficiency roll-off using iridium complexes possessing good electron mobility
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Two bis-cyclometalated iridium complexes (Ir1 and Ir2) with trifluoromethyl substituted bipyridine (2′,6′-bis(trifluoromethyl)-2,3′-bipyridine (L1) and 2′,6′-bis(trifluoromethyl)-2,4′-bipyridine (L2)) as the main ligands and tetraphenylimidodiphosphinate
- Xu, Qiu-Lei,Liang, Xiao,Zhang, Song,Jing, Yi-Ming,Liu, Xuan,Lu, Guang-Zhao,Zheng, You-Xuan,Zuo, Jing-Lin
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- Fast synthesis of iridium(iii) complexes with sulfur-containing ancillary ligand for high-performance green OLEDs with EQE exceeding 31%
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Three green iridium(iii) cyclometalated complexes, namely, (4tfmppy)2Ir(dipdtc), (24btfmppy)2Ir(dipdtc), and (TN4T)2Ir(dipdtc), with the sulfur-containing ancillary ligand N,N-diisopropyldithiocarbamate (dipdtc)
- Lu, Guang-Zhao,Tu, Zhen-Long,Liu, Liang,Zhang, Wen-Wei,Zheng, You-Xuan
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- High efficiency electroluminescence of orange-red iridium(III) complexes for OLEDs with an EQE over 30%
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In this study, three pyrazol-pyridine ligands, 2-(3-methyl-1H-pyrazol-5-yl)pyridine (mepzpy), 2-(3-(trifluoromethyl)-1H-pyrazol-5-yl)pyridine (cf3pzpy), and 2-(3-phenyl-1H-pyrazol-5-yl)pyridine (phpzpy) were successfully synthesized for three orange-red iridium (III) complexes Ir1, Ir2, and Ir3, respectively, in which (2,6-bis(trifluoromethyl)pyridin-4-yl)isoquinoline (BTPIQ) was applied as main ligand. Their single crystals were obtained by vacuum sublimation. They showed distinct photoluminescent emissions at 583 nm with a shoulder peak at 624 nm, with high phosphorescence quantum yields of up to 89%. Organic light-emitting devices (OLEDs) with these complexes as emitters exhibits good performances. Especially, the device with Ir3 complex achieves the best performance with a maximum luminance of 24,188 cd m?2, and a highest external quantum efficiency of 30.65%. This research proved that Ir(III) complexes show highly enhanced performance by the modification of electro-donating benzene ring group into ancillary ligands, which also offers us an efficient strategy to obtain high efficiency orange-red Ir(III) complexes for OLEDs.
- Li, Shuaibing,Qu, Junle,Song, Jun,Su, Ning,Yang, Kun,Zhou, Feifan,Zhou, Liang
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- Two green iridium(iii) complexes containing the electron-transporting group of 4-phenyl-4H-1,2,4-triazole for highly efficient OLEDs
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Two new iridium(iii) cyclometalated complexes (Ir-TN3T and Ir-TN4T) with 2′,6′-bis(trifluoromethyl)-2,3′-bipyridine (TN3T) and 2′,6′-bis(trifluoromethyl)-2,4′-bipyridine (TN4T) as the cyclometalated ligands and
- Lu, Guang-Zhao,Liu, Liang,Tu, Zhen-Long,Zhou, Yong-Hui,Zheng, You-Xuan
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supporting information
p. 2022 - 2028
(2019/02/24)
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- Efficient green photoluminescence and electroluminescence of iridium complexes with high electron mobility
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Aiming to balance the injection and transport of electrons and holes, nitrogen heterocycle and 1,3,4-oxadiazole derivatives were introduced in iridium(iii) complexes to obtain organic light-emitting diodes (OLEDs) with high performances. Thus, two novel Ir(iii) complexes (Ir(tfmphpm)2(pop) and Ir(tfmppm)2(pop)) with green emissions using 2-(3,5-bis(trifluoromethyl)phenyl)pyrimidine (tfmphpm) and 2-(2,6-bis(trifluoromethyl)pyridin-4-yl)pyrimidine (tfmppm) as cyclometalating ligands, and 2-(5-phenyl-1,3,4-oxadiazol-2-yl)phenol (pop) as an ancillary ligand were synthesized. Both emitters show high photoluminescence efficiencies up to 94% and good electron mobility. The devices using two emitters with the structure of ITO (indium-tin-oxide)/MoO3 (molybdenum oxide, 5 nm)/TAPC (di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane, 30 nm)/mCP (1,3-bis(9H-carbazol-9-yl)benzene, 5 nm)/Ir(iii) complexes (6 wt%):PPO21 (3-(diphenylphosphoryl)-9-(4-(diphenylphosphoryl)phenyl)-9H-carbazole, 10 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl) benzene, 40 nm)/LiF (1 nm)/Al (100 nm) display good electroluminescence performances with a maximum luminance of 48981 cd m2, a maximum current efficiency of 92.79 cd A1 and a maximum external quantum efficiency up to 31.8%, respectively, and the efficiency roll-off ratio is low, suggesting that they have potential application in OLEDs.
- Han, Hua-Bo,Wu, Zheng-Guang,Yan, Zhi-Ping,Zhao, Yue,Zheng, You-Xuan
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p. 16543 - 16550
(2018/12/05)
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- Highly efficient bluish green organic light-emitting diodes of iridium(iii) complexes with low efficiency roll-off
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Two novel iridium(iii) complexes Ir(BTBP)2mepzpy and Ir(BTBP)2phpzpy were successfully synthesized, in which 2′,6′-bis(trifluoromethyl)-2,4′-bipyridine (BTBP) was used as the main ligand, and 2-(3-methyl-1H-pyrazol-5-yl)pyridine (mep
- Su, Ning,Wu, Zheng-Guang,Zheng, You-Xuan
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p. 7587 - 7593
(2018/06/15)
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- Orange red iridium complexes with good electron mobility and mild OLED efficiency roll-off
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Two iridium(III) complexes with 1-(3,5-bis(trifluoromethyl)-pyridin-4-yl)isoquinoline (tntpiq) as main ligand, 2-(5-pyridin-4-yl)-1,3,4-oxadiazol-2-yl)phenol (pop) and 2-(5-pyridin-4-yl)-1,3,4-thiadiazol-2-yl)phenol (psp) as ancillary ligands were investigated. Both complexes emit orange red lights with different photoluminescence efficiencies (Ir(tntpiq)2(pop): λem = 585 nm, Φ = 0.41 and Ir(tntpiq)2(psp): λem = 590 nm, Φ = 0.59). Moreover, the electron mobility values of the two complexes are higher than that of the electron transport material Alq3 (tris(8-hydroxyquinoline)aluminium), which are beneficial for their performances in organic light-emitting diodes (OLEDs). The devices with a structure of ITO/MoO3 (3 nm)/TAPC (1,1-bis[4-[N,N-di(p-tolyl)amino]pyridin-4-yl]cyclohexane, 30 nm)/Ir(III) complexes (2 wt%): 26DCzPPy (2,6-bis(3-(carbazol-9-yl)pyridin-4-yl)pyridine, 10 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-pyridin-4-yl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) displayed similar performances with a maximum current efficiency of 24.3 cd A?1 and a maximum external quantum efficiency of 11.6%, respectively, and the efficiency roll-off is very mild.
- Zhou, Yong-Hui,Jiang, Dong,Zheng, You-Xuan
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- Photoluminescence and electroluminescence of an iridium(iii) complex with 2′,6′-bis(trifluoromethyl)-2,4′-bipyridine and 2-(5-phenyl-1,3,4-thiadiazol-2-yl)phenol ligands
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Using electron transport units containing 2′,6′-bis(trifluoromethyl)-2,4′-bipyridine as the main ligand and 2-(5-phenyl-1,3,4-thiadiazol-2-yl)phenol as the ancillary ligand, an iridium(iii) complex (Ir(BTBP)2TDZ) was synthesized, characterized and investigated in detail. The greenish yellow photoluminescence spectrum peaks at 551 nm with a quantum yield of 44%. Organic light-emitting diodes (OLEDs) using Ir(BTBP)2TDZ as the emitter with a single light emitting layer (DS) and double light emitting layers (DD) were fabricated; the DS device exhibited better performances with a maximum current efficiency, power efficiency and external quantum efficiency of up to 54.5 cd A-1, 31.1 lm W-1 and 16.1%, respectively. The results suggest that the iridium complex with the 1,3,4-thiadiazole derivative has potential application in efficient OLEDs.
- Jing, Yi-Ming,Zheng, You-Xuan
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p. 3029 - 3035
(2017/04/14)
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