Co-reporter:Rongzhen Cui, Weiqiang Liu, Liang Zhou, Yanan Li, Yunlong Jiang, Xuesen Zhao, Yingjie Cui, Qi Zhu, Youxuan Zheng, Ruiping Deng, Hongjie Zhang
Dyes and Pigments 2017 Volume 136() pp:361-367
Publication Date(Web):January 2017
DOI:10.1016/j.dyepig.2016.08.068
•Tb(acac)3(phen-Cl) was utilized as sensitizer for the first time in phosphorescent OLEDs.•Tb(acac)3(phen-Cl) exhibited low-lying energy levels and high triplet energy of ligand.•No Tb(III) ion emission was observed in co-doped devices.•Tb(acac)3(phen-Cl) co-doped devices obtained higher brightness, higher efficiencies and even slower efficiency roll-off.An effective device design strategy was reported to realize high performance green organic light-emitting diodes based on iridium complex by employing a trivalent terbium complex as the sensitizer. The low-lying energy levels of utilized terbium complex are beneficial in broadening recombination zone and facilitating carriers' balance on emitter molecules. No terbium ion characteristic emission was observed in co-doped devices ascribed to high triplet energy of the ligand of terbium complex. Consequently, the 0.4 wt% co-doped single light-emitting layer device obtained the maximum external quantum efficiency, current efficiency and power efficiency up to 27.6%, 114.23 cd/A and 101.92 lm/W, respectively. At 3.8 V, this device realized the practical brightness of 1000 cd/m2 with inspiring external quantum efficiency and current efficiency as high as 27.5% and 113.71 cd/A, respectively. While the 0.2 wt% co-doped double light-emitting layers device displayed relatively lower efficiency, but higher brightness up to 205,629 cd/m2.
Co-reporter:Zheng-Guang Wu, You-Xuan Zheng, Liang Zhou, Yi Wang, Yi Pan
Organic Electronics 2017 Volume 42() pp:141-145
Publication Date(Web):March 2017
DOI:10.1016/j.orgel.2016.12.032
•Efficient blue OLEDs were designed and fabricated.•Both blue iridium(III) complexes have good electron mobility.•Double light-emitting layers structure was optimized.High-efficiency blue organic light-emitting diodes were reported by adopting two novel iridium phosphors. Due to phosphoryl moiety in ancillary ligands, both complexes (dfppy)2Ir(ppp) and (dfppy)2Ir(dpp) (dyppy = 2-(2,4-difluorophenyl)pyridine, ppp = phenyl(pyridin-2-yl)phosphinate, dpp = dipyridinylphosphinate) own high electron mobility which can balance the injection and transport of carriers. Furthermore, the double light-emitting layers with TcTa (4,4′,4″-tris(carbazol-9-yl)triphenylamine) and 26DCzPPy (2,6-bis(3-(carbazol-9-yl)phenyl)pyridine) hosts broaden the exciton formation zone and suppress efficiency roll-off. The optimized double light-emitting layers devices exhibited decent performances with peak current efficiency near 50 cd/A and external quantum efficiency above 20% as well as negligible efficiency roll-off.High-efficiency blue organic light-emitting diodes with peak current efficiency near 50 cd/A and external quantum efficiency above 20% as well as negligible efficiency roll-off were reported using iridium phosphors owning high electron mobility and double light-emitting layers structure.
Co-reporter:Rongzhen Cui;Weiqiang Liu;Liang Zhou;Xuesen Zhao;Yunlong Jiang;Youxuan Zheng;Hongjie Zhang
Journal of Materials Chemistry C 2017 vol. 5(Issue 8) pp:2066-2073
Publication Date(Web):2017/02/23
DOI:10.1039/C6TC05542G
In this work, we demonstrated the efficacy and feasibility of utilizing terbium and gadolinium complexes with low-lying energy levels to sensitize red-emitting iridium complexes in organic light-emitting diodes (OLEDs). Compared with devices without the introduction of a sensitizer, the obtained sensitized devices showed remarkably enhanced electroluminescence performances, which can be attributed to improved carrier balance as well as a wider recombination zone. Moreover, characteristic sensitizer emission was invisible in all sensitized devices due to the inferior hole trapping ability of sensitizer molecules. Finally, the sensitized device co-doped with 0.4 wt% of the terbium complex realized superior electroluminescence performances with maximum brightness, current efficiency, power efficiency and external quantum efficiency as high as 145 071 cd m−2, 64.87 cd A−1, 69.11 lm W−1 and 24.7%, respectively. Meanwhile, even at the practical brightness of 1000 cd m−2 (4.0 V), outstanding external quantum efficiency and current efficiency up to 22.7% and 59.7 cd A−1, respectively, were obtained.
Co-reporter:Guang-Zhao Lu, Yi-Ming Jing, Hua-Bo Han, Yu-Liang Fang, and You-Xuan Zheng
Organometallics 2017 Volume 36(Issue 2) pp:
Publication Date(Web):December 22, 2016
DOI:10.1021/acs.organomet.6b00851
Two new platinum(II) cyclometalated complexes with 2-phenylpyridine (Pt1) and 2-(4-trifluoromethyl)phenylpyridine (Pt2) as the main ligands and 2-(5-phenyl-1,3,4-oxadiazol-2-yl)phenol (pop) as the electron-transporting ancillary ligand were developed. The photoluminescence quantum efficiency yields of both green Pt1 and Pt2 phosphors (λmax 490 and 496 nm) are 20.0% and 31.0% in CH2Cl2 solutions, respectively. Efficient OLEDs (organic light emitting diodes) of ITO/TAPC (bis[4-(N,N-ditolylamino)phenyl]cyclohexane, 40 nm)/Pt1 or Pt2 (5 wt %):TCTA (4,4′,4″-tri(carbazoyl-9-yl)triphenylamine, 10 nm)/Pt1 or Pt2 (5 wt %):2,6DCzPPy (2,6-bis(3-(carbazol-9-yl)phenyl)pyridine, 10 nm)/TmPyPB (1,3,5-tris(m-pyrid-3-ylphenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) were fabricated. Particularly, device G1 based on complex Pt1 with 5 wt % doped concentration showed superior performance with a maximum current efficiency (ηmax,c) of 55.6 cd A–1, a maximum power efficiency (ηmax,p) of 52.2 lm W–1, and a maximum external quantum efficiency (EQEmax) of 18.0%. Device G2 with the Pt2 emitter displayed lower efficiency rolloff with ηc values of 48.5 and 43.1 cd A–1 as the luminance reached 5000 and 10000 cd m–2, respectively. These research results demonstrate that the Pt(II) complexes with an ancillary ligand attached with the 1,3,4-oxadiazole group have promising applications in efficient OLEDs.
Co-reporter:Yi-Ming Jing;Yue Zhao
Dalton Transactions 2017 vol. 46(Issue 3) pp:845-853
Publication Date(Web):2017/01/17
DOI:10.1039/C6DT03919G
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.
Co-reporter:Guang-Zhao Lu;Yan Li;Yi-Ming Jing
Dalton Transactions 2017 vol. 46(Issue 1) pp:150-157
Publication Date(Web):2016/12/19
DOI:10.1039/C6DT03991J
Two new platinum(II) cyclometalated complexes with 2-(4-trifluoromethyl)phenylpyridine (4-tfmppy) as the main ligand and tetraphenylimidodiphosphinate (tpip) (Pt-tpip) and tetra(4-fluorophenyl)imidodiphosphinate (ftpip) (Pt-ftpip) as ancillary ligands were developed. Both complexes were green phosphors with photoluminescence quantum efficiency yields of 71.5% and 79.2% in CH2Cl2 solution at room temperature, respectively. The organic light-emitting diodes with a double emissive layers structure of ITO/TAPC (1,1-bis(4-(di-p-tolylamino)phenyl)cyclohexane), 40 nm/Pt-tpip or Pt-ftpip: TcTa (4,4′,4′′-tri(9-carbazoyl)-triphenylamine) (5 wt%, 10 nm)/Pt-tpip or Pt-ftpip: 2,6DCzPPy (2,6-bis(3-(carbazol-9-yl)phenyl)pyridine) (5 wt%, 10 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) showed good performances. In particular, the device based on the Pt-ftpip complex with a 5 wt% doped concentration showed superior performance with a low drive voltage of 3.3 V, a maximum current efficiency of 48.3 cd A−1, a maximum external quantum efficiency of 14.0%, and a maximum power efficiency of 35.7 lm W−1, respectively. Even at a brightness of 1000 cd m−2, a current efficiency of 47.0 cd A−1 could still be obtained, suggesting that the ancillary ligands (tpip and ftpip) can be employed well in Pt(II) complexes, which could find potential applications in OLEDs.
Co-reporter:Yi-Ming Jing;Fang-Zhou Wang;Jing-Lin Zuo
Journal of Materials Chemistry C 2017 vol. 5(Issue 15) pp:3714-3724
Publication Date(Web):2017/04/13
DOI:10.1039/C7TC00348J
Four novel iridium(III) complexes (Ir1–Ir4) containing 2,3-diphenylquinoxaline derivatives with or without fluoro-substituents at different positions (L1: 2,3-diphenylquinoxaline; L2: 6,7-difluoro-2,3-diphenylquinoxaline; L3: 2,3-bis(4-fluorophenyl)quinoxaline; L4: 6,7-difluoro-2,3-bis(4-fluorophenyl)quinoxaline) as the main ligands and tetraphenylimidodiphosphinate as an ancillary ligand were synthesized and thoroughly investigated. All the complexes emit deep red photoluminescence (PL) with high quantum yields (Ir1: λmax: 662 nm, ηPL: 68.2%; Ir2: λmax: 669 nm, ηPL: 60.4%; Ir3: λmax: 639 nm, ηPL: 78.6%; Ir4: λmax: 642 nm, ηPL: 98.3%). Organic light-emitting diodes (OLEDs) with single- or double-emitting layers (EMLs) were fabricated using these new emitters. The double-EML device using Ir4 with a structure of ITO (indium-tin-oxide)/MoO3 (molybdenum oxide, 5 nm)/TAPC (di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane, 30 nm)/TcTa (4,4′,4′′-tris(carbazol-9-yl)triphenylamine): Ir4 (2 wt%, 10 nm)/26DCzPPy (2,6-bis(3-(carbazol-9-yl)phenyl)pyridine): Ir4 (2 wt%, 10 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) displays good electroluminescence (EL) performance with a maximum luminance, current efficiency, power efficiency and external quantum efficiency of up to 25 926 cd m−2, 16.6 cd A−1, 13.7 lm W−1 and 19.9%, respectively, and the efficiency roll-off ratio is mild. The results demonstrated that the number and position of fluoro-substituents can affect both the PL and EL properties of the Ir(III) complexes, which are potential deep red phosphorescent materials for specific applications in OLEDs.
Co-reporter:Zheng-Guang Wu;Xiao Liang;Jie Zhou;Lei Yu;Yi Wang;Yu-Feng Li;Jing-Lin Zuo;Yi Pan
Chemical Communications 2017 vol. 53(Issue 49) pp:6637-6640
Publication Date(Web):2017/06/16
DOI:10.1039/C7CC02433A
On account of the broad utilities of organophosphorus compounds, the development of highly efficient and concise phosphination methods is significantly important and urgent. Herein, we disclose a novel method for the synthesis of phosphorylated heterocycles: versatile intermediate propargylamines serving as a new type of radical acceptors incorporated in P-radicals via a photocatalytic strategy. This reaction proceeds through a cascade phosphinoylation/cyclization/oxidation/aromatization pathway using readily available starting materials under mild conditions of light with excellent atom economy, catalyzed by AgOAc or fac-Ir(ppy)3. One of the phosphorylated quinolines was selected, as an example, as an electron-transporting material for fabricating phosphorescence organic light-emitting diodes displaying excellent electroluminescence performances with a maximum external quantum efficiency of 21.9% with negligible efficiency roll-off ratios.
Co-reporter:Yi-Ming Jing;Jing-Lin Zuo
RSC Advances (2011-Present) 2017 vol. 7(Issue 5) pp:2615-2620
Publication Date(Web):2017/01/04
DOI:10.1039/C6RA27068A
A series of phosphorescent organic light-emitting diodes (OLEDs) with single or double light-emitting layer(s) were fabricated using a green iridium(III) complex Ir(BTBP)2POP containing 2′,6'-bis(trifluoromethyl)-2,4′-bipyridine (BTBP) cyclometalated ligand and 2-(5-phenyl-1,3,4-oxadiazol-2-yl)phenol (POP) ancillary ligand. The single light-emitting layer devices with the structure of ITO/MoO3 (5 nm)/TAPC (1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane, 30 nm)/mCP (N,N′-dicarbazolyl-3,5-benzene, 5 nm)/Ir(BTBP)2POP:PPO21 (3-(diphenylphosphoryl)-9-(4-(diphenylphosphoryl)phenyl)-9H-carbazole, 8 wt%, 10 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) achieved the highest luminance, current efficiency, power efficiency and external quantum efficiency (EQE) up to 47 599 cd m−2, 86.5 cd A−1, 52.2 lm W−1 and 31.0%, respectively. Furthermore, the double EML device with the structure of ITO/MoO3 (5 nm)/TAPC (30 nm)/mCP:Ir(BTBP)2POP (8 wt%, 10 nm)/PPO21:Ir(BTBP)2POP (8 wt%, 10 nm)/TmPyPB (40 nm)/LiF (1 nm)/Al (100 nm) obtained a higher maximum luminance of 49 139 cd m−2 and slightly lower maximum current efficiency, power efficiency and EQE of 75.8 cd A−1, 51.7 lm W−1 and 27.2%, respectively, with lower turn-on voltage. This research suggested that not only the doping concentration but also the thickness of the emissive and electron transport layers strongly affect the EL performances.
Co-reporter:Guang-Zhao Lu, Ning Su, Yan Li, You-Xuan Zheng
Journal of Organometallic Chemistry 2017 Volume 842(Volume 842) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.jorganchem.2017.05.011
•A pair of Pt(II) enantiomer containing (R/S)-4-pinene-2-phenylpyridine as main ligands were developed.•The characterization and properties were investigated.•The device using one complex showed a maximum current efficiency and a power efficiency of 40.4 cd A-1 and 33.7 lm W−1, respectively, with low efficiency roll-off.Two new platinum(II) cyclometallated complexes (R/S)-(pppy)Pt(acac) with chiral (R/S)-4-pinene-2-phenylpyridine (pppy) main ligands and acetylacetone (acac) ancillary ligand have been developed. The complexes are all green phosphors with photoluminescence quantum efficiency yields of 51.6% in CH2Cl2 solutions at room temperature. The electron circular dichroism (ECD) and circularly polarized phosphorescence luminescence (CPPL) spectra were detected for (R/S)-(pppy)Pt(acac) enantiomers. The organic light-emitting diodes with the double emissive layers structure of ITO/TAPC (1,1-bis(4-(di-p-tolylamino)phenyl)cyclohexane, 40 nm/(R)-(pppy)Pt(acac): TCTA (4,4′,4″-tri (9-carbazoyl)-triphenylamine) (5 wt%, 10 nm)/(R)-(pppy)Pt(acac): 2,6DCzPPy (2,6-bis(3-(carbazol-9-yl)phenyl)pyridine) (5 wt%, 10 nm)/TmPyPB (1,3,5-tri (m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) showed good performances. Particularly, device based on complex (R)-(pppy)Pt(acac) with 5 wt% doped concentration showed superior performances with low drive voltage of 3.0 V, a maximum current efficiency of 40.4 cd A−1, a maximum external quantum efficiency of 13.7% and a maximum power efficiency of 33.7 lm W−1, respectively. Even at the brightness of 1000 cd m−2, a current efficiency of 39.1 cd A−1 can still be obtained suggesting that the main ligand chiral 4-pinene-2-phenylpyridine can be employed well in Pt(II) complexes, which would have potential applications in OLEDs.Download high-res image (175KB)Download full-size image
Co-reporter:Guang-Zhao Lu, Hua-Bo Han, Yan Li, You-Xuan Zheng
Dyes and Pigments 2017 Volume 143(Volume 143) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.dyepig.2017.04.016
•Four Pt(II) complexes containing trifluoromethyl-substituted 2-phenylpyridine and tetraphenylimidodiphosphinate ligands were synthesized.•The identification of structures, photophysical property, thermal stability, theoretical calculation, electrochemical and electroluminescent properties were investigated.•Devices showed a maximum luminance of over 39000 cd m−2 and a maximum current efficiency and a power efficiency of 41.0 cd A−1 and 31.0 lm W−1, respectively, with low efficiency roll-off.•The positions of CF3 on the phenyl rings of phenylpyridine affect the photophysical and electroluminescent properties greatly.Four cyclometalated platinum complexes with trifluoromethyl-substituted 2-phenylpyridine at different positions on its phenyl group as the main ligands and tetraphenylimidodiphosphinate as the ancillary ligand, Pt1-Pt4 (Pt1 is a trifluoromethyl-free complex), were prepared, and their X-ray crystallography, photoluminescence, thermal stability, electrochemical analyses, theoretical calculation and EL performances were investigated. The positions of trifluoromethyl groups on the phenyl ring affected the emission spectra of platinum complexes greatly, and their corresponding emission peaks at 504/534, 512/545, 495/526 and 510/542 nm were observed at room temperature, respectively. Constructed with complexes Pt1-Pt4 as the emitters, respectively, the organic light-emitting diodes (OLEDs) with double light emitting layers structure of ITO/TAPC (1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane, 40 nm /Pt complexes (5 wt%): TCTA (4,4′,4″-tri(9-carbazoyl)-triphenylamine, 10 nm /Pt complexes (5 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, 40 nm)/LiF (1 nm)/Al (100 nm) showed good performances. Particularly, device G2 based on 2-trifluoromethyl-substituted complex Pt2 obtained a maximum luminance of 39196 cd m-2, a maximum current efficiency of 40.1 cd A−1 and a maximum power efficiency of 31.0 lm W−1, respectively, with low efficiency roll-off. The results suggested that these complexes Pt1-Pt4 would have potential applications in efficient OLEDs.Highly efficient green OLEDs based on four platinum complexes show a maximum luminance of 39196 cd m−2, a maximum current efficiency of 40.1 cd A−1 and a maximum power efficiency of 31.0 lm W−1, respectively, with low efficiency roll-off.Download high-res image (187KB)Download full-size image
Co-reporter:Yi-Ming Jing
RSC Advances (2011-Present) 2017 vol. 7(Issue 59) pp:37021-37031
Publication Date(Web):2017/07/24
DOI:10.1039/C7RA05530G
Four iridium(III) complexes (Ir1 to Ir4) containing 2,3-diphenylquinoxaline derivatives with or without fluoro-substituted on different positions (L1: 2,3-diphenylquinoxaline; L2: 6,7-difluoro-2,3-diphenylquinoxaline; L3: 2,3-bis(4-fluorophenyl)quinoxaline; L4: 6,7-difluoro-2,3-bis(4-fluorophenyl)quinoxaline) as main ligands and 2-(5-phenyl-1,3,4-oxadiazol-2-yl)phenol (HPOP) as ancillary ligand were synthesized and investigated. All the complexes emit deep red photoluminescence (PL) (Ir1: λmax: 645 nm; Ir2: λmax: 650 nm; Ir3: λmax: 634 nm; Ir4: λmax: 639 nm). Moreover, the electron mobility of the complexes Ir3 and Ir4 is higher than that of the electron transport material Alq3 (tris-(8-hydroxyquinoline)aluminium), which is beneficial for their performances in organic light-emitting diodes (OLEDs). The OLEDs with single- or double-emitting layers (EML) were fabricated using Ir3 or Ir4 as the emitter. The double-EML device using Ir4 with the structure of ITO (indium-tin-oxide)/MoO3 (molybdenum oxide, 5 nm)/TAPC (di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane, 30 nm)/TcTa (4,4′,4′′-tris(carbazol-9-yl) triphenylamine): Ir4 (2 wt%, 10 nm)/26DCzPPy (2,6-bis(3-(carbazol-9-yl)phenyl)pyridine): Ir4 (2 wt%, 10 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) displays good electroluminescence (EL) performances with maximum luminance, current efficiency, power efficiency and external quantum efficiency of up to 20 676 cd m−2, 14.0 cd A−1, 12.0 lm W−1 and 17.8%, respectively, and the efficiency roll-off ratio is mild. The results suggest that the number and position of fluoro-substituents can affect photophysical, electrochemical and electroluminescent properties of the Ir(III) complexes, which are potential deep red phosphorescent materials for specific OLED applications.
Co-reporter:Hua-Bo Han;Rong-Zhen Cui;Yi-Ming Jing;Guang-Zhao Lu;Liang Zhou;Jing-Lin Zuo;Hongjie Zhang
Journal of Materials Chemistry C 2017 vol. 5(Issue 32) pp:8150-8159
Publication Date(Web):2017/08/17
DOI:10.1039/C7TC02117H
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 129 466 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.
Co-reporter:Zheng-Guang Wu;Jie Zhou;Lei Yu;Georgios Karotsis;Yi Wang;Yi Pan
Journal of Materials Chemistry C 2017 vol. 5(Issue 33) pp:8579-8585
Publication Date(Web):2017/08/24
DOI:10.1039/C7TC02828H
Three phosphoryl quinoline derivatives, (2,4-diphenylquinolin-3-yl)diphenylphosphine oxide (QDPO), (2,4-diphenylbenzo[h]quinolin-3-yl)diphenylphosphine oxide (B-QDPO) and (2-([1,1′-biphenyl]-4-yl)-4-phenylquinolin-3-yl)diphenylphosphine oxide (BP-QDPO), comprising two electron-transporting moieties namely a nitrogen heterocycle and a phosphoryl (PO) group, have been designed and synthesized. All materials exhibit suitable LUMO (lowest unoccupied molecular orbital)/HOMO (highest occupied molecular orbital) levels, large triplet energy gaps (ET > 3.1 eV) and excellent thermal stabilities. These materials were utilized as electron transporting materials for fabricating green phosphorescent organic light-emitting diodes with the configuration of indium tin oxide (ITO)/MoO3 (5 nm)/TAPC (di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane) (30 nm)/Ir(tfmppy)2tpip (bis(4-trifluoromethylphenylpyridine-N,C2′)iridium(tetraphenylimido-diphosphinate)) (8 wt%): mCP [1,3-bis(N-carbazolyl)benzene] (10 nm)/QDPO or B-QDPO or BP-QDPO (30 nm)/LiF (1 nm)/Al (100 nm). These devices exhibited decent performances with a peak current efficiency above 80 cd A−1 and an external quantum efficiency above 20% as well as negligible efficiency roll-off.
Co-reporter:Hua-Bo Han;Rong-Zhen Cui;Guang-Zhao Lu;Zheng-Guang Wu;Liang Zhou;Hongjie Zhang
Dalton Transactions 2017 vol. 46(Issue 43) pp:14916-14925
Publication Date(Web):2017/11/07
DOI:10.1039/C7DT03310A
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.
Co-reporter:Yi-Ming Jing
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 8) pp:3029-3035
Publication Date(Web):2017/04/10
DOI:10.1039/C7NJ00163K
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.
Co-reporter:Yong-Hui Zhou, Jing Xu, Zheng-Guang Wu, You-Xuan Zheng
Journal of Organometallic Chemistry 2017 Volume 848(Volume 848) pp:
Publication Date(Web):15 October 2017
DOI:10.1016/j.jorganchem.2017.07.039
•One efficient green iridium(III) complex was synthesized.•The complex shows good thermal stability.•The OLED based on this complex displays maximum current efficiency of 54.29 cd/A.•The device shows low efficiency roll-off.Using 2-(2,4-difluorophenyl)-4-(trifluoromethyl)pyrimidine as main ligand and tetraphenylimidodiphosphinate as ancillary ligand, one iridium complex was synthesized. This complex shows a green emission peaking at 543 nm with a quantum efficiency yield as 48% in deareated CH2Cl2 solution. It also has good thermal stability with a decomposition temperature of 351 °C. Using this material as emitter, the organic light-emitting diode shows good performances with a maximum luminance 42 898 cd/m2, a maximum current efficiency up to 54.29 cd/A with low efficiency roll-off. At the luminance of 5000 and 10 000 cd/m2, the current efficiencies are still kept at 46.70 and 40.63 cd/A, respectively.Download high-res image (158KB)Download full-size image
Co-reporter:Qiu-Lei Xu, Xiao Liang, Liang Jiang, Yue Zhao and You-Xuan Zheng
Dalton Transactions 2016 vol. 45(Issue 17) pp:7366-7372
Publication Date(Web):11 Mar 2016
DOI:10.1039/C6DT00518G
Three bis-cyclometalated iridium complexes ((TPP)2Ir(acac), (TPP)2Ir(tpip) and (TPP)2Ir(pic)) with 2-(2-trifluoromethyl)pyrimidine-pyridine (TPP) as the main ligand, 2,4-pentanedionate (acac), tetraphenylimidodiphosphinate (tpip) and picolinate (pic) as the ancillary ligands, respectively, were prepared. Their photoluminescence and electrochemistry properties were investigated in detail, and (TPP)2Ir(tpip) was also examined by X-ray crystallography. These complexes show bluish green emission with a quantum efficiency of 11–14%. The organic light emitting diodes (OLEDs) with the structure of ITO/TAPC (1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane, 40 nm)/mCP (1,3-bis(9H-carbazol-9-yl)benzene, 10 nm)/Ir complex (8 wt%):PPO21 (3-(diphenylphosphoryl)-9-(4-(diphenylphosphoryl)phenyl)-9H-carbazole, 25 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 50 nm)/LiF (1 nm)/Al (100 nm) were fabricated to evaluate the potential application of these complexes. A (TPP)2Ir(tpip) emitter based device showed the best performance of a maximum current efficiency (ηc) value of 37.61 cd A−1 and a maximum external quantum efficiency (EQE) of 13.7% with low efficiency roll-off.
Co-reporter:Xuesen Zhao, Liang Zhou, Yunlong Jiang, Rongzhen Cui, Yanan Li, Youxuan Zheng, Jinglin Zuo, Hongjie Zhang
Organic Electronics 2016 Volume 37() pp:85-92
Publication Date(Web):October 2016
DOI:10.1016/j.orgel.2016.06.025
•Efficient green electroluminescent devices were fabricated.•Blue iridium complexes with wide energy gap were utilized as sensitizers.•Sensitizer molecules within light-emitting layer function as electron trappers.•Sensitizer with lower energy levels has better sensitization effect.In this work, electroluminescent (EL) performances of a green iridium complex (tfmppy)2Ir(tpip) were significantly improved by utilizing wide energy gap iridium complexes FK306 and FIrpic as sensitizers. Due to the low-lying energy levels, the co-doped FK306 or FIrpic molecules function as electron trappers, which are helpful in balancing holes and electrons on (tfmppy)2Ir(tpip) molecules and in broadening exciton recombination zone. Consequently, the co-doped devices displayed high EL efficiencies and slow efficiency roll-off. Compared with FIrpic, FK306 acts as a more effective sensitizer because of its relatively lower energy levels. Consequently, highly efficient green EL device with maximum current efficiency, power efficiency and brightness up to 102.29 cd/A (external quantum efficiency (EQE) of 25.3%), 88.67 lm/W and 96,268 cd/m2, respectively, was realized by optimizing the co-doping concentration of FK306. Even at the practical brightness of 1000 cd/m2, EL current efficiency up to 92.93 cd/A (EQE = 23%) can still be retained.Highly efficient green EL device with maximum current efficiency, power efficiency and brightness up to 102.29 cd/A (external quantum efficiency (EQE) of 25.3%), 88.67 lm/W and 96,268 cd/m2, respectively, was realized by optimizing the co-doping concentration of a wide energy gap blue iridium complex FK306 as sensitizer.
Co-reporter:Tian-Yi Li, Hua-Chao Chen, Yi-Ming Jing, Hua-Bo Han, Xiao Liang, You-Xuan Zheng, Wei-Jiang He
Chinese Chemical Letters 2016 Volume 27(Issue 10) pp:1582-1585
Publication Date(Web):October 2016
DOI:10.1016/j.cclet.2016.04.004
Two new iridium complexes, (dfppy)2Ir(l-alanine) (dfppy = 2-(2,4-difluorophenyl)pyridine) and (piq)2Ir(l-alanine) (piq = 1-phenylisoquinoline) were prepared with l-alanine as ancillary ligand. The two complexes show bright greenish-blue and red emission respectively. Theoretic study demonstrated that the emission nature of these complexes is mainly determined by the main ligand. And their improved aqueous solubility and the retained quantum yield favor their application in cell imaging. Intracellular imaging suggested that these two complexes have fine cell membrane permeability and is mainly distributed in cytoplasm. This study displayed a new strategy to design aqueous soluble phosphorescent cyclometallated Ir(III) complex via introducing amino acid as ancillary ligand.Two neutral iridium(III) complexes with l-alanine as ancillary ligand were applied practically in cell imaging as the phosphorescent agent due to the fine biocompatibility and water solubility. The imaging experiments in human gastric cancer SGC-7901 cells demonstrate that these Ir(III) complexes can be utilized in aqueous cell culture media and intracellular microenvironment.
Co-reporter:Song Zhang, Qiu-Lei Xu, Jing-Cheng Xia, Yi-Ming Jing, You-Xuan Zheng and Jing-Lin Zuo
Journal of Materials Chemistry A 2015 vol. 3(Issue 43) pp:11540-11547
Publication Date(Web):12 Oct 2015
DOI:10.1039/C5TC02800K
Two bipolar host materials, (4-((4-(naphthalen-1-yl(phenyl)amino)naphthalen-1-yl)(phenyl)amino)phenyl)diphenylphosphine oxide (POpN) and (3-((4-(naphthalen-1-yl(phenyl)amino)naphthalen-1-yl)(phenyl)amino)phenyl)diphenylphosphine oxide (POmN), comprising a hole-transporting N1-(naphthalen-1-yl)-N1,N4-diphenylnaphthalene-1,4-diamine (NPNA2) donor and an electron-transporting phosphine oxide (PO) acceptor at different positions of the phenyl bridge have been synthesized. POpN (glass transition temperature Tg = 119 °C) and POmN (Tg = 115 °C) exhibit high morphological stability. Two yellow phosphorescent organic light-emitting diodes (PhOLEDs, ITO (indium tin oxide)/TAPC (1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane, 40 nm)/POpN or POmN: Ir(bt)2(acac) (bis(2-phenylbenzothiozolato-N,C2′)iridium(acetylacetonate), 15 wt%, 20 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm)) exhibit maximum luminances (Lmax) of 82057 and 78385 cd m−2, maximum current efficiencies (ηc,max) of 68.28 and 44.95 cd A−1, respectively, with low efficiency roll-off.
Co-reporter:Qiu-Lei Xu, Xiao Liang, Song Zhang, Yi-Ming Jing, Xuan Liu, Guang-Zhao Lu, You-Xuan Zheng and Jing-Lin Zuo
Journal of Materials Chemistry A 2015 vol. 3(Issue 15) pp:3694-3701
Publication Date(Web):18 Feb 2015
DOI:10.1039/C5TC00073D
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 as the ancillary ligand were prepared, and their X-ray crystallography, photoluminescence, electrochemistry properties were investigated. The Ir1 and Ir2 complexes show green emissions at about 500 and 502 nm with high quantum efficiencies of 0.63 and 0.93, respectively. Moreover, they also exhibit higher electron mobility than that of Alq3 (tris-(8-hydroxyquinoline)aluminium). The organic light emitting diodes (OLEDs) with the structure of ITO/TAPC (1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane, 40 nm)/mCP (1,3-bis(9H-carbazol-9-yl)benzene, 10 nm)/Ir complex (8 wt%): PPO21 (3-(diphenylphosphoryl)-9-(4-(diphenylphosphoryl)phenyl)-9H-carbazole, 25 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 50 nm)/LiF (1 nm)/Al (100 nm) showed excellent performances, partly due to their high quantum efficiency and high electron mobility. For the devices G1 and G2, the maximum current efficiency (ηc) values are as high as 101.96/99.97 cd A−1 and the maximum external quantum efficiencies of 31.6% and 30.5% with low electroluminescence efficiency roll-off. The ηc data still remain over 90 cd A−1 even at the luminance of 10000 cd m−2, which proves that the complexes have potential applications as efficient green emitters in OLEDs.
Co-reporter:Tian-Yi Li; Xiao Liang; Liang Zhou; Chen Wu; Song Zhang; Xuan Liu; Guang-Zhao Lu; Li-Sha Xue; You-Xuan Zheng;Jing-Lin Zuo
Inorganic Chemistry 2015 Volume 54(Issue 1) pp:161-173
Publication Date(Web):December 11, 2014
DOI:10.1021/ic501949h
With 2-(2,4-difluorophenyl)pyridine (dfppy) as the first cyclometalated ligand and different monoanionic N-heterocyclic carbenes (NHCs) as the second cyclometalated ligands, 16 blue or greenish-blue neutral iridium(III) phosphorescent complexes, (dfppy)2Ir(NHC), were synthesized efficiently. The obtained Ir(III) complexes display typical phosphorescence of 455–485 nm with quantum yields up to 0.73. By modifying the phenyl moiety in the NHCs with electron-withdrawing substituents (e.g., −F or −CF3) or replacing it with N-heteroaromatic rings (pyridine or pyrimidine), the HOMO–LUMO gaps are broadened, and the emissions shift to the more blue region accordingly. Furthermore, to extend the application scope of NHCs as the second cyclometalated ligands, five other Ir(III) complexes from blue to red were synthesized with different first cyclometalated ligands. Finally, the organic light-emitting diodes using one blue emitter exhibit a maximum current efficiency of 37.83 cd A–1, an external quantum efficiency of 10.3%, and a maximum luminance of 8709 cd m–2. Our results demonstrate that NHCs as the second cyclometalated ligands are good candidates for the achievement of efficient phosphorescent Ir(III) complexes and corresponding devices.
Co-reporter:Song Zhang, Li-Sha Xue, Yi-Ming Jing, Xuan Liu, Guang-Zhao Lu, Xiao Liang, Hong-Yan Li, You-Xuan Zheng, Jing-Lin Zuo
Dyes and Pigments 2015 Volume 118() pp:1-8
Publication Date(Web):July 2015
DOI:10.1016/j.dyepig.2015.02.011
•Two new hole transport materials were synthesised.•The materials show high glass transition temperatures.•The derived OLEDs exhibit high efficiencies.•The efficiency roll-off ratios are low for all devices.Two hole transport materials, N-(4-carbazol-9-yl-phenyl)-N′-naphthalen-1-yl-N,N′- diphenyl-naphthalene-1,4-diamine and N-(4-carbazol-9-yl-phenyl)-N′-(4-N,N- phenyl-naphthalene-naphthalen-1-yl)-N,N′-diphenyl-naphthalene-1,4-diamine, were synthesized by the addition of a carbazole moiety on to the dimer or trimer of N-phenyl-1-naphthylamine. Both of these hole transport materials have high glass transition temperatures of 135 and 167 °C, respectively. The green phosphorescent organic light-emitting diodes (PHOLEDs) of ITO (indium tin oxide)/new hole transport material (50 nm)/Ir(tfmppy)2(tpip) (tfmppy = 4-trifluoromethylphenyl-pyridine, tpip = tetraphenylimidodiphosphinate, 8 wt%): mCP (N,N′-dicarbazolyl-3,5-benzene, 25 nm)/TmPyPB (1,3,5-trim-pyrid-3-yl-phenyl)benzene, 50 nm)/LiF (1 nm)/Al (100 nm) exhibit high efficiency (maximum current efficiency (ηc,max) of 113.9 and 108.8 cd A−1 , maximum external quantum efficiency (EQE) of 29.8% and 28.5%, respectively) with a low efficiency roll-off. At 3000 cd m−2 brightness, the ηc values still remain as high as 109.3 and 105.3 cd A−1 , respectively. The device performances proved that these new materials derived from N-phenyl-1-naphthylamine would be promising hole transport materials for PHOLEDs.Two hole transport materials were synthesized, the dimer (CZ-NPNA2) and trimer (CZ-NPNA3) of N-phenyl-1-naphthylamine. Highly efficient OLEDs (ηc,max of −113.9 cd/A, ηp,max of −67.5 lm/W and EQEmax of 29.8% for CZ-NPNA2; ηc,max of −108.8 cd/A, ηp,max of −53.6 lm/W and EQEmax of 28.5% for CZ-NPNA3) are fabricated with low efficiency roll-off ratios.
Co-reporter:Song Zhang, Qiu-Lei Xu, Yi-Ming Jing, Xuan Liu, Guang-Zhao Lu, Xiao Liang, You-Xuan Zheng and Jing-Lin Zuo
RSC Advances 2015 vol. 5(Issue 35) pp:27235-27241
Publication Date(Web):11 Mar 2015
DOI:10.1039/C5RA02475G
Two novel host materials, N1-(naphthalen-1-yl)-N1,N4-diphenyl-N4-(4-(triphenylsilyl)phenyl) naphthalene-1,4-diamine (SiP) and N1-(naphthalen-1-yl)-N1,N4-diphenyl-N4-(3-(triphenylsilyl) phenyl)naphthalene-1,4-diamine (SiM), were synthesised by incorporating a hole-transporting moiety, N1-(naphthalen-1-yl)-N1,N4-diphenylnaphthalene-1,4-diamine (NPNA2) and typical electron-transporting tetraphenylsilane moiety. SiP and SiM materials exhibit high thermal and morphological stability with a glass transition temperature higher than 110 °C and decomposition temperature above 350 °C. Using Ir(bt)2(acac) (bis(2-phenylbenzothiozolato-N,C2′)iridium(acetylacetonate)) as an emitter, yellow phosphorescent organic light-emitting diodes of ITO/TAPC (1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane, 40 nm)/host: Ir(bt)2(acac) (15 wt%, 20 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) show maximum current and power efficiency of 40.81 cd A−1 and 33.60 lm W−1 with low efficiency roll-off. The current efficiency of 40.10 cd A−1 is still observed at the practically useful brightness value of 1000 cd m−2.
Co-reporter:Qiu-Lei Xu, Xiao Liang, Liang Jiang, Yue Zhao and You-Xuan Zheng
RSC Advances 2015 vol. 5(Issue 108) pp:89218-89225
Publication Date(Web):12 Oct 2015
DOI:10.1039/C5RA14837E
Two bis-cyclometalated iridium complexes ((dfpypy)2Ir(tpip) and (dfpypy)2Ir(Ftpip)) with fluorinated substituted bipyridine (2′,6′-difluoro-2,3′-bipyridine, dfpypy) as the main ligand and tetraphenylimidodiphosphinate derivatives (tpip and Ftpip) as the ancillary ligands were prepared, and their X-ray crystallographic, photoluminescence and electrochemical properties were investigated. The (dfpypy)2Ir(tpip) and (dfpypy)2Ir(Ftpip) complexes showed blue emission at 457 nm with quantum efficiency yields of 7.0% and 7.1%, respectively. Organic light emitting diodes (OLEDs) with the structure of ITO/TAPC (1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane, 40 nm)/mCP (1,3-bis(9H-carbazol-9-yl)benzene, 10 nm)/(dfpypy)2Ir(tpip) or (dfpypy)2Ir(Ftpip) (8 wt%): PPO21 (3-(diphenylphosphoryl)-9-(4-(diphenylphosphoryl)phenyl)-9H-carbazole, 25 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 50 nm)/LiF (1 nm)/Al (100 nm) (B2 and B3) exhibit performances with the maximum current efficiency (ηc) values of 22.83 and 20.79 cd A−1, respectively, with low efficiency roll-off. For example, at 100 cd m−2 display brightness, the current efficiencies of devices B2 and B3 are 19.78, 13.74 cd A−1, respectively. At 1000 cd m−2 light brightness, these values are still 20.39 and 20.75 cd A−1, respectively. Even at the high luminance of 5000 cd m−2, these data also remained at 19.95 and 20.08 cd A−1, respectively.
Co-reporter:Song Zhang, Qiu-Lei Xu, Jing-Cheng Xia, Yi-Ming Jing, You-Xuan Zheng and Jing-Lin Zuo
New Journal of Chemistry 2015 vol. 39(Issue 10) pp:7954-7960
Publication Date(Web):28 Jul 2015
DOI:10.1039/C5NJ00939A
Two bipolar host materials, N1-(naphthalen-1-yl)-N1,N4-diphenyl-N4-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl)naphthalene-1,4-diamine (NONP) and N1-(naphthalen-1-yl)-N1,N4-diphenyl-N4-(3-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl)naphthalene-1,4-diamine (NONM), comprising a hole-transporting N1-(naphthalen-1-yl)-N1,N4-diphenylnaphthalene-1,4-diamine (NPNA2) donor and an electron-transporting 1,3,4-oxadiazole (OXD) acceptor at different phenyl bridge positions, have been synthesized. NONP (glass transition temperature Tg = 127 °C) and NONM (Tg = 105 °C) exhibit high morphological stability. The theoretical calculations on both hosts show that the HOMOs (highest occupied molecular orbitals) are mainly dispersed on the electron-donating groups, and the LUMOs (lowest unoccupied molecular orbitals) are predominantly dispersed on the electron-accepting units, suggesting bipolar charge transporting property. Two yellow phosphorescent organic light-emitting diodes (PHOLEDs, ITO (indium tin oxide)/TAPC (1,1-bis[4-(di-p-tolylamino) phenyl]cyclohexane, 40 nm)/host: Ir(bt)2(acac) (bis(2-phenylbenzothiozolato-N,C2′) iridium(acetylacetonate), 15 wt%, 20 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl) benzene, 40 nm)/LiF (1 nm)/Al (100 nm)) fabricated using NONP and NONM as the host and Ir(bt)2(acac) as the emitter exhibit maximum current efficiencies (ηc,max) of 43.2 and 44.4 cd A−1, respectively, with low current efficiency roll-off. The values of 40.4 and 43.6 cd A−1 can still be achieved at the luminance of 3000 cd m−2, respectively.
Co-reporter:Xuan Liu, Song Zhang, Yi-Ming Jin, Guang-Zhao Lu, Liang Jiang, Xiao Liang, Qiu-Lei Xu, You-Xuan Zheng
Journal of Organometallic Chemistry 2015 Volume 785() pp:11-18
Publication Date(Web):1 June 2015
DOI:10.1016/j.jorganchem.2015.02.025
•We synthesize Ir(III) complexes with 1,3,4-oxadiazole and 1,3,4-thiadiazole derivatives.•The complexes own emission peaks from green to red.•This work provides a new way to tune emission of Ir(III) complexes.•The OLEDs show high efficiency with low efficiency roll-off.Six iridium complexes with 2-(2-trifluoromethyl)pyrimidine-pyridine as the main ligand and 2-(5-phenyl-1,3,4-oxadiazol-2-yl)-phenol or 2-(5-phenyl-1,3,4-thiadiazol-2-yl)-phenol derivatives as ancillary ligands were synthesized. The crystal structures of the complexes adopted pseudo-octahedral coordination geometry with the conventional trans-N, cis-C arrangement of main ligand and the ancillary ligand was connected to iridium center by an N atom from 1,3,4-oxadiazole or 1,3,4-thiadiazole group and an O atom from phenol moiety. Electrochemical study confirmed the ancillary ligand variations have effects on the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels. The density functional theory (DFT) calculations suggested that the frontier orbitals and the electronic properties of the complexes can be manipulated by introducing different ancillary ligands. The compositions of LUMO on the 1,3,4-thiadiazole ancillary ligands are higher than that of 1,3,4-oxadiazole derivatives, and the HOMO - LUMO gaps are also decreased. Therefore, the emissions of the complexes with 1,3,4-thiadiazole ancillary ligands are shift from green to red. The organic light-emitting diodes with Ir3 and Ir6 as emitters show maximum current efficiencies of 41.08 and 50.92 cd/A, respectively, with mild efficiency roll-off. This work provides a way to tune the emission and device efficiency of IrIII complexes by introducing of 1,3,4-thiadiazole group in ancillary ligand.Six iridium complexes using 2-(5-phenyl-1,3,4-oxadiazol-2-yl)-phenol or 2-(5-phenyl-1,3,4-thiadiazol-2-yl)-phenol derivatives as ancillary ligands were investigated. The emissions of the complexes with 1,3,4-thiadiazole are shift from green to red. The devices using two emitters show maximum current efficiencies of 41.08 and 50.92 cd/A, respectively, with mild efficiency roll-off.
Co-reporter:Hong-Yan Li, Tian-Yi Li, Ming-Yu Teng, Qiu-Lei Xu, Song Zhang, Yi-Ming Jin, Xuan Liu, You-Xuan Zheng and Jing-Lin Zuo
Journal of Materials Chemistry A 2014 vol. 2(Issue 6) pp:1116-1124
Publication Date(Web):15 Nov 2013
DOI:10.1039/C3TC31915F
Four new iridium(III) cyclometalated complexes (Ir1–Ir4) with 4-trifluoromethylphenylpyridine as the main ligand and 2-(5-phenyl-1,3,4-oxadiazol-2-yl)-phenol and its fluoro/trifluoromethyl substituted derivatives as ancillary ligands have been developed. All complexes are green phosphors (λmax = 519–537 nm) with photoluminescence quantum efficiency yields of 10–53% in CH2Cl2 solutions at room temperature, respectively. The organic light emitting diodes (OLEDs) with the structure of ITO/TAPC (1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane, 60 nm)/Ir complexes (8 wt%):SimCP2 (bis[3,5-di(9H-carbazol-9-yl)phenyl] diphenylsilane, 30 nm)/TPBi (1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl, 90 nm)/LiF (1 nm)/Al (100 nm) show good performances. In particular, device G4 based on complex Ir4 (2-(5-pentafluorophenyl-1,3,4-oxadiazol-2-yl)-phenol as ancillary ligand) showed superior performances with a peak current efficiency (ηc) of 70.48 cd A−1 and a peak external quantum efficiency (ηext, EQE) of 19.7%. This study demonstrates that the ancillary ligand attached with the 1,3,4-oxadiazole group could facilitate charge trapping across the bulk of the device for efficient OLEDs.
Co-reporter:Ming-Yu Teng, Song Zhang, Yi-Ming Jin, Tian-Yi Li, Xuan Liu, Qiu-Lei Xu, Chen Lin, You-Xuan Zheng, Leyong Wang, Jing-Lin Zuo
Dyes and Pigments 2014 Volume 105() pp:105-113
Publication Date(Web):June 2014
DOI:10.1016/j.dyepig.2014.01.033
•We synthesize three novel Ir(III) complexes.•The complexes show efficient green phosphorescence emission.•The OLEDs exhibit high efficiency at high brightness.•The efficiency roll-off ratios are low for all devices.Using 2-(4-trifluoromethyl-6-fluorophenyl)pyridine (tfmfppy) as the cyclometalated ligand and tetraphenylimidodiphosphinate (tpip) derivatives as ancillary ligands, three iridium complexes (1: Ir(tfmfppy)2tpip; 2: Ir(tfmfppy)2ftpip, ftpip = tetra(4-fluorophenyl)imidodiphosphinate; 3: Ir(tfmfppy)2tfmtpip, tfmtpip = tetra(4-trifluoromethylphenyl)imidodiphosphinate) showing phosphorescence at 514, 513 and 508 nm in CH2Cl2 were synthesized, respectively. By using these complexes as emitters, the organic light emitting diodes with the concise configuration of indium tin oxides/1,1-bis(4-(di-p-tolyl-amino)phenyl)cyclohexane (60 nm)/1 or 2 or 3: bis[3,5-di(9H-carbazol-9-yl)phenyl]di-phenyl silane (8 wt%, 30 nm)/1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (90 nm)/lithium fluoride (1 nm)/aluminium (100 nm) showed bright green light with maximum luminance higher than 40 000 cd m−2. The maximum current efficiency (ηc) values for 1, 2 and 3 based devices (GIr1, GIr2 and GIr3) were 77.49, 66.57, and 53.26 cd A−1 at relatively high brightness of 8025, 5286 and 5169 cd m−2, respectively. In addition, the efficiency roll-off ratios from the peak efficiency to the brightness of 10 000 cd m−2 are less than 10% for all the devices. We believe that the good electron mobilities of the phosphorescent emitters lead to the high devices efficiency and low efficiency roll-off. The results suggest that these complexes have potential application in organic light emitting diodes.Three iridium complexes were synthesized using 2-(4-trifluoromethyl-6-fluorophenyl)pyridine and tetraphenylimidodiphosphinate derivatives ligands and applied as emitters in organic light-emitting diodes (OLEDs). The maximum current efficiency (ηc) value for the OLEDs was 77.49 cd A−1 at relatively high brightness of 8025 cd m−2 with low efficiency roll-off ratio.
Co-reporter:Xindong Shi, Jing Wang, Jun Liu, Saijun Huang, Xinkai Wu, Chaoping Chen, Jiangang Lu, Yikai Su, Youxuan Zheng, Woo Young Kim, Gufeng He
Organic Electronics 2014 Volume 15(Issue 4) pp:864-870
Publication Date(Web):April 2014
DOI:10.1016/j.orgel.2014.01.015
•FDTD method is applied in TOLEDs for optical optimization, demonstrating good agreement with experimental data.•A mixed host with bipolar transport property is employed to avoid charge accumulation and broaden the recombination zone.•A current efficiency of 127.0 cd/A at 1000 cd/m2 is obtained, and maintains to 116.3 cd/A at 10,000 cd/m2.•The resulting TOLED exhibits a highly saturated color, as well as hardly detectable color shift with viewing angles.We have successfully applied finite-difference time-domain (FDTD) method in top-emitting organic light-emitting diodes (TOLEDs) for structure optimization, demonstrating good agreement with experimental data. A mixed host with both hole transport and electron transport materials is employed for the green phosphorescent emitter to avoid charge accumulation and broaden the recombination zone. The resulting TOLEDs exhibit ultra-high efficiencies, low current efficiency roll-off, and a highly saturated color, as well as hardly detectable spectrum shift with viewing angles. In particular, a current efficiency of 127.0 cd/A at a luminance of 1000 cd/m2 is obtained, and maintains to 116.3 cd/A at 10,000 cd/m2.Graphical abstract
Co-reporter:Tian-Yi Li, Xiao Liang, Chen Wu, Li-Sha Xue, Qiu-Lei Xu, Song Zhang, Xuan Liu, You-Xuan Zheng, Xiu-Qiang Wang
Journal of Organometallic Chemistry 2014 Volume 755() pp:110-119
Publication Date(Web):1 April 2014
DOI:10.1016/j.jorganchem.2014.01.014
•We synthesize Ir(III) complexes with N-(diphenylphosphoryl)benzamide derivatives.•The complexes emit around 520 nm with various intensities and quantum efficiencies.•The electronic structures of complexes are theoretically investigated.Seven iridium complexes with the general structure of (tfmppy)2Ir(L1–L7) (tfmppy = 4-trifluoromethylphenylpyridine) were synthesized, where ancillary ligands L1–L7 are fluorine- or trifluoromethyl-substituted (–F or –CF3) N-(diphenylphosphoryl)benzamide derivatives. Single crystal X-ray diffraction study was undertaken on all complexes, which showed that each adopted the distorted octahedral coordination geometry with the conventional trans-N, cis-C arrangement in the coordination sphere. Electrochemical study confirmed the electron-withdrawing –F and –CF3 substituents on the ancillary ligands have effects on the IrIII/IV redox couples and HOMO/LUMO energy levels. Density functional theory (DFT) calculation results showed that the HOMOs are composed of Ir 5d orbital (about 55%) and π orbitals of the phenyl rings (about 38%) in tfmppy ligands, whilst the LUMOs are mostly localized on both the phenyl and pyridine rings of tfmppy (about 90%). All the complexes own the similar emission peaks around 520 nm with short phosphorescent decay time about 2 μs at ambient temperature and relatively high internal quantum efficiencies from 37.5 to 61.2%. This work showed that the iridium complexes with N-(diphenylphosphoryl)benzamide derivatives as the ancillary ligands possess the potential as phosphorence dopants in the organic light-emitting diodes (OLEDs).Seven iridium complexes using N-(diphenylphosphoryl)benzamide derivatives as ancillary ligands were synthesized and investigated. All complexes own the similar emission peaks around 520 nm with various intensities and quantum efficiencies from 37.5 to 61.2%, suggesting the effects of the different substituted ancillary ligands.
Co-reporter:Yi-Ming Jin, Cheng-Cheng Wang, Li-Sha Xue, Tian-Yi Li, Song Zhang, Xuan Liu, Xiao Liang, You-Xuan Zheng, Jing-Lin Zuo
Journal of Organometallic Chemistry 2014 Volume 765() pp:39-45
Publication Date(Web):15 August 2014
DOI:10.1016/j.jorganchem.2014.04.030
•We synthesize Ir(III) complexes with 1,3,4-oxadiazol derivatives.•The complexes own green emission peaks with various intensities.•One OLED shows a peak current efficiency of 61.49 cd A−1.Using 2,4,5-trifluorophenylpyridine as a monoanionic cyclometalated ligand, 2-(5-phenyl-1,3,4-oxadiazol-2-yl)phenol, 2-(5-(4-fluorophenyl)-1,3,4-oxadiazol-2-yl)phenol and 2-(5-(4-trifluoro-methylphenyl)-1,3,4-oxadiazol-2-yl)phenol as ancillary ligands, three new heteroleptic iridium(III) complexes (Ir(F3,4,6ppy)2POP, Ir(F3,4,6ppy)2FPOP and Ir(F3,4,6ppy)2CF3POP) were developed. All complexes are green phosphors (λmax = 503–521 nm) with photoluminescence quantum efficiency yields of 12–18% in CH2Cl2 solutions at room temperature, respectively. The organic light emitting diodes (OLEDs) with the structure of ITO/TAPC (1,1-bis(4-(di-p-tolylamino)phenyl)cyclohexane, 60 nm)/Ir(F3,4,6ppy)2POP (6, 8, 10 wt%): SimCP2 (bis(3,5-di(9H-carbazol-9-yl)phenyl)diphenylsilane, 30 nm)/TPBi (1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl, 90 nm)/LiF (1 nm)/Al (100 nm) showed good performances. Particularly, the device with 8 wt% doped concentration exhibited superior performances with a peak current efficiency (ηc) of 61.49 cd A−1 and a peak power efficiency (ηp) of 46.03 lm W−1. Furthermore, the efficiency roll-off ratios from the peak current efficiency to that at the practical luminance of 100 cd m−2 and from 100 cd m−2 to the benchmark brightness of 1000 cd m−2 in this device are low, which are helpful to keep high efficiency at relatively high current density and high luminance.Three new heteroleptic iridium(III) complexes with 1,3,4-oxadiazol containing ancillary ligands were synthesized and the OLEDs using one emitter showed superior performances with a peak current efficiency (ηc) of 61.49 cd A−1 and low efficiency roll-off.
Co-reporter:Hong-Yan Li, Liang Zhou, Ming-Yu Teng, Qiu-Lei Xu, Chen Lin, You-Xuan Zheng, Jing-Lin Zuo, Hong-Jie Zhang and Xiao-Zeng You
Journal of Materials Chemistry A 2013 vol. 1(Issue 3) pp:560-565
Publication Date(Web):31 Oct 2012
DOI:10.1039/C2TC00052K
A new iridium(III) complex Ir(tfmppy)2(tfmtpip) (1, tfmppy = 4-trifluoromethylphenyl-pyridine, tfmtpip = tetra(4-trifluoromethylphenyl)imidodiphosphinate) was synthesized and applied in organic light-emitting diodes (OLEDs). The devices with the structures of ITO/TAPC (1,1-bis[4-[N,N-di(p-tolyl)amino]phenyl]cyclohexane, 40 nm)/1 (x wt%): mCP (N,N′-dicarbazolyl- 3,5-benzene, 20 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) exhibited a maximum power efficiency (ηp,max) of 113.23 lm W−1 and a maximum current efficiency (ηc,max) of 115.39 cd A−1 (0.01342 mA cm2) at the doping level of 5 wt%, which is among the best performances for Ir(III) complex based OLEDs in the green-light-emitting region. Compared with our former work, the excellent device efficiencies are due to the use of TmPyPB as the electron-transporting/hole-blocking layer which has a relatively higher electron mobility than that of TPBi (2,2′,2′′-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)) and the introduction of the –CF3 moiety to the Ir(III) complex, which can increase the electron mobility of the complex. The device performances proved that the complex has potential applications as an efficient green emitter in OLEDs.
Co-reporter:Ignacio Hernández, You-Xuan Zheng, Majid Motevalli, Rendy H. C. Tan, William P. Gillin and Peter B. Wyatt
Chemical Communications 2013 vol. 49(Issue 19) pp:1933-1935
Publication Date(Web):15 Jan 2013
DOI:10.1039/C3CC38610D
New Yb(III) complexes based on the pentachlorotropolonate (pctrop) ligand show enhanced infrared emission when excited in the orange organic chromophore. Yb(pctrop)3(DMF-d7)2 presents the highest reported quantum yield for a nonfluorinated infrared-emitting organolanthanide complex.
Co-reporter:Qiu-Lei Xu, Cheng-Cheng Wang, Tian-Yi Li, Ming-Yu Teng, Song Zhang, Yi-Ming Jing, Xu Yang, Wei-Nan Li, Chen Lin, You-Xuan Zheng, Jing-Lin Zuo, and Xiao-Zeng You
Inorganic Chemistry 2013 Volume 52(Issue 9) pp:4916-4925
Publication Date(Web):April 15, 2013
DOI:10.1021/ic302510p
Five bis-cyclometalated iridium complexes with tifluoromethyl-substituted 2-phenylpyridine (ppy) at different positions of its phenyl group as the main ligands and tetraphenylimidodiphosphinate (tpip) as the ancillary ligand, 2–6 (1 is a trifluoromethyl-free complex), were prepared, and their X-ray crystallography, photoluminescence, and electrochemistry were investigated. The number and positions of trifluoromethyl groups at the phenyl ring of ppy greatly affected the emission spectra of Ir3+ complexes, and their corresponding emission peaks at 533, 502, 524, 480, and 542 nm were observed at room temperature, respectively. Constructed with complexes 2–6 as the emitters, respectively, the organic light-emitting diodes (OLEDs) with the structure of indium–tin oxide/1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane (30 nm)/Ir (x wt %):bis[3,5-bis(9H-carbazol-9-yl)phenyl]diphenylsilane (15 nm)/1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (45 nm)/LiF (1 nm)/Al (100 nm) showed good performances. Particularly, device G4 based on 4-trifluoromethyl-substituted complex 4 with x = 8 wt % obtained a maximum luminance of over 39000 cd m–2 and maximum luminance efficiency (ηL) and power efficiency (ηp) of 50.8 cd A–1 and 29.0 lm W–1, respectively. The results suggested that all of the complexes 2–6 would have potential applications in OLEDs.
Co-reporter:Dong Wang, Qiu-Lei Xu, Song Zhang, Hong-Yan Li, Cheng-Cheng Wang, Tian-Yi Li, Yi-Ming Jing, Wei Huang, You-Xuan Zheng and Gianluca Accorsi
Dalton Transactions 2013 vol. 42(Issue 8) pp:2716-2723
Publication Date(Web):15 Nov 2012
DOI:10.1039/C2DT32154H
Based on 2,2′:6′,2′′-terpyridine ligands (L1), five terpyridine derivatives, namely 4′-carbazol-9-yl-2,2′:6′,2′′-terpyridine (L2), 4′-diphenylamino-2,2′:6′,2′′-terpyridine (L3), 4′-bis(4-tert-butylphenyl)amino-2,2′:6′,2′′-terpyridine (L4), 4′-[naphthalen-1-yl-(phenyl)amino]-2,2′:6′,2′′-terpyridine (L5), 4′-[naphthalen-2-yl(phenyl)amino]-2,2′:6′,2′′-terpyridine (L6) and their corresponding Re(I) complexes ReLnnn(CO)33Cl (n = 1–6) have been synthesized and characterized by elemental analysis and 1H NMR spectroscopy. The X-ray crystal structure of ReL3(CO)33Cl has also been obtained. The luminescence spectra of ReL2(CO)33Cl–ReL5(CO)33Cl, obtained in CH2Cl2 solution at room temperature, show strong dπ (Re) → π* (diimine) MLCT character (λmax ∼ 600 nm) and a small red shift relative to ReL1(CO)33Cl. This, confirmed by the study of the triplet energy levels of the L1–L6 ligands at low temperature (77 K rigid matrix), indicates that the introduction of electron-donating moieties on the terpyridine unit decreases the triplet levels of the ligands, leading to a reduction of the energy gap between d and π* orbitals. In the solid state, upon MLCT excitation, all the complexes show an even stronger emission and a blue spectral shift (λmax ∼ 550 nm) compared to those obtained in solution.
Co-reporter:Jing Wang, Jun Liu, Saijun Huang, Xinkai Wu, Xindong Shi, Chaoping Chen, Zhicheng Ye, Jiangang Lu, Yikai Su, Gufeng He, Youxuan Zheng
Organic Electronics 2013 Volume 14(Issue 11) pp:2854-2858
Publication Date(Web):November 2013
DOI:10.1016/j.orgel.2013.08.006
•High triplet energy and deep HOMO material is used as both light emitting host and hole transporting layer.•Carrier accumulation adjacent to light emitting zone is eliminated.•Co-host structure is utilized to obtain better charge carrier balance and broadened recombination zone.•High efficiency with low roll-off is achieved even at high brightness.Highly efficient green phosphorescent organic light-emitting diodes (PHOLEDs) with low efficiency roll-off at high brightness have been demonstrated with a novel iridium complex. The host material 1,3-bis(carbazol-9-yl)benzene (mCP) with high triplet energy is also used as the hole transporting layer to avoid carrier accumulation near the exciton formation interface and reduce exciton quenching. It provides a new approach for easily fabricating PHOLED with high triplet energy emitter. Moreover, the hole blocking layer is extended into the light emitting layer to form a co-host, realizing better control of the carrier balance and broader recombination zone. As a consequence, a maximum external quantum efficiency of 20.8% and current efficiency of 72.9 cd/A have been achieved, and maintain to 17.4% and 60.7 cd/A even at 10,000 cd/m2, respectively.
Co-reporter:Jing Wang, Jun Liu, Saijun Huang, Xinkai Wu, Xindong Shi, Gufeng He, Youxuan Zheng
Organic Electronics 2013 Volume 14(Issue 10) pp:2682-2686
Publication Date(Web):October 2013
DOI:10.1016/j.orgel.2013.07.011
•Both light emitting hosts are used as transporting layers as well.•Crossfading-host leads to better performance than double-host and co-host.•The external quantum efficiency reaches 21% at 1000 cd/m2 and 19.3% at 10,000 cd/m2.•Similar exciton lifetime in gradient-host and co-host means no impact on roll-off.•Recombination zone is expanded with increasing current density in gradient-host.We report a high efficiency and low efficiency roll-off green phosphorescent organic light emitting diode using both hole- and electron-transporting host materials in a crossfading profile. To eliminate the energy barrier and reduce the charge carrier accumulation, the host materials are used as transporting layers as well, which also simplifies the device fabrication. It is found out that the recombination zone of gradient doping host sample is not only wider but also extended at high current density, which contributes to the suppressed efficiency roll-off at high luminance. An external quantum efficiency of 21.0% at 1000 cd/m2 is obtained, and maintains to 19.3% at 10,000 cd/m2.Graphical abstract
Co-reporter:Cheng-Cheng Wang;Yi-Ming Jing;Tian-Yi Li;Qiu-Lei Xu;Song Zhang;Wei-Nan Li;Jing-Lin Zuo;Xiao-Zeng You;Xiu-Qiang Wang
European Journal of Inorganic Chemistry 2013 Volume 2013( Issue 33) pp:5683-5693
Publication Date(Web):
DOI:10.1002/ejic.201300861
Abstract
Three green-emitting heteroleptic iridium complexes with 2-(4,5,6-trifluorophenyl)pyridine, 2-(3,4,6-trifluorophenyl)pyridine, and 2-(3,4,5-trifluorophenyl)pyridine as main ligands and tetraphenylimidodiphosphinate (tpip) as the ancillary ligand were synthesized and characterized. The positions of the three fluorine atoms on the phenyl ring affect the emission properties of the complexes, and the application of Htpip as the ancillary ligand improves the electron mobility of the complexes to make it comparable to that of the popular electron transport material tris(8-hydroxyquinolinato)aluminium (Alq3) under the same electric fields. The organic light-emitting diodes (OLEDs) based on the above phosphorescent emitters {indium tin oxide (ITO)/1,1-bis[4-(di-p-tolyl-amino)phenyl]cyclohexane (TAPC), 30 nm/Ir complex (x wt.-%)/N,N′-dicarbazolyl-3,5-benzene (mCP), 15 nm/1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBi), 45 nm/LiF (1 nm)/Al (100 nm)} exhibited good performances. The device doped with bis[2-(3,4,6-trifluorophenyl)pyridine](tetraphenylimidodiphosphinato)iridium [Ir(F3,4,6ppy)2(tpip)] (8 wt.-%) showed superior performance with a peak current efficiency (ηc) of 66.36 cd A–1 and a peak external quantum efficiency (ηext, EQE) of 25.7 % at 5.8 V, a maximum power efficiency (ηp) of 48.20 lm W–1 at 4.4 V, and a maximum luminance (Lmax) of 47627 cd m–2 at 12.6 V. Notably, the electroluminescence (EL) efficiency roll-off effects at relatively high current density in all devices are very mild, which helps them to obtain high efficiency at brightness. The results suggest that the three complexes, [Ir(F3,4,6ppy)2(tpip)] especially, would have potential applications in OLEDs.
Co-reporter:Yong-Hui Zhou, Jun Li, Tao Wu, Xiao-Peng Zhao, Qiu-Lei Xu, Xi-Li Li, Ming-Bo Yu, Li-Li Wang, Peng Sun, You-Xuan Zheng
Inorganic Chemistry Communications 2013 Volume 29() pp:18-21
Publication Date(Web):March 2013
DOI:10.1016/j.inoche.2012.11.027
A rhenium(I) complex ReLR,R(CO)3Cl (1) based on a chiral ligand, LR,R = (−)-4,5-pinene-2,2′-bipyridine [(6R)-5,6,7,8-tetrohedro-7,7-dimethyl-3-(2-pyridinyl)-6,8-methanoisoquinoline], was synthesized and characterized. The emission spectrum of 1 shows efficient dπ(Re) → π* (diimine) (MLCT) phosphorescence with a photoluminescence quantum efficiency of 0.035. The excited state lifetimes of Re(I) complex, measured in CH2Cl2 solution (1.82 μs) and solid state (2.15 μs) at room temperature, support the hypothesis of the MLCT character of the emitting state. Single crystal X-ray diffraction analyses show that complex 1 crystallizes in the chiral space group P21 of monoclinic system. The P–E hysteresis loop indicates its obvious ferroelectricity with the remnant polarization (Pr) value of 0.17 μC/cm2 at an applied field of 4.8 kV/cm. To the best of our knowledge, complex 1 represents the first rhenium-based complex reported with ferroelectricity.A new chiral rhenium(I) complex was synthesized and structurally characterized, which shows photoluminescent and ferroelectric properties and represents the first example of rhenium-based complex with ferroelectricity.Highlights► A new chiral rhenium(I) complex with crystal structure characterization ► Displaying photoluminescent and ferroelectric properties. ► Representing the first rhenium-based example with ferroelectricity
Co-reporter:Gao-Feng Wang, Yuan-Zhong Liu, Xue-Tai Chen, You-Xuan Zheng, Zi-Ling Xue
Inorganica Chimica Acta 2013 Volume 394() pp:488-493
Publication Date(Web):1 January 2013
DOI:10.1016/j.ica.2012.09.008
Synthesis, structures and photophysical properties of a series of neutral fac-[Re(CO)3(C^N)Cl] complexes, where C^N is a pyrimidine-functionalized N-heterocyclic carbene [3-methyl-1-(2-pyrimidine)imidazol-2-ylidene, 1; 3-n-butyl-1-(2-pyrimidine)imidazol-2-ylidene, 2; 3-benzyl-1-(2-pyrimidine)imidazol-2-ylidene, 3; 3-mesityl-1-(2-pyrimidine)-imidazol-2-ylidene, 4] are reported. These complexes have been characterized by 1H NMR, 13C NMR, elemental analysis, and IR spectra. Their electrochemical and photophysical behaviors, along with the X-ray crystal structures of 2 and 4, are also reported. In both degassed CH2Cl2 solutions and solid state at room temperature, complexes 1–4 exhibit the emissions at 515–570 nm.Graphical abstractFour rhenium(I) carbonyl complexes containing pyrimidine-functionalized N-heterocyclic carbenes have been prepared and characterized by 1H NMR, 13C NMR, elemental analysis, and IR spectra. Their electrochemical and photophysical behaviors, along with the X-ray crystal structures of 2 and 4, are also reported. In both degassed CH2Cl2 solutions and solid state at room temperature, complexes 1–4 exhibit the emissions at 515–570 nm.Highlights► Four Re(I) carbonyl complexes containing N-heterocyclic carbenes were prepared. ► Two complexes were determined by X-ray diffraction analysis. ► Their electrochemical and photophysical behaviors were studied.
Co-reporter:Qian-Qian Liu, Jiao Geng, Xiao-Xu Wang, Ke-Hua Gu, Wei Huang, You-Xuan Zheng
Polyhedron 2013 59() pp: 52-57
Publication Date(Web):
DOI:10.1016/j.poly.2013.04.036
Co-reporter:Hong-Yan Li, Tian-Yi Li, Quan Liu, Qiu-Lei Xu, Cheng-Cheng Wang, Song Zhang, Chen Lin, Wei Huang, You-Xuan Zheng, Xiu-Qiang Wang
Journal of Organometallic Chemistry 2013 743() pp: 37-43
Publication Date(Web):
DOI:10.1016/j.jorganchem.2013.06.024
Co-reporter:Ming-Yu Teng, Qiu-Lei Xu, Hong-Yan Li, Lin Wu, You-Xuan Zheng, Chen Lin and Leyong Wang
RSC Advances 2012 vol. 2(Issue 27) pp:10175-10178
Publication Date(Web):04 Sep 2012
DOI:10.1039/C2RA20737K
With 9,10-bis(3,3,3-triphenylprop-1-ynyl)anthracene (BTPYA) doped TPBi as an emissive layer, tunable OLED devices exhibited different emission colors (blue, near-white, green-yellow) controlled by the dopant ratio and driving voltage. The emissions were composed of the electrofluorescence of BTPYA, TPBi, and the electromer of BTPYA, an electroplex formed between BTPYA and TPBi.
Co-reporter:Jian Liu, Ming-Yu Teng, Xiao-Peng Zhang, Kai Wang, Cheng-Hui Li, You-Xuan Zheng, Xiao-Zeng You
Organic Electronics 2012 Volume 13(Issue 10) pp:2177-2184
Publication Date(Web):October 2012
DOI:10.1016/j.orgel.2012.06.013
Two novel efficient blue emitters (TTT-1, TTT-2) containing 1,3,5-triazine, thiophene and triphenylamine have been designed and synthesized. Organic light emitting diodes (OLEDs) using these new triazine derivatives as emissive layers, ITO/TAPC (60 nm)/TTT-1 (Device A) or TTT-2 (Device B) (40 nm)/TPBi (60 nm)/LiF (1 nm)/Al (100 nm), were fabricated and tested. The OLEDs exhibited good performances with low turn-on voltage of 3 V, maximum luminance of ca. 8990 cd/m2 for TTT-1 and 15,980 cd/m2 for TTT-2, and maximum luminance efficiency of 4.7 cd/A for TTT-1 and 4.0 cd/A for TTT-2, respectively.Graphical abstractHighlights► We designed and synthesized two new blue emitters containing triazine, thiophene and triphenylamine. ► We examined the application of our emitters in organic light emitting diodes. ► The OLED based on our emitters show very competitive performances.
Co-reporter:Qiu-Lei Xu, Hong-Yan Li, Cheng-Cheng Wang, Song Zhang, Tian-Yi Li, Yi-Ming Jing, You-Xuan Zheng, Wei Huang, Jing-Lin Zuo, Xiao-Zeng You
Inorganica Chimica Acta 2012 Volume 391() pp:50-57
Publication Date(Web):30 August 2012
DOI:10.1016/j.ica.2012.05.010
A series of new fac-triscyclometallated iridium complexes Ir(Ln)3 (n = 1–6) (L1: 2-{4-[5-phenyl-[1,3,4]oxadiazol-2-yl]-phenyl}-pyridine, L2: 2-{4-[5-(4-tert-butyl-phenyl)-[1,3,4] oxadiazol-2-yl]-phenyl}-pyridine, L3: 9-(4-pyridin-2-yl-phenyl)-9H-carbazole, L4: 1-[4-(5-phenyl-[1,3,4]oxadiazol-2-yl)-phenyl]-isoquinoline, L5: 1-{4-[5-(4-tert-butyl-phenyl)-[1,3,4] oxadiazol-2-yl]-phenyl}-isoquinoline, L6: 9-(4-isoquinolin-1-yl-phenyl)-9H-carbazole) based on Ir(ppy)3 (ppy = phenyl-pyridine) and Ir(piq)3 (piq = 1-phenylisoquinoline) were synthesized from Ir(acac)3 and corresponding ligands by a new and effective way using anthracene as a solvent. Single-crystal X-ray diffraction spectra of three complexes were studied and the iridium centers were found to adopt distorted octahedral coordination geometry. UV–Vis, photoluminescence, cyclic voltammetry were employed for studying the photophysical and electrochemical properties. These complexes exhibit intense phosphorescence in toluene solution at room temperature with high quantum efficiencies (0.07–0.58) and submicrosecond lifetimes (0.57–0.87 μs).Graphical abstractBy incorporating hole-transporting carbazole or electron-transporting oxadiazole moieties, six fac-triscylcometallated iridium(III) complexes have been synthesized by a new method with good yield. The Ir(ppy)3 based compounds, Ir(L1)3–Ir(L3)3, show green or yellowish green color centered at ca. 503–540 nm and the Ir(piq)3 based complexes, Ir(L4)3–Ir(L6)3, display red emission located at ca. 611–631 nm due to the MLCT emission. The complexes Ir(L1)3–Ir(L3)3 are potential materials for the application in OLEDs due to the efficient photoluminescence emission and high quantum efficiency Фp.Highlights► We synthesize six iridium(III) complexes with carbazole or oxadiazole moieties. ► The Ir(ppy)3 based compounds show green or yellowish green color (503–540 nm). ► The Ir(piq)3 based complexes display red emission (611–631 nm). ► The complexes Ir(L1)3–Ir(L3)3 are potential materials for the application in OLEDs.
Co-reporter:Ya Liao, Nan Zhou, Jie Qin, Yi-Zhi Li, You-Xuan Zheng, Jing-Lin Zuo
Inorganic Chemistry Communications 2012 Volume 21() pp:104-108
Publication Date(Web):July 2012
DOI:10.1016/j.inoche.2012.04.024
New amide functional tetrathiafulvalene ligands containing naphthyridine moiety (L1–L3) were synthesized. Further coordination reactions of these ligands with Re(CO)5Cl afford three interesting rhenium tricarbonyl complexes, ClRe(CO)3(L). Crystal structures of ClRe(CO)3(L1) (1) and ClRe(CO)3(L2) (2) have been determined. Electrochemical and spectroscopic properties of all compounds are investigated.New amide functional tetrathiafulvalene ligands containing naphthyridine ligands and two rhenium tricarbonyl complexes based on them have been prepared. Electrochemical and spectroscopic behaviors of these compounds have been studied. The results suggest that the redox-active amide functional tetrathiafulvalene ligands are useful for new metal complexes.Highlights► Three amide functional tetrathiafulvalene-based naphthyridine ligands are synthesized. ► Rhenium(I) tricarbonyl complexes based on the ligands are synthesized and characterized. ► The redox-active amide functional tetrathiafulvalene ligands are useful for new metal complexes.
Co-reporter:Xiao-Wei Li, Hong-Yan Li, Gao-Feng Wang, Fei Chen, Yi-Zhi Li, Xue-Tai Chen, You-Xuan Zheng, and Zi-Ling Xue
Organometallics 2012 Volume 31(Issue 10) pp:3829-3835
Publication Date(Web):May 9, 2012
DOI:10.1021/om2006408
Five rhenium(I) tricarbonyl chloride complexes with pyridine-functionalized N-heterocyclic carbenes, Re(CO)3(L)Cl (L = 3-methyl-1-(2-pyridyl)imidazol-2-ylidene (1), 3-methyl-1-(2-picolyl)imidazol-2-ylidene (2), 3-methyl-1-(2-pyridyl)benzimidazolin-2-ylidene (3), 3-methyl-1-(2-picoyl)benzimidazolin-2-ylidene (4), 1-methyl-4-(2-pyridyl)-1,2,4-triazoline-5-ylidene (5)), have been synthesized by silver carbene transmetalation and characterized by elemental analysis, 1H NMR, 13C NMR, and IR spectra. The molecular structures of 3–5 have been determined by single-crystal X-ray diffraction. The electrochemical and photophysical properties of complexes 1, 3, and 5 have been studied. In both degassed CH2Cl2 solution and the solid state at room temperature or 77 K, the emission wavelengths (465–511 nm) of complexes 1, 3, and 5 lie in the blue-green region, which are rare in contrast to the reported rhenium(I) tricarbonyl complexes. The photoluminescence lifetime decays of Re(I) complexes 1, 3, and 5 were measured, and the quantum yields were calculated by using the standard sample ([Ru(bpy)3]2+(Cl–)2 in degassed acetonitrile solution; Φstd = 0.094).
Co-reporter:Yu-Cheng Zhu;Liang Zhou;Hong-Yan Li;Qiu-Lei Xu;Ming-Yu Teng;Jing-Lin Zuo;Hong-Jie Zhang;Xiao-Zeng You
Advanced Materials 2011 Volume 23( Issue 35) pp:4041-4046
Publication Date(Web):
DOI:10.1002/adma.201101792
Co-reporter:Yun-Mei Tao, Hong-Yan Li, Qiu-Lei Xu, Yu-Cheng Zhu, Ling-Chen Kang, You-Xuan Zheng, Jing-Lin Zuo, Xiao-Zeng You
Synthetic Metals 2011 Volume 161(9–10) pp:718-723
Publication Date(Web):May 2011
DOI:10.1016/j.synthmet.2011.01.020
Two new luminescent materials named 4-bromo-7-carbazyl-[2,1,3]-benzothiadiazole (3) and 4,7-dicarbazyl-[2,1,3]-benzothiadiazole (4) were obtained by a modified Ullmann reaction in one step from 4,7-dibromo-[2,1,3]-benzothiadiazole (2) (based on 2,1,3-benzothiadiazole (1, BTD)) and carbazole. The structure and purity of them were characterized by crystal structures, 1H NMR and elemental analysis. Compared with compounds 1 and 2, the compounds 3 and 4 have better optical properties and thermostability due to the introduction of the carbazole moieties, and the compound 4 shows better performances than that of compound 3. For compound 4, a strong absorption peak at 236 nm with a high extinction coefficient up to 1.205 × 105 L·mol·cm−1 and bright green to orange photoluminescence with quantum yields of 9.0%, 48.4%, 51.0% and 75.6% in different solvents of acetonitrile, dichloromethane, ethyl acetate, and diethyl ether, respectively, were measured.
Co-reporter:Hong-Yan Li, Ling-Xiao Cheng, Jing Xiong, Ling-Chen Kang, Qiu-Lei Xu, Yu-Cheng Zhu, Yun-Mei Tao, You-Xuan Zheng, Jing-Lin Zuo, Xiao-Zeng You
Inorganica Chimica Acta 2011 370(1) pp: 398-404
Publication Date(Web):
DOI:10.1016/j.ica.2011.02.012
Co-reporter:Jing Wu, Hong-Yan Li, Qiu-Lei Xu, Yu-Cheng Zhu, Yun-Mei Tao, Huan-Rong Li, You-Xuan Zheng, Jing-Lin Zuo, Xiao-Zeng You
Inorganica Chimica Acta 2010 Volume 363(Issue 11) pp:2394-2400
Publication Date(Web):10 August 2010
DOI:10.1016/j.ica.2010.03.067
A series of new ternary lanthanide complexes Ln(TFNB)3L (where Ln = Eu, Sm, Nd, Er, Yb, TFNB = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedionate, L = 1-(4-carbazolylphenyl)-2-pyridinyl benzimidazole) have been synthesised. The photoluminescence properties and TGA of them are described in detail. The trifluorinated ligand TFNB displays excellent antenna effect to sensitize the Ln(III) ions to emit characteristic spectra. The carbazole-containing ligand L is testified to be an outstanding synergistic ligand. The luminescence properties investigated and the quantum efficiency measured in dichloromethane solution of Eu(TFNB)3L and Sm(TFNB)3L show that the carbazole moiety is good at absorbing energy to sensitize the metal-centered emitting states and can make the complexes more rigid, provide efficient shielding of the Ln(III) core towards external quenching compared with the reference complexes of Eu(TFNB)3(Pybm) and Sm(TFNB)3(Pybm) (Pybm = 2-(2-pyridine)-benzimidazole) which have no carbazole unit. The quantum efficiency of Eu(TFNB)3L in air-equilibrated CH2Cl2 solution is calculated to be 14.8% by using air-equilibrated aqueous [Ru(bpy)3]2+·2Cl− solution as reference sample (Φstd = 2.8%).The luminescence properties of Eu(TFNB)3L and Sm(TFNB)3L show that the carbazole moiety is good at absorbing energy to sensitize the metal-centered emitting states and can make the complexes more rigid, provide efficient shielding of the Ln(III) core towards external quenching compared with the reference complexes without carbazole unit.
Co-reporter:Jing Wu, Hong-Yan Li, Ling-Chen Kang, Dong-Ping Li, Qiu-Lei Xu, Yu-Cheng Zhu, Yun-Mei Tao, You-Xuan Zheng, Jing-Lin Zuo, Xiao-Zeng You
Journal of Organometallic Chemistry 2010 695(17) pp: 2048-2056
Publication Date(Web):
DOI:10.1016/j.jorganchem.2010.04.037
Co-reporter:Jing Wu, Hong-Yan Li, Ling-Chen Kang, Dong-Ping Li, Huan-Rong Li, Xin-Hui Zhou, Yan Sui, You-Xuan Zheng, Jing-Lin Zuo, Xiao-Zeng You
Journal of Photochemistry and Photobiology A: Chemistry 2010 Volume 211(2–3) pp:135-142
Publication Date(Web):15 April 2010
DOI:10.1016/j.jphotochem.2010.02.010
Co-reporter:Yong-Hui Zhou, Liang Zhou, Jing Wu, Hong-Yan Li, You-Xuan Zheng, Xiao-Zeng You, Hong-Jie Zhang
Thin Solid Films 2010 Volume 518(Issue 15) pp:4403-4407
Publication Date(Web):31 May 2010
DOI:10.1016/j.tsf.2010.02.031
The photoluminescence properties of one europium complex Eu(TFNB)3Phen (TFNB = 4,4,4-trifluoro-1-(naphthyl)-1,3-butanedione, Phen = 1,10-phenanthroline) doped in a hole-transporting material CBP (4,4′-N,N′-dicarbazole-biphenyl) films were studied. A series of organic light-emitting devices (OLEDs) using Eu(TFNB)3Phen as the emitter were fabricated with a multilayer structure of indium tin oxide, 250 Ω/square)/TPD (N,N′-diphenyl-N,N′-bis(3-methyllphenyl)-(1,1′-biphenyl)-4,4′-diamine, 50 nm)/Eu(TFNB)3phen (x): CBP (4,4′-N,N′-dicarbazole-biphenyl, 45 nm)/BCP (2,9-dimethyl-4,7-diphenyl-l,10 phenanthroline, 20 nm)/AlQ (tris(8-hydroxy-quinoline) aluminium, 30 nm)/LiF (1 nm)/Al (100 nm), where x is the weight percentage of Eu(TFNB)3phen doped in the CBP matrix (1–6%). A red emission at 612 nm with a half bandwidth of 3 nm, characteristic of Eu(III) ion, was observed with all devices. The device with a 3% dopant concentration shows the maximum luminance up to 1169 cd/m2 (18 V) and the device with a 5% dopant concentration exhibits a current efficiency of 4.46 cd/A and power efficiency of 2.03 lm/W. The mechanism of the electroluminescence was also discussed.
Co-reporter:Hong-Yan Li, Jing Wu, Xin-Hui Zhou, Ling-Chen Kang, Dong-Ping Li, Yan Sui, Yong-Hui Zhou, You-Xuan Zheng, Jing-Lin Zuo and Xiao-Zeng You
Dalton Transactions 2009 (Issue 47) pp:10563-10569
Publication Date(Web):16 Oct 2009
DOI:10.1039/B912823A
Three N,N-bidentate ligands, 5,5′-dibromo-2,2′-bipyridine (L1) and two carbazole containing ligands of 5-bromo-5′-carbazolyl-2,2′-bipyridine (L2), 5,5′-dicarbazolyl-2,2′-bipyridine (L3), and their corresponding rhenium Re(CO)3Cl(L) complexes (ReL1–ReL3) have been successfully synthesized and characterized by elemental analysis, 1H NMR and IR spectra. Their photophysical properties and thermal analysis, along with the X-ray crystal structure analysis of L3 and complexes ReL1 and ReL3 are also described. In CH2Cl2 solution at room temperature, all complexes display intense absorption bands at ca. 220–350 nm, which can be assigned to spin-allowed intraligand (π→π*) transitions, and the low energy broad bands in the 360–480 nm region are attributed to the metal to ligand charge-transfer dπ(Re)→π* (diimine) (MLCT). The introduction of carbazole moieties improves the MLCT absorption and molar extinction coefficient of these complexes. Upon excitation at the peak maxima, all complexes show strong emissions around 620 nm, which are assigned to dπ(Re)→π* (diimine) MLCT phosphorescence. The photoluminescence lifetime decay of Re(I) complexes were measured and the quantum efficiencies of the rhenium(I) complexes were calculated by using air-equilibrated [Ru(bpy)3]2+·2Cl− aqueous solution as standard (Φstd = 0.028). The complexes with appended carbazole moieties exhibit enhanced luminescence performances relative to ReL1.
Co-reporter:Gianluca Accorsi, Nicola Armaroli, François Cardinali, Dong Wang, Youxuan Zheng
Journal of Alloys and Compounds 2009 Volume 485(1–2) pp:119-123
Publication Date(Web):19 October 2009
DOI:10.1016/j.jallcom.2009.06.096
Five Eu(III), four Tb(III) and two Tm(III) multichromophoric complexes (1-Eu, 1-Tb, 2-Eu, 3-Eu, 3-Tb, 3-Tm, 4-Tb, 4-Tm, 5-Eu, 6-Eu and 6-Tb; where 1 = tris[dibenzoylmethanido] (4′-chloro-2,2′:6′,2′′-terpyridine), 2 = tris[dibenzoylmethanido] (4′-(9H-carbazol-9yl)-2,2′:6′,2′′-terpyridine), 3 = tris(1,1,1,5,5,5-hexafluoroacetylacetonato), 4 = tris[1,1,1,5,5,5-hexafluoroacetylacetonato] (tripyridin-2-ylamine), 5 = tris[dibenzoylmethanido][N-(4-(9H-carbazol-9-yl)butyl)-N-(dipyridin-2-yl)amine] and 6 = tris[dibenzoylmethanido][N-(6-(9H-carbazol-9-yl)hexyl)-N-(dipyridin-2-yl)amine]) emitting in the blue (Tm), green (Tb) and red (Eu) spectral regions, have been synthesized and characterized. The complexes involve five different coordinating (2,2′:6′,2′′-terpyridine (terpy); dibenzoylmethane (dbm); 1,1,1,5,5,5-hexafluoroacetylacetonato (hfa), tripyridin-2-ylamine (tri-amine) and N-(dipyridin-2-yl)amine (di-amine)) and one non-coordinating (carbazole) units. The synthesis and photophysical properties of these complexes are reported addressing the influence of the various ligands on the lanthanide metal-centered luminescence in CH2Cl2 solution and solid state matrices.
Co-reporter:Qian Ma, Youxuan Zheng, Nicola Armaroli, Margherita Bolognesi, Gianluca Accorsi
Inorganica Chimica Acta 2009 Volume 362(Issue 9) pp:3181-3186
Publication Date(Web):1 July 2009
DOI:10.1016/j.ica.2009.02.014
Three novel europium complexes, Eu(CCHPD)3Phen = Tris[1-(9H-carbazol-9-yl)-3-[(6-(9H- carbazol-9-yl)hexoxy)-phenyl]-1,3-dione](1,10-phenanthroline) europium(III), Eu(CCHPD)3Bath = Tris[1-(9H-carbazol-9-yl)-3-[(6-(9H-carbazol-9-yl)hexoxy)-phenyl]-1,3-dione](bathophenanthroline) europium(III) and Eu(CPD)3Phen = Tris[1-(9H-carbazol-9-yl)-3-phenylpropane]-1,3-dione](1,10-phenanthroline) europium(III), have been synthesized and characterized (Scheme 1). Involved ligands consist of different chelating and non-chelating units: appended carbazole (Br-Carb), phenanthroline (Phen), bathophenanthroline (Bath) and 1-(9H-carbazol-9-yl)-3-phenylpropane]-1,3-dione (CPD). The luminescence properties show that the carbazole moiety is a better sensitizer for the metal centred (MC) emitting states relative to Phen and Bath. Moreover, its charge-transporting properties make such complexes appealing for their application in electroluminescent devices.Three novel asymmetrical europium complexes involving carbazole units have been synthesized and photophysically investigated. The PL properties of Eu(CCHPD)3Phen and Eu(CCHPD)3Bath both in solution and in solid state, show that the most efficient population of the Eu(III) emitting states, via energy transfer process, occurs from the carbazole units.
Co-reporter:Hong-Yan Li, Jing Wu, Wei Huang, Yong-Hui Zhou, Huan-Rong Li, You-Xuan Zheng, Jing-Lin Zuo
Journal of Photochemistry and Photobiology A: Chemistry 2009 Volume 208(2–3) pp:110-116
Publication Date(Web):15 December 2009
DOI:10.1016/j.jphotochem.2009.09.003
A series of homodinuclear lanthanide complexes Ln2(HTH)6Bpm (where Ln = Eu, Sm, Er, Yb, Pr; HTH = 4,4,5,5,6,6,6-heptafluroro-1-(2-thienyl)hexane-1,3-dione; Bpm = 2,2′-bipyrimidine) were synthesized and the photoluminescence properties of these complexes are described. After ligand-mediated excitation of the complexes, they all show the characteristic luminescence of the corresponding Ln3+ ions in the visible and NIR regions attributed to efficient energy transfer from the ligands to the metal centres. For the Eu2(HTH)6Bpm complex a lifetime of 738.8 μs (100%, χ2 = 1.362) is found in solid and two lifetimes of 455.4 μs (12.88%) and 618.5 μs (87.12%) (χ2 = 1.652) are found in CH2Cl2 solution, respectively. Its quantum efficiency in air-equilibrated CH2Cl2 solution is found to be 28.4%, by using air-equilibrated aqueous [Ru(bpy)3]2+·2Cl− solution as reference sample (Φstd = 2.8%).
Co-reporter:Youxuan Zheng;Francois Cardinali;Nicola Armaroli;Gianluca Accorsi
European Journal of Inorganic Chemistry 2008 Volume 2008( Issue 12) pp:2075-2080
Publication Date(Web):
DOI:10.1002/ejic.200701257
Abstract
Two europium complexes {Eu·dbm·carb·phen = tris[1-{[6-(9H-carbazol-9-yl)hexoxy]phenyl}-3-{[6-(9H-carbazol-9-yl)hexoxy]phenyl}propane-1,3-dione](1,10-phenanthroline)europium(III), Eu·dbm·carb·bath = tris[1-{[6-(9H-carbazol-9-yl)hexoxy]phenyl}-3-{[6-(9H-carbazol-9-yl)hexoxy]phenyl}propane-1,3-dione](bathophenanthroline)europium(III)} and their reference compounds were synthesized and characterized. Each complex contains three different chromophores: carbazole (carb), phenanthroline (phen) (or bathophenanthroline, bath) and dibenzoylmethane (dbm) units. The luminescence properties investigated in dichloromethane solution and in solid matrix show that the carbazole moiety is a better sensitizer for the metal-centred emitting states of the EuIII ion compared to the dibenzoylmethane and phenanthroline units. Furthermore, the charge-transporting properties of the carbazole moieties appear to be appealing when integrated into the emitting units. Finally, the high number of appended carbazole units confers a strong light-harvesting character to the structure.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Co-reporter:Yonghui Zhou, Youxuan Zheng, Olaf Zeika, Horst Hartmann, Karl Leo
Materials Chemistry and Physics 2008 Volume 112(Issue 2) pp:577-579
Publication Date(Web):1 December 2008
DOI:10.1016/j.matchemphys.2008.06.013
New 2,2′-difluoro-1,3,2-dioxaborines with pronounced electron accepting properties have been prepared by reaction of quinizarines/halo-substituted quinizarines with BF3·Et2O. From the results of electrochemical analysis, the electron affinities (EAs) of 1,3,2-dioxaborines can be increased when the hydrogen atoms are replaced by halogen ones. Furthermore, conductance of zinc phthalocyanine (ZnPc), a most versatile organic (photo)conductors used in organic light-emitting diodes (OLEDs), can be enhanced greatly when 4,9,10,11,12-pentachloro-2,2,7,7-tetrafluoro-2,7-dihydro-1,3,6,8-tetraoxa-2,7-dibora-benzo[e]pyrene (4c) doped as charge-transport materials which suggesting halogen substitution is a versatile tool for creating efficient new p-dopants.
Co-reporter:Hong-Yan Li, Jing Wu, Xin-Hui Zhou, Ling-Chen Kang, Dong-Ping Li, Yan Sui, Yong-Hui Zhou, You-Xuan Zheng, Jing-Lin Zuo and Xiao-Zeng You
Dalton Transactions 2009(Issue 47) pp:NaN10569-10569
Publication Date(Web):2009/10/16
DOI:10.1039/B912823A
Three N,N-bidentate ligands, 5,5′-dibromo-2,2′-bipyridine (L1) and two carbazole containing ligands of 5-bromo-5′-carbazolyl-2,2′-bipyridine (L2), 5,5′-dicarbazolyl-2,2′-bipyridine (L3), and their corresponding rhenium Re(CO)3Cl(L) complexes (ReL1–ReL3) have been successfully synthesized and characterized by elemental analysis, 1H NMR and IR spectra. Their photophysical properties and thermal analysis, along with the X-ray crystal structure analysis of L3 and complexes ReL1 and ReL3 are also described. In CH2Cl2 solution at room temperature, all complexes display intense absorption bands at ca. 220–350 nm, which can be assigned to spin-allowed intraligand (π→π*) transitions, and the low energy broad bands in the 360–480 nm region are attributed to the metal to ligand charge-transfer dπ(Re)→π* (diimine) (MLCT). The introduction of carbazole moieties improves the MLCT absorption and molar extinction coefficient of these complexes. Upon excitation at the peak maxima, all complexes show strong emissions around 620 nm, which are assigned to dπ(Re)→π* (diimine) MLCT phosphorescence. The photoluminescence lifetime decay of Re(I) complexes were measured and the quantum efficiencies of the rhenium(I) complexes were calculated by using air-equilibrated [Ru(bpy)3]2+·2Cl− aqueous solution as standard (Φstd = 0.028). The complexes with appended carbazole moieties exhibit enhanced luminescence performances relative to ReL1.
Co-reporter:Rongzhen Cui, Weiqiang Liu, Liang Zhou, Xuesen Zhao, Yunlong Jiang, Youxuan Zheng and Hongjie Zhang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 8) pp:NaN2073-2073
Publication Date(Web):2017/01/24
DOI:10.1039/C6TC05542G
In this work, we demonstrated the efficacy and feasibility of utilizing terbium and gadolinium complexes with low-lying energy levels to sensitize red-emitting iridium complexes in organic light-emitting diodes (OLEDs). Compared with devices without the introduction of a sensitizer, the obtained sensitized devices showed remarkably enhanced electroluminescence performances, which can be attributed to improved carrier balance as well as a wider recombination zone. Moreover, characteristic sensitizer emission was invisible in all sensitized devices due to the inferior hole trapping ability of sensitizer molecules. Finally, the sensitized device co-doped with 0.4 wt% of the terbium complex realized superior electroluminescence performances with maximum brightness, current efficiency, power efficiency and external quantum efficiency as high as 145071 cd m−2, 64.87 cd A−1, 69.11 lm W−1 and 24.7%, respectively. Meanwhile, even at the practical brightness of 1000 cd m−2 (4.0 V), outstanding external quantum efficiency and current efficiency up to 22.7% and 59.7 cd A−1, respectively, were obtained.
Co-reporter:Yi-Ming Jing, Yue Zhao and You-Xuan Zheng
Dalton Transactions 2017 - vol. 46(Issue 3) pp:NaN853-853
Publication Date(Web):2016/12/12
DOI:10.1039/C6DT03919G
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.
Co-reporter:Guang-Zhao Lu, Yan Li, Yi-Ming Jing and You-Xuan Zheng
Dalton Transactions 2017 - vol. 46(Issue 1) pp:NaN157-157
Publication Date(Web):2016/11/15
DOI:10.1039/C6DT03991J
Two new platinum(II) cyclometalated complexes with 2-(4-trifluoromethyl)phenylpyridine (4-tfmppy) as the main ligand and tetraphenylimidodiphosphinate (tpip) (Pt-tpip) and tetra(4-fluorophenyl)imidodiphosphinate (ftpip) (Pt-ftpip) as ancillary ligands were developed. Both complexes were green phosphors with photoluminescence quantum efficiency yields of 71.5% and 79.2% in CH2Cl2 solution at room temperature, respectively. The organic light-emitting diodes with a double emissive layers structure of ITO/TAPC (1,1-bis(4-(di-p-tolylamino)phenyl)cyclohexane), 40 nm/Pt-tpip or Pt-ftpip: TcTa (4,4′,4′′-tri(9-carbazoyl)-triphenylamine) (5 wt%, 10 nm)/Pt-tpip or Pt-ftpip: 2,6DCzPPy (2,6-bis(3-(carbazol-9-yl)phenyl)pyridine) (5 wt%, 10 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) showed good performances. In particular, the device based on the Pt-ftpip complex with a 5 wt% doped concentration showed superior performance with a low drive voltage of 3.3 V, a maximum current efficiency of 48.3 cd A−1, a maximum external quantum efficiency of 14.0%, and a maximum power efficiency of 35.7 lm W−1, respectively. Even at a brightness of 1000 cd m−2, a current efficiency of 47.0 cd A−1 could still be obtained, suggesting that the ancillary ligands (tpip and ftpip) can be employed well in Pt(II) complexes, which could find potential applications in OLEDs.
Co-reporter:Tian-Yi Li, You-Xuan Zheng and Yong-Hui Zhou
Dalton Transactions 2016 - vol. 45(Issue 48) pp:NaN19237-19237
Publication Date(Web):2016/11/14
DOI:10.1039/C6DT04030F
Iridium complexes with a chiral metal center and chiral carbons, Λ/Δ-(dfppy)2Ir(chty-R) and Λ/Δ-(dfppy)2Ir(chty-S), were synthesized and characterized. These isomers have the same steady-state photophysical properties, and obvious offsets in ECD spectra highlight both the chiral sources. Each enantiomeric couple shows mirror-image CPL bands with a dissymmetry factor in the order of 10−3.
Co-reporter:Yi-Ming Jing, Fang-Zhou Wang, You-Xuan Zheng and Jing-Lin Zuo
Journal of Materials Chemistry A 2017 - vol. 5(Issue 15) pp:NaN3724-3724
Publication Date(Web):2017/03/16
DOI:10.1039/C7TC00348J
Four novel iridium(III) complexes (Ir1–Ir4) containing 2,3-diphenylquinoxaline derivatives with or without fluoro-substituents at different positions (L1: 2,3-diphenylquinoxaline; L2: 6,7-difluoro-2,3-diphenylquinoxaline; L3: 2,3-bis(4-fluorophenyl)quinoxaline; L4: 6,7-difluoro-2,3-bis(4-fluorophenyl)quinoxaline) as the main ligands and tetraphenylimidodiphosphinate as an ancillary ligand were synthesized and thoroughly investigated. All the complexes emit deep red photoluminescence (PL) with high quantum yields (Ir1: λmax: 662 nm, ηPL: 68.2%; Ir2: λmax: 669 nm, ηPL: 60.4%; Ir3: λmax: 639 nm, ηPL: 78.6%; Ir4: λmax: 642 nm, ηPL: 98.3%). Organic light-emitting diodes (OLEDs) with single- or double-emitting layers (EMLs) were fabricated using these new emitters. The double-EML device using Ir4 with a structure of ITO (indium-tin-oxide)/MoO3 (molybdenum oxide, 5 nm)/TAPC (di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane, 30 nm)/TcTa (4,4′,4′′-tris(carbazol-9-yl)triphenylamine): Ir4 (2 wt%, 10 nm)/26DCzPPy (2,6-bis(3-(carbazol-9-yl)phenyl)pyridine): Ir4 (2 wt%, 10 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) displays good electroluminescence (EL) performance with a maximum luminance, current efficiency, power efficiency and external quantum efficiency of up to 25926 cd m−2, 16.6 cd A−1, 13.7 lm W−1 and 19.9%, respectively, and the efficiency roll-off ratio is mild. The results demonstrated that the number and position of fluoro-substituents can affect both the PL and EL properties of the Ir(III) complexes, which are potential deep red phosphorescent materials for specific applications in OLEDs.
Co-reporter:Song Zhang, Qiu-Lei Xu, Jing-Cheng Xia, Yi-Ming Jing, You-Xuan Zheng and Jing-Lin Zuo
Journal of Materials Chemistry A 2015 - vol. 3(Issue 43) pp:NaN11547-11547
Publication Date(Web):2015/10/12
DOI:10.1039/C5TC02800K
Two bipolar host materials, (4-((4-(naphthalen-1-yl(phenyl)amino)naphthalen-1-yl)(phenyl)amino)phenyl)diphenylphosphine oxide (POpN) and (3-((4-(naphthalen-1-yl(phenyl)amino)naphthalen-1-yl)(phenyl)amino)phenyl)diphenylphosphine oxide (POmN), comprising a hole-transporting N1-(naphthalen-1-yl)-N1,N4-diphenylnaphthalene-1,4-diamine (NPNA2) donor and an electron-transporting phosphine oxide (PO) acceptor at different positions of the phenyl bridge have been synthesized. POpN (glass transition temperature Tg = 119 °C) and POmN (Tg = 115 °C) exhibit high morphological stability. Two yellow phosphorescent organic light-emitting diodes (PhOLEDs, ITO (indium tin oxide)/TAPC (1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane, 40 nm)/POpN or POmN: Ir(bt)2(acac) (bis(2-phenylbenzothiozolato-N,C2′)iridium(acetylacetonate), 15 wt%, 20 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm)) exhibit maximum luminances (Lmax) of 82057 and 78385 cd m−2, maximum current efficiencies (ηc,max) of 68.28 and 44.95 cd A−1, respectively, with low efficiency roll-off.
Co-reporter:Ignacio Hernández, You-Xuan Zheng, Majid Motevalli, Rendy H. C. Tan, William P. Gillin and Peter B. Wyatt
Chemical Communications 2013 - vol. 49(Issue 19) pp:NaN1935-1935
Publication Date(Web):2013/01/15
DOI:10.1039/C3CC38610D
New Yb(III) complexes based on the pentachlorotropolonate (pctrop) ligand show enhanced infrared emission when excited in the orange organic chromophore. Yb(pctrop)3(DMF-d7)2 presents the highest reported quantum yield for a nonfluorinated infrared-emitting organolanthanide complex.
Co-reporter:Dong Wang, Qiu-Lei Xu, Song Zhang, Hong-Yan Li, Cheng-Cheng Wang, Tian-Yi Li, Yi-Ming Jing, Wei Huang, You-Xuan Zheng and Gianluca Accorsi
Dalton Transactions 2013 - vol. 42(Issue 8) pp:NaN2723-2723
Publication Date(Web):2012/11/15
DOI:10.1039/C2DT32154H
Based on 2,2′:6′,2′′-terpyridine ligands (L1), five terpyridine derivatives, namely 4′-carbazol-9-yl-2,2′:6′,2′′-terpyridine (L2), 4′-diphenylamino-2,2′:6′,2′′-terpyridine (L3), 4′-bis(4-tert-butylphenyl)amino-2,2′:6′,2′′-terpyridine (L4), 4′-[naphthalen-1-yl-(phenyl)amino]-2,2′:6′,2′′-terpyridine (L5), 4′-[naphthalen-2-yl(phenyl)amino]-2,2′:6′,2′′-terpyridine (L6) and their corresponding Re(I) complexes ReLnnn(CO)33Cl (n = 1–6) have been synthesized and characterized by elemental analysis and 1H NMR spectroscopy. The X-ray crystal structure of ReL3(CO)33Cl has also been obtained. The luminescence spectra of ReL2(CO)33Cl–ReL5(CO)33Cl, obtained in CH2Cl2 solution at room temperature, show strong dπ (Re) → π* (diimine) MLCT character (λmax ∼ 600 nm) and a small red shift relative to ReL1(CO)33Cl. This, confirmed by the study of the triplet energy levels of the L1–L6 ligands at low temperature (77 K rigid matrix), indicates that the introduction of electron-donating moieties on the terpyridine unit decreases the triplet levels of the ligands, leading to a reduction of the energy gap between d and π* orbitals. In the solid state, upon MLCT excitation, all the complexes show an even stronger emission and a blue spectral shift (λmax ∼ 550 nm) compared to those obtained in solution.
Co-reporter:Zheng-Guang Wu, Xiao Liang, Jie Zhou, Lei Yu, Yi Wang, You-Xuan Zheng, Yu-Feng Li, Jing-Lin Zuo and Yi Pan
Chemical Communications 2017 - vol. 53(Issue 49) pp:NaN6640-6640
Publication Date(Web):2017/05/17
DOI:10.1039/C7CC02433A
On account of the broad utilities of organophosphorus compounds, the development of highly efficient and concise phosphination methods is significantly important and urgent. Herein, we disclose a novel method for the synthesis of phosphorylated heterocycles: versatile intermediate propargylamines serving as a new type of radical acceptors incorporated in P-radicals via a photocatalytic strategy. This reaction proceeds through a cascade phosphinoylation/cyclization/oxidation/aromatization pathway using readily available starting materials under mild conditions of light with excellent atom economy, catalyzed by AgOAc or fac-Ir(ppy)3. One of the phosphorylated quinolines was selected, as an example, as an electron-transporting material for fabricating phosphorescence organic light-emitting diodes displaying excellent electroluminescence performances with a maximum external quantum efficiency of 21.9% with negligible efficiency roll-off ratios.
Co-reporter:Qiu-Lei Xu, Xiao Liang, Liang Jiang, Yue Zhao and You-Xuan Zheng
Dalton Transactions 2016 - vol. 45(Issue 17) pp:NaN7372-7372
Publication Date(Web):2016/03/11
DOI:10.1039/C6DT00518G
Three bis-cyclometalated iridium complexes ((TPP)2Ir(acac), (TPP)2Ir(tpip) and (TPP)2Ir(pic)) with 2-(2-trifluoromethyl)pyrimidine-pyridine (TPP) as the main ligand, 2,4-pentanedionate (acac), tetraphenylimidodiphosphinate (tpip) and picolinate (pic) as the ancillary ligands, respectively, were prepared. Their photoluminescence and electrochemistry properties were investigated in detail, and (TPP)2Ir(tpip) was also examined by X-ray crystallography. These complexes show bluish green emission with a quantum efficiency of 11–14%. The organic light emitting diodes (OLEDs) with the structure of ITO/TAPC (1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane, 40 nm)/mCP (1,3-bis(9H-carbazol-9-yl)benzene, 10 nm)/Ir complex (8 wt%):PPO21 (3-(diphenylphosphoryl)-9-(4-(diphenylphosphoryl)phenyl)-9H-carbazole, 25 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 50 nm)/LiF (1 nm)/Al (100 nm) were fabricated to evaluate the potential application of these complexes. A (TPP)2Ir(tpip) emitter based device showed the best performance of a maximum current efficiency (ηc) value of 37.61 cd A−1 and a maximum external quantum efficiency (EQE) of 13.7% with low efficiency roll-off.
Co-reporter:Qiu-Lei Xu, Xiao Liang, Song Zhang, Yi-Ming Jing, Xuan Liu, Guang-Zhao Lu, You-Xuan Zheng and Jing-Lin Zuo
Journal of Materials Chemistry A 2015 - vol. 3(Issue 15) pp:NaN3701-3701
Publication Date(Web):2015/02/18
DOI:10.1039/C5TC00073D
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 as the ancillary ligand were prepared, and their X-ray crystallography, photoluminescence, electrochemistry properties were investigated. The Ir1 and Ir2 complexes show green emissions at about 500 and 502 nm with high quantum efficiencies of 0.63 and 0.93, respectively. Moreover, they also exhibit higher electron mobility than that of Alq3 (tris-(8-hydroxyquinoline)aluminium). The organic light emitting diodes (OLEDs) with the structure of ITO/TAPC (1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane, 40 nm)/mCP (1,3-bis(9H-carbazol-9-yl)benzene, 10 nm)/Ir complex (8 wt%): PPO21 (3-(diphenylphosphoryl)-9-(4-(diphenylphosphoryl)phenyl)-9H-carbazole, 25 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 50 nm)/LiF (1 nm)/Al (100 nm) showed excellent performances, partly due to their high quantum efficiency and high electron mobility. For the devices G1 and G2, the maximum current efficiency (ηc) values are as high as 101.96/99.97 cd A−1 and the maximum external quantum efficiencies of 31.6% and 30.5% with low electroluminescence efficiency roll-off. The ηc data still remain over 90 cd A−1 even at the luminance of 10000 cd m−2, which proves that the complexes have potential applications as efficient green emitters in OLEDs.
Co-reporter:Hong-Yan Li, Tian-Yi Li, Ming-Yu Teng, Qiu-Lei Xu, Song Zhang, Yi-Ming Jin, Xuan Liu, You-Xuan Zheng and Jing-Lin Zuo
Journal of Materials Chemistry A 2014 - vol. 2(Issue 6) pp:NaN1124-1124
Publication Date(Web):2013/11/15
DOI:10.1039/C3TC31915F
Four new iridium(III) cyclometalated complexes (Ir1–Ir4) with 4-trifluoromethylphenylpyridine as the main ligand and 2-(5-phenyl-1,3,4-oxadiazol-2-yl)-phenol and its fluoro/trifluoromethyl substituted derivatives as ancillary ligands have been developed. All complexes are green phosphors (λmax = 519–537 nm) with photoluminescence quantum efficiency yields of 10–53% in CH2Cl2 solutions at room temperature, respectively. The organic light emitting diodes (OLEDs) with the structure of ITO/TAPC (1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane, 60 nm)/Ir complexes (8 wt%):SimCP2 (bis[3,5-di(9H-carbazol-9-yl)phenyl] diphenylsilane, 30 nm)/TPBi (1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl, 90 nm)/LiF (1 nm)/Al (100 nm) show good performances. In particular, device G4 based on complex Ir4 (2-(5-pentafluorophenyl-1,3,4-oxadiazol-2-yl)-phenol as ancillary ligand) showed superior performances with a peak current efficiency (ηc) of 70.48 cd A−1 and a peak external quantum efficiency (ηext, EQE) of 19.7%. This study demonstrates that the ancillary ligand attached with the 1,3,4-oxadiazole group could facilitate charge trapping across the bulk of the device for efficient OLEDs.
Co-reporter:Hong-Yan Li, Liang Zhou, Ming-Yu Teng, Qiu-Lei Xu, Chen Lin, You-Xuan Zheng, Jing-Lin Zuo, Hong-Jie Zhang and Xiao-Zeng You
Journal of Materials Chemistry A 2013 - vol. 1(Issue 3) pp:NaN565-565
Publication Date(Web):2012/10/31
DOI:10.1039/C2TC00052K
A new iridium(III) complex Ir(tfmppy)2(tfmtpip) (1, tfmppy = 4-trifluoromethylphenyl-pyridine, tfmtpip = tetra(4-trifluoromethylphenyl)imidodiphosphinate) was synthesized and applied in organic light-emitting diodes (OLEDs). The devices with the structures of ITO/TAPC (1,1-bis[4-[N,N-di(p-tolyl)amino]phenyl]cyclohexane, 40 nm)/1 (x wt%): mCP (N,N′-dicarbazolyl- 3,5-benzene, 20 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) exhibited a maximum power efficiency (ηp,max) of 113.23 lm W−1 and a maximum current efficiency (ηc,max) of 115.39 cd A−1 (0.01342 mA cm2) at the doping level of 5 wt%, which is among the best performances for Ir(III) complex based OLEDs in the green-light-emitting region. Compared with our former work, the excellent device efficiencies are due to the use of TmPyPB as the electron-transporting/hole-blocking layer which has a relatively higher electron mobility than that of TPBi (2,2′,2′′-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)) and the introduction of the –CF3 moiety to the Ir(III) complex, which can increase the electron mobility of the complex. The device performances proved that the complex has potential applications as an efficient green emitter in OLEDs.
