Pure Red Iridium(III) Complexes Possessing Good Electron Mobility with 1,5-Naphthyridin-4-ol Derivatives for High-Performance OLEDs with an EQE over 31.

Three iridium(III) complexes (Ir(4tfmpq)2mND, Ir(4tfmpq)2mmND, and Ir(4tfmpq)2mpND) with the 4-(4-(trifluoromethyl)phenyl)quinazoline (4tfmpq) main ligand and 1,5-naphthyridin-4-ol derivatives (mND: 8-methyl-1,5-naphthyridin-4-ol, mmND: 2,8-dimethyl-1,5-naphthyridin-4-ol, mpND: 8-methyl-2-phenyl-1,5-naphthyridin-4-ol) as ancillary ligands were studied. The complexes (Ir(4tfmpq)2mND, Ir(4tfmpq)2mmND, and Ir(4tfmpq)2mpND) emit pure red emissions of 626-630 nm with high photoluminescence quantum yields of 85.2-93.4% in CH2Cl2 and better electron mobilities than that of tri(8-hydroxyquinoline)aluminum. By employing three pure red emitters, all the phosphorescent organic light-emitting diodes exhibited superior performances with a maximum external quantum efficiency of 31.48% and the efficiency roll-off is very mild, which are among the best results ever reported for pure red organic light-emitting diodes using Ir(III) complexes. In addition, CIE( x, y) coordinates of (0.670, 0.327) are also close to the standard red emission required by the National Television System Committee.

Rapid room temperature synthesis of red iridium(iii) complexes containing a four-membered Ir-S-C-S chelating ring for highly efficient OLEDs with EQE over 30.

Three red cyclometalated iridium(iii) complexes (4tfmpq)2Ir(dipdtc), (4tfmpq)2Ir(dpdtc) and (4tfmpq)2Ir(Czdtc) (4tfmpq = 4-(4-(trifluoromethyl)phenyl)quinazoline, dipdtc = N,N-diisopropyl dithiocarbamate, dpdtc = N,N-diphenyl dithiocarbamate, and Czdtc = N-carbazolyl dithiocarbamate) containing the unique four-membered Ir-S-C-S backbone ring were synthesized in five minutes at room temperature with good yields, and the Gibbs free energy calculation results indicate that all reactions are exothermic and thermodynamically favorable processes. The emission colors (λ peak = 641-611 nm), photoluminescence quantum efficiencies (Φ P = 58.3-93.0%) and bipolar properties can be effectively regulated by introducing different electron-donating substituents into the dithiocarbamate ancillary ligands. Employing these emitters, organic light emitting diodes (OLEDs) with double emissive layers exhibit excellent performances with a maximum brightness over 60 000 cd m-2, a maximum current efficiency of 40.68 cd A-1, a maximum external quantum efficiency (EQEmax) of 30.54%, and an EQE of 26.79% at the practical luminance of 1000 cd m-2. These results demonstrate that Ir(iii) complexes with sulfur-containing ligands can be rapidly synthesized at room temperature, which is key to the production of metal luminescent materials for large-scale application in highly efficient OLEDs.

Two platinum(ii) complexes with a 4-phenyl-4H-1,2,4-triazole derivative as an ancillary ligand for efficient green OLEDs.

Two new cyclometalated platinum(ii) complexes ((TN3T)Pt(dptp), (4tfmppy)Pt(dptp)) with 2',6'-bis(trifluoromethyl)-2,3'-bipyridine (TN3T) and 4-trifluoromethylphenylpyridine (4tfmppy) as the cyclometalated ligands and the nitrogen heterocycle 2-(4,5-diphenyl-4H-1,2,4-triazol-3-yl)phenol (dptp) as the ancillary ligand were developed. Both complexes are green phosphors with high photoluminescence quantum efficiency yields (λmax = 532 nm, Φp = 65% for (TN3T)Pt(dptp) and λmax = 502 nm, Φp = 71% for (4tfmppy)Pt(dptp)) in CH2Cl2 solutions at room temperature, respectively. Organic light-emitting diodes (OLEDs) with single-emitting layer and double-emitting layer structures were fabricated with good performances. Particularly, the double-emitting layer device D2 based on the complex (4tfmppy)Pt(dptp) with 6 wt% doped concentration shows superior performances with a maximum EQE of 26.90% with mild efficiency roll-off. This study demonstrates that the ancillary ligand attached with a 4-phenyl-4H-1,2,4-triazole group could facilitate charge trapping across the bulk of the device for efficient OLEDs.

Correction: Rapid room temperature synthesis of red iridium(iii) complexes containing a four-membered Ir-S-C-S chelating ring for highly efficient OLEDs with EQE over 30.

[This corrects the article DOI: 10.1039/C8SC05605F.].

Efficient orange-red electroluminescence of iridium complexes with 1-(2,6-bis(trifluoromethyl)pyridin-4-yl)isoquinoline and 4-(2,6-bis(trifluoromethyl)pyridin-4-yl)quinazoline ligands.

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.

Novel Design of Iridium Phosphors with Pyridinylphosphinate Ligands for High-Efficiency Blue Organic Light-emitting Diodes.

Due to the high quantum efficiency and wide scope of emission colors, iridium (Ir) (III) complexes have been widely applied as guest materials for OLEDs (organic light-emitting diodes). Contrary to well-developed Ir(III)-based red and green phosphorescent complexes, the efficient blue emitters are rare reported. Like the development of the LED, the absence of efficient and stable blue materials hinders the widely practical application of the OLEDs. Inspired by this, we designed two novel ancillary ligands of phenyl(pyridin-2-yl)phosphinate (ppp) and dipyridinylphosphinate (dpp) for efficient blue phosphorescent iridium complexes (dfppy)2Ir(ppp) and (dfppy)2Ir(dpp) (dfppy = 2-(2,4-difluorophenyl)pyridine) with good electron transport property. The devices using the new iridium phosphors display excellent electroluminescence (EL) performances with a peak current efficiency of 58.78 cd/A, a maximum external quantum efficiency of 28.3%, a peak power efficiency of 52.74 lm/W and negligible efficiency roll-off ratios. The results demonstrated that iridium complexes with pyridinylphosphinate ligands are potential blue phosphorescent materials for OLEDs.

Syntheses, photoluminescence and electroluminescence of two novel platinum(ii) complexes.

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.

N-Heterocyclic carbenes: versatile second cyclometalated ligands for neutral iridium(III) heteroleptic complexes.

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.

[Investigation of organophosphorous insecticides residue in Chinese crude drugs].

OBJECTIVE: To study eleven organophosphorus insecticides residuals in four kinds of Chinese crude drugs. METHOD: The organophosphorus insecticides were extracted with dichloromethane and cleaned-up with a mixture of Celite 545-activated carbon. The extracts were analyzed by gas chromatography equipped with a flame photometric detector (FPD). RESULT: Analysis of fortified Chinese crude drug showed that the average recoveries ranged from 77.5% -112.3% at three different levels, the RSDs were below 10% (n = 4). Trace organophosphorous pesticide residues were found in samples of Rhizoma Atractylodis Macrocephalae and Flos Chrysanthemi. CONCLUSION: A method was established for determination multi-residues in Rhizma Atractylodis Macrocephalae, Radix Curcumae, Bulbus Fritillariae Thunbergii and Flos Chrysanthemi. It provides a method for the risk assessment of organophosphorous pesticide in Chinese crude drugs.