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Synthesis of Phenylpyridine Iridium(III) Complexes with N-Heterocyclic Carbene as Ancillary Ligands
摘要： In this study, [Ir(2,4-F2ppy)2(2-(1,2,4-triazol-1-yl)pyridine)]PF6 (C1), [Ir(2,4-F2ppy)2(2-(2-(4-dimethylbenzyl)-1,2,4-triazol-1-yl)pyridine)]PF6 (C2) and [Ir(2,4-F2ppy)2(2(2-hexyl-1,2,4-triazol-1-yl)pyridine)]PF6 (C3) complexes were successfully synthesised by refluxing the mixture of dichloro-bridged iridium(III) dimer, [Ir(2,4-F2ppy)2(μ-Cl)]2 and corresponding triazolium salt containing N-heterocyclic carbene (NHC) as ancillary ligands. 1H NMR of all complexes display well-resolved signals between 10.00-5.00 ppm assign to proton at the aromatic region for penylpyridine and pyridyltriazole. Spectra of C2 and C3 also display signals at aliphatic region (singlets) between 0.80-1.50 ppm that proved the presence of methylbenzyl and hexyl substituent on the pyridyltriazole ring. In addition, IR analysis reported the presence of C=C and C=N stretching of pyridine at range 1570-1470cm-1 and C-H stretching of aromatic pyridine at 2990-3080cm-1. Besides, UV-Vis absorption data showed that the low-energy metal-to-ligand charge-transfer (MLCT) band in C2 (364 nm) is significantly blue-shifted compared to C1 (375 nm) and C3 (381 nm). Overall, this study reported the synthesis and spectroscopic study of phenylpyridine Ir(III) complexes with various types of pyridyltriazole (NHC ancillary ligands).
关键词： Phenylpyridine Iridium(III) Complexes,Spectroscopic Study,N-Heterocyclic Carbene,Ancillary Ligands,Synthesis
更新于2025-09-23 15:21:01
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Homoleptic mer-Ir(III) complexes for highly efficient solution-processable green phosphorescent organic light-emitting diodes with high current efficiency
摘要： Two new highly efficient homoleptic green-emitting meridional iridium (III) complexes namely, mer-tris[5-hexyl-8-trifluoromethyl-5H-benzo(c)(1,5)naphthyridin-6-one]iridium(III) (mer-Ir1) and mer-tris[5-ethylhexyl-8-trifluoromethyl-5H-benzo(c)(1,5)naphthyridin-6-one]iridium(III) (mer-Ir2) were designed and synthesized at high temperature. These new Ir(III) complexes consist of amide bridged trifluoromethyl substituted phenylpyridine skeleton with longer alkyl chain. Interestingly, both Ir(III) complexes, mer-Ir1 and mer-Ir2 show bright green emission (λmax = 528 nm) with high photoluminescence quantum yields of 42 and 51% in solution at room temperature, respectively. Their thermal, photophysical, electrochemical, and electroluminescent (EL) properties were fully investigated. Both complexes were used as dopants for solution-processed green phosphorescence organic light-emitting diodes (PHOLEDs). Notably, the device using mer-Ir2 as new green dopant exhibited excellent EL performance with a maximum external quantum efficiency of 20.03% and maximum current efficiency of 67.81 cd A-1. To the best of our knowledge, this is the first time, particularly Ir(C^N)3 based mer-Ir(III) isomers showing excellent EL performance with high luminous efficiency in the green region via solution-processed PHOLEDs has been reported.
关键词： high photoluminescence quantum yields,current efficiency,external quantum efficiency,homoleptic green-emitting meridional iridium (III) complexes,solution-processed green phosphorescence organic light-emitting diodes (PHOLEDs)
更新于2025-09-23 15:19:57
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Investigation on the photophysical properties of a series of promising phosphorescent iridium (III) complexes with modified cyclometalating ligands
摘要： Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were applied to investigate the electronic structures and photophysical properties of a series of phosphorescent iridium (III) complexes, [(C^N)2Ir(N^N)]+(PF6)(cid:2), in which C^N = 4-aryl-1-benzyl-1H-1, 2, 3-triazoles. Herein, aryl = phenyl, biphenyl, three-phenyl aromatic for complexes 1a, 2a, 3a (N^N = 2, 20-bipyridine) and aryl = 40, 60-di?uorophenyl, 60-?uoro-biphenyl, 60-?uoro-three-phenyl aromatic for complexes 1b, 2b, 3b (N^N = 4, 40-di-tert-butyl-2, 20-bipyridine), respectively. The geometric/electronic con?gurations, absorption/emission properties and phosphorescent performances have been outlined for each of the complexes. Based on the two simpli?cations presented in this paper and the available experimental data, the phosphorescent radiative rates for complexes 1a-3b were approximately obtained to be: 1.20 (cid:3) 106 s(cid:2)1, 1.68 (cid:3) 105 s(cid:2)1, 2.19 (cid:3) 107 s(cid:2)1, 3.85 (cid:3) 106 s(cid:2)1, 1.85 (cid:3) 107 s(cid:2)1 and 1.50 (cid:3) 107 s(cid:2)1, respectively. In view of the electroluminescent applications in OLED, our present research work is of great importance for the design and synthesis of organo-transition metal complexes with improved phosphorescent performances.
关键词： Phosphorescence,Photophysical properties,Time-dependent DFT,Iridium (III) complexes,Density functional theory (DFT)
更新于2025-09-19 17:15:36
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Bis-Cyclometalated Iridium Complexes Containing 4,4a?2-Bis(phosphonomethyl)-2,2a?2-bipyridine Ligands: Photophysics, Electrochemistry, and High-Voltage Dye-Sensitized Solar Cells
摘要： In this report, the synthesis and characterization of two bis-cyclometalated iridium(III) complexes are presented. Single-crystal X-ray diffraction shows [Ir(ppy)2(4,4′-bis(diethylphosphonomethyl)-2,2′-bipyridine)]PF6 adopts a pseudo-octahedral geometry. The complexes have an absorption feature in the near-visible?UV region and emit green light with excited-state lifetimes in hundreds of nanoseconds. The redox properties of these complexes show reversible behavior for both oxidative and reductive events. [Ir(ppy)2(4,4′-bis(phosphonomethyl)-2,2′-bipyridine)]PF6 readily binds to metal oxide supports, like nanostructured SnIV-doped In2O3 and TiO2, while still retaining reversible redox chemistry. When incorporated as the photoanode in dye-sensitized solar cells, the devices exhibit open-circuit voltages of >1 V, which is a testament to their strength of these iridium(III) complexes as photochemical oxidants.
关键词： high-voltage,dye-sensitized solar cells,bis-cyclometalated iridium(III) complexes,electrochemistry,photophysics
更新于2025-09-19 17:13:59
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Neutral Cyclometalated Iridium(III) Complexes Bearing Substituted N-Heterocyclic Carbene (NHC) Ligands for High-Performance Yellow OLED Application
摘要： The synthesis, crystal structure, and photophysics of a series of neutral cyclometalated iridium(III) complexes bearing substituted N-heterocyclic carbene (NHC) ancillary ligands ((C∧N)2Ir(R-NHC), where C∧N and NHC refer to the cyclometalating ligand benzo[h]quinoline and 1-phenylbenzimidazole, respectively) are reported. The NHC ligands were substituted with electron-withdrawing or -donating groups on C4′ of the phenyl ring (R = NO2 (Ir1), CN (Ir2), H (Ir3), OCH3 (Ir4), N(CH3)2 (Ir5)) or C5 of the benzimidazole ring (R = NO2 (Ir6), N(CH3)2 (Ir7)). The configuration of Ir1 was confirmed by a single-crystal X-ray diffraction analysis. The ground- and excited-state properties of Ir1?Ir7 were investigated by both spectroscopic methods and time-dependent density functional theory (TDDFT) calculations. All complexes possessed moderately strong structureless absorption bands at ca. 440 nm that originated from the C∧N ligand based 1π,π*/1CT (charge transfer)/1d,d transitions and very weak spin?forbidden 3MLCT (metal-to-ligand charge transfer)/3LLCT (ligand-to-ligand charge transfer) transitions beyond 500 nm. Electron-withdrawing substituents caused a slight blue shift of the 1π,π*/1CT/1d,d band, while electron-donating substituents induced a red shift of this band in comparison to the unsubstituted complex Ir3. Except for the weakly emissive nitro-substituted complexes Ir1 and Ir6 that had much shorter lifetimes (≤160 ns), the other complexes are highly emissive in organic solutions with microsecond lifetimes at ca. 540?550 nm at room temperature, with the emitting states being predominantly assigned to 3π,π*/3MLCT states. Although the effect of the substituents on the emission energy was insignificant, the effects on the emission quantum yields and lifetimes were drastic. All complexes also exhibited broad triplet excited-state absorption at 460?700 nm with similar spectral features, indicating the similar parentage of the lowest triplet excited states. The highly emissive Ir2 was used as a dopant for organic light-emitting diode (OLED) fabrication. The device displayed a yellow emission with a maximum current efficiency (ηc) of 71.29 cd A?1, a maximum luminance (Lmax) of 32747 cd m?2, and a maximum external quantum efficiency (EQE) of 20.6%. These results suggest the potential of utilizing this type of neutral Ir(III) complex as an efficient yellow phosphorescent emitter.
关键词： cyclometalated iridium(III) complexes,phosphorescent emitter,OLED,photophysics,N-heterocyclic carbene (NHC) ligands
更新于2025-09-19 17:13:59
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Aggregation-induced phosphorescence enhancement in deep-red and near-infrared emissive iridium( <scp>iii</scp> ) complexes for solution-processable OLEDs
摘要： To fight against the counteractive triplet–triplet annihilation and vibrational deactivation faced by low band-gap phosphorescent emitters, aggregation-induced phosphorescent enhancement (AIPE)-active deep-red and NIR emissive iridium(III) complexes are designed by suitably anchoring electron-withdrawing substituents such as -phenyl (Ir2), -ethyl ester (Ir3), and -trifluoromethyl (Ir4) groups on the N-coordinating quinoline moiety of a (benzo[b]thiophen-2-yl)quinoline cyclometalated ligand along with ancillary picolinate. The fundamentals of the origin of AIPE on Ir2 and Ir4 and its associated excited-state properties are deeply studied through comparison with unsubstituted Ir1 with the help of density functional theory and single-crystal X-ray diffraction analysis. Most importantly, AIPE-active Ir2 is employed for the development of efficient deep-red and NIR PhOLEDs by hybrid solution-processable methods, in which the AIPE effect of Ir2 reaches a maximum external quantum efficiency (EQE) of 7.29% at high doping ratios.
关键词： near-infrared emissive iridium(III) complexes,deep-red,solution-processable OLEDs,Aggregation-induced phosphorescence enhancement
更新于2025-09-19 17:13:59
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Four-membered red iridium( <scp>iii</scp> ) complexes with Ira??Sa??Ca??S structures for efficient organic light-emitting diodes
摘要： Three sulfur atom contained ligands (diphenylcarbamodithioate (dpdtc), di-p-tolylcarbamodithioate (medtc) and bis(4-(trifluoromethyl)phenyl)carbamodithioate (cf3dtc)) were prepared for three red iridium(III) complexes. All (tfmpqz)2Ir(dpdtc), (tfmpqz)2Ir(medtc) and (tfmpqz)2Ir(cf3dtc) complexes were synthesized rapidly at room temperature in 5 min with high yields owing to strong coordination ability between sulfur and iridium atoms, in which 4-(4-(trifluoromethyl)phenyl)quinazoline (tfmpqz) was used as main ligand. Three Ir(III) complexes show distinct PL emissions at the range of 617 - 629 nm with high phosphorescence quantum yields up to of 83%, respectively. With these complexes as dopants, the organic light-emitting devices (OLEDs) with the double-emissive-layer structure of ITO/ HATCN (hexaazatriphenylenehexacabonitrile, 5 nm)/ TAPC ((bis(4-(N,N-ditolylamino)phenyl)cyclohexane, 30 nm)/ Ir(III) complexes: TCTA (4,4',4''-tris(carbazol-9-yl)-triphenylamine) (12 wt%, 10 nm)/ Ir(III) complexes: 26DCzppy (2,6-bis-(3-(carbazol-9-yl)phenyl)pyridine) (12 wt%, 10 nm)/ TmPyPB (1,3,5-tri((3-pyridyl)-phen-3-yl)benzene, 30 nm)/ LiF (1 nm)/ Al (100 nm) achieved good performances. In particular, the device employing (tfmpqz)2Ir(cf3dtc) complex exhibits the champion performances with a maximum luminance of 30 740 cd m-2 and a maximum external quantum efficiency of 26.10%, respectively.
关键词： phosphorescence quantum yields,sulfur atom,iridium(III) complexes,external quantum efficiency,OLEDs
更新于2025-09-19 17:13:59
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Investigation on voltage loss in organic triplet photovoltaic devices based on Ir complexes
摘要： Voltage losses in singlet material-based organic photovoltaic devices (OPVs) have been intensively studied, whereas, only a few investigations on triplet material-based OPVs (T-OPVs) are reported. To investigate the voltage loss in T-OPVs, two homoleptic iridium(III) complexes based on extended p-conjugated benzo[g]phthalazine ligands, Ir(Ftbpa)3 and Ir(FOtbpa)3, are synthesized as sole electron donors. T-OPVs are fabricated by mixing two donors with phenyl-C71-butyric acid methyl ester (PC71BM) as an electron acceptor. Insertion of oxygen-bridges as flexible inert d-spacers in Ir(FOtbpa)3 has slightly elevated both the lowest unoccupied molecular orbital and the highest occupied molecular orbital levels compared to those of Ir(Ftbpa)3, which results in a lower charge transfer (CT) state energy (ECT) for Ir(FOtbpa)3-based devices. However, a higher Voc (0.88 V) is observed for Ir(FOtbpa)3-based devices than those of Ir(Ftbpa)3 (0.80 V). To understand the above result, the morphologies of the two blend films are studied, which excludes the influence of morphology. Furthermore, radiative and non-radiative recombination in two devices is quantitatively investigated, which suggests that a higher Voc can be attributed to reduced radiative and non-radiative recombination loss for the Ir(FOtbpa)3-based devices.
关键词： charge transfer state energy,organic photovoltaic devices,triplet material-based OPVs,radiative and non-radiative recombination,iridium(III) complexes,voltage loss
更新于2025-09-12 10:27:22
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Deep Red Iridium(III) Complexes Based on Pyrene-Substituted Quinoxaline Ligands for Solution-Processed Phosphorescent Organic Light-Emitting Diodes
摘要： In this paper, we systemically investigated the photoelectric properties of three new deep-red quinoxaline-based iridium(III) complexes: Ir-0, Ir-1, and Ir-2. (MPQ)2Ir(dpm) (Ir-0) bore a 2-methyl-3-phenyl-quinoxaline cyclometalated ligand, while (c-PyMPQ)2Ir(dpm) (Ir-1) and (t-PyMPQ)2Ir(dpm) (Ir-2) possessed a 1-pyrene substituent that connected at the 6/7 position of the corresponding ligands. The configurations of the latter two complexes were well-confirmed by single-crystal X-ray diffraction, and both of them had large dihedral angles between the quinoxaline and pyrene units, preventing the emission peaks of the three complexes from being altered too much. Based on the density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations, we concluded that the emission of all complexes originated predominantly from the triplet metal-to-ligand/intraligand charge transfer (3MLCT/3ILCT) state of the non-pyrene-substituted counterpart Ir-0 core. Interestingly, we also obtained another type of pyrene-stacking characteristic crystal of Ir-1, which had an emission resembled the phosphorescence observed in thin film. The easily formed pyrene-stacking configuration would most probably limit their device performance at a higher concentration. Moreover, the fabricated organic light-emitting diodes (OLEDs) using these materials achieved considerable device performance at a low doping concentration of 0.5 wt %. This work provides an approach for reasonably designing large fused-ring-substituted quinoxaline ligands of iridium complexes.
关键词： Pyrene-Substituted Quinoxaline Ligands,Deep Red Iridium(III) Complexes,Solution-Processed Phosphorescent Organic Light-Emitting Diodes
更新于2025-09-12 10:27:22
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Excited-State Switching between Ligand-Centered and Charge Transfer Modulated by Metal–Carbon Bonds in Cyclopentadienyl Iridium Complexes
摘要： Three series of pentamethylcyclopentadienyl (Cp*) Ir(III) complexes with different bidentate ligands were synthesized and structurally characterized, [Cp*Ir(tpy)L]n+ (tpy = 2-tolylpyridinato; n = 0 or 1), [Cp*Ir(piq)L]n+ (piq = 1-phenylisoquinolinato; n = 0 or 1), and [Cp*Ir(bpy)L]m+ (bpy = 2,2′-bipyridine; m = 1 or 2), featuring a range of monodentate carbon-donor ligands within each series [L = 2,6-dimethylphenylisocyanide; 3,5-dimethylimidazol-2-ylidene (NHC); methyl)]. The spectroscopic and photophysical properties of these molecules and those of the photocatalyst [Cp*Ir(bpy)H]+ were examined to establish electronic structure?photophysical property relationships that engender productive photochemical reactivity of this hydride and its methyl analogue. The Ir(III) chromophores containing ancillary CNAr ligands exhibited features anticipated for predominantly ligand-centered (LC) excited states, and analogues bearing the NHC ancillary exhibited properties consistent with LC excited states containing a small admixture of metal-to-ligand charge-transfer (MLCT) character. However, the molecules featuring anionic and strongly σ-donating methyl or hydride ligands exhibited photophysical properties consistent with a high degree of CT character. Density functional theory calculations suggest that the lowest energy triplet states in these complexes are composed of a mixture of MLCT and ligand-to-ligand CT originating from both the Cp* and methyl or hydride ancillary ligands. The high degree of CT character in the triplet excited states of methyliridium complexes bearing C^N-cyclometalated ligands offer a striking contrast to the photophysical properties of pseudo-octahedral structures fac-Ir(C^N)3 or Ir(C^N)2(acac) that have lowest-energy triplet excited states characterized as primarily LC character with a more moderate MLCT admixture.
关键词： cyclopentadienyl iridium complexes,charge transfer,photophysical properties,Iridium(III) complexes,ligand-centered excited states
更新于2025-09-09 09:28:46