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Novel hole blocking materials based on 2,6-disubstituted dibenzo[ <i>b</i> , <i>d</i> ]furan and dibenzo[ <i>b</i> , <i>d</i> ]thiophene segments for high-performance blue phosphorescent organic light-emitting diodes
摘要： Novel hole blocking materials (HBMs) based on 2,6-disubstituted dibenzo[b,d]furan and dibenzo[b,d]thiophene segments, 3,30,300,30 0 0-(dibenzo[b,d]furan-2,6-diylbis(benzene-5,3,1-triyl))tetrapyridine (26DBFPTPy) and 3,30,300,30 0 0-(dibenzo[b,d]thiophene-2,6-diylbis(benzene-5,3,1-triyl))tetrapyridine (26DBTPTPy), are successfully designed and synthesized for high-performance blue phosphorescent organic light-emitting diodes (PhOLEDs) for the first time. Computational simulation is used to investigate the optimal structure, orbital distribution, and physicochemical properties of both molecules. Thermal, optical, and electrochemical analysis shows that 26DBFPTPy and 26DBTPTPy possess high thermal stability, deep HOMO energy levels ((cid:2)7.08 and (cid:2)6.91 eV), and a high triplet energy (ET) (2.75 and 2.70 eV). Blue PhOLEDs with 26DBFPTPy or 26DBTPTPy as a hole blocking layer (HBL) exhibit a low turn-on voltage (3.0 V) and operating voltage (4.5 V) at 1000 cd m(cid:2)2. In addition, the blue PhOLEDs with 26DBFPTPy or 26DBTPTPy show superior external quantum e?ciencies (24.1 and 23.6%) and power e?ciencies (43.9 and 42.7 lm W(cid:2)1). They also show a very small e?ciency roll-o? of about 8.5% from 100 to 1000 cd m(cid:2)2. Furthermore, they exhibit improved lifetimes compared to the similarly designed HBL with a pyridine electron transport unit and a phenyl core structure.
关键词： dibenzo[b,d]furan,hole blocking materials,dibenzo[b,d]thiophene,blue phosphorescent organic light-emitting diodes,high-performance
更新于2025-11-14 15:32:45
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Evolution of pure hydrocarbon hosts: simpler structure, higher performance and universal application in RGB phosphorescent organic light-emitting diodes
摘要： In the field of phosphorescent organic light-emitting diodes (PhOLEDs), designing high-efficiency universal host materials for red, green and blue (RGB) phosphors has been quite a challenge. To date, most of the high-efficiency universal hosts reported incorporate heteroatoms, which have a crucial role in the device performance. However, the introduction of different kinds of heterocycles increases the design complexity and cost of the target material and also creates potential instability in the device performance. In this work, we show that pure aromatic hydrocarbon hosts designed with the 9,90-spirobifluorene scaffold are high-efficiency and versatile hosts for PhOLEDs. With external quantum efficiencies of 27.3%, 26.0% and 27.1% for RGB PhOLEDs respectively, this work not only reports the first examples of high-efficiency pure hydrocarbon materials used as hosts in RGB PhOLEDs but also the highest performance reported to date for a universal host (including heteroatom-based hosts). This work shows that the PHC design strategy is promising for the future development of the OLED industry as a high-performance and low-cost option.
关键词： RGB phosphors,PhOLEDs,external quantum efficiencies,phosphorescent organic light-emitting diodes,universal host materials,pure aromatic hydrocarbon hosts,9,90-spirobifluorene scaffold
更新于2025-09-23 15:21:01
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Saturated red phosphorescent Iridium(III) complexes containing phenylquinoline ligands for efficient organic light-emitting diodes
摘要： Saturated red iridium phosphors are strongly desired for application in organic light-emitting diodes (OLEDs). Most of the reported iridium complexes with 2-arylquinoline or its derivatives as cyclometalating ligands are orange-red phosphorescent with peak wavelength below 620 nm. Herein trifluoromethyl (CF3) or Fluorine (F) is introduced into the 6-site of quinoline ring to design and synthesize the cyclometalated ligands 2-phenyl-6-CF3/F-quinoline (CF3-phq or F-phq) and heteroleptic iridium complexes Ir(CF3-phq)2(acac) (Ir-1), Ir(CF3-phq)2(tmd) (Ir-2), Ir(F-phq)2(acac) (Ir-3) and Ir(F-phq)2(tmd) (Ir-4). Owing to the electron-deficient feature of CF3 and F, the electron affinity of these complexes are increased, the corresponding LUMOs are pulled downwards, and the phosphorescence of CF3-containing iridium complexes are saturated red with peaks at 627–632 nm in photoluminescence. At the same time, by varying the ancillary ligand from acetylacetonate (acac) to 2,2,6,6-tetrametylheptane-3,5-dionate (tmd), the emitting performance are dramatically improved. As a result, the Ir(CF3-phq)2(tmd) based red OLED realized pure red electroluminescence with Commision Internationale de L’Eclairage (CIE) coordinates of (0.67, 0.33) with a high brightness of 12695 cd m?2 and a maximum external quantum efficiency of 14.96%, respectively, which maintained as high as 9.62% at a practical luminance of 1000 cd m?2. This is the first example of saturated red iridium phosphors with structure modification at the 6-site of quinoline ring of 2-phenylquinoline ligand.
关键词： Iridium complex,Phosphorescent organic light emitting diodes (PhOLEDs),Saturated red,2-Phenylquinoline,Trifluoromethyl
更新于2025-09-23 15:19:57
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Regioisomer effects of dibenzofuran-based bipolar host materials on yellow phosphorescent OLED device performance
摘要： Four regioisomers were synthesized for use as bipolar host materials for phosphorescent organic light-emitting diodes (PhOLEDs) by classic cross-coupling reactions using cyanofluorene and fused dibenzofuran and were readily purified. To realize the bipolar host material, a cyano-substituted fluorene was selected as the n-type unit and dibenzofuran as the p-type unit. Yellow PhOLEDs were fabricated with iridium(III) bis(4-phenylthieno[3,2-c]pyridinato-N,C20)acetylacetonate [PO-01] as a phosphorescent emitter. The achieved maximum current efficiency was 77.2 cd A?1 and the external quantum efficiency was 25.3% for the [PO-01]-based PhOLED; the 7-(dibenzo[b,d]furan-2-yl)-9,9-dimethyl-9H-fluorene-2-carbonitrile (CF-2-BzF) host had the best device performance. The color coordinates of yellow PhOLEDs at 1000 cd m?2 were (0.50, 0.50) (CF-1-BzF), (0.50, 0.49) (CF-2-BzF), (0.51, 0.49) (CF-3-BzF), and (0.50, 0.50) (CF-4-BzF).
关键词： regioisomer effects,phosphorescent organic light-emitting diodes,device performance,bipolar host materials,yellow PhOLEDs
更新于2025-09-23 15:19:57
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Diphenylamine/triazine hybrids as bipolar hosts for phosphorescent organic light-emitting diodes
摘要： The bipolar host materials employing diphenylamine (DPA) as donor unit and triazine (TRZ) as acceptor unit could achieve suitable energy levels and balanced charge transporting properties, which are necessary for high performance of organic light-emitting diodes (OLEDs). In this work, three DPA/TRZ based host materials, named 2-(4-(N,N-diphenylamino)phenyl)-4,6-diphenyl-1,3,5-triazine (DPA-TRZ), 2,4-bis(4-(N,N-diphenylamino)phenyl)-6-phenyl-1,3,5-triazine (DDPA-TRZ), and 2,4,6-tris(4-(N,N-diphenylamino)phenyl)-1,3,5-triazine (TDPA-TRZ) were designed and synthesized. Their thermal, photophysical, electrochemical, and carrier transporting properties were investigated to reveal the relationship between molecular structure and properties. The number of DPA units could regularly tune the optical and electrical properties of the hybrids. The triplet excited state energy (ET) values of DPA-TRZ, DDPA-TRZ, and TDPA-TRZ are 2.38, 2.51, and 2.73 eV, respectively. To evaluate the electroluminescent properties of the three host materials, blue, green, red, and white phosphorescent OLEDs (PhOLEDs) were fabricated and characterized. With the highest ET value, TDPA-TRZ can afford from blue to red phosphorescent emitters. All these devices exhibited EQEs of over 20% with relatively low efficiency roll-offs. The single-host white PhOLEDs based on TDPA-TRZ showed impressive color stability and superior color rendition. These results demonstrate that the combination of DPA and TRZ is an effective way to construct highly efficient bipolar host materials.
关键词： diphenylamine,triazine,phosphorescent organic light-emitting diodes,charge transporting properties,bipolar host materials
更新于2025-09-23 15:19:57
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Control of ??a???? stacking in carbazole-benzimidazo???1,2- <i>f</i> ???phenanthridines: the design of electron-transporting bipolar hosts for phosphorescent organic light-emitting diodes
摘要： Two bipolar hosts, 8-cbzBIFP and 10-cbzBIFP, both with basic skeletons of orthogonally-connected carbazole and benzimidazoh1,2-fiphenanthridine (BIFP) have been prepared. The planar structure of the BIFP moiety in comparison to the governs the molecular stacking in the crystal lattice. Electron transport properties, benzimidazole derivatives, are facilitated. Both hosts display fabulous performances in phosphorescent organic light-emitting diodes with bis(2-phenylpyridine)(acetylacetonate)iridium(III) as an emitter. The optimized green PhOLED of 10-cbzBIFP achieves the maximum brightness (Lmax) of 58 810 cd m(cid:2)2, the maximum current e?ciency (Zc) of 87.0 cd A(cid:2)1 and external quantum e?ciency (EQE) of 21.1%. Likewise, 8-cbzBIFP shows an Lmax of 58 870 cd m(cid:2)2, Zc of 77.3 cd A(cid:2)1 and EQE of 19.1%.
关键词： electron-transporting,phosphorescent organic light-emitting diodes,carbazole-benzimidazoh1,2-fiphenanthridines,bipolar hosts,p–p stacking
更新于2025-09-23 15:19:57
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A negative polaron resistant p-type host for extended lifetime in deep blue phosphorescent organic light-emitting diodes
摘要： A novel mixed host employing a negative polaron stabilizing p-type host was developed to extend the device lifetime of blue phosphorescent organic light-emitting diodes (PhOLEDs). Instead of a conventional p-type host with only a hole transport unit, a p-type host with a negative polaron resistant unit in addition to the hole transport unit was used in the mixed host consisting of a p-type host and an n-type host. The p-type host had benzonitrile as a negative polaron resistant unit which stabilized the molecule under negative polarons. The use of the p-type host with the benzonitrile unit almost doubled the device lifetime of the blue PhOLEDs due to the improved negative polaron stability of the hosts. Therefore, the p-type host with the weak electron accepting benzonitrile unit can play the role of a lifetime extending p-type host to replace a conventional p-type host.
关键词： p-type host,device lifetime,negative polaron,benzonitrile,blue phosphorescent organic light-emitting diodes
更新于2025-09-23 15:19:57
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Oxadiazole derivatives as bipolar host materials for high-performance blue and green phosphorescent organic light-emitting diodes
摘要： By combining two n-type groups, pyridine and oxadiazole, with one p-type carbazole group, two novel bipolar hosts, namely 2-(3-(9H-carbazol-9-yl)-[1,10-biphenyl]-3-yl)-5-(pyridin-2-yl)-1,3,4-oxadiazole (PyOxd-mCz) and 2-(40-(9H-carbazol-9-yl)-[1,10-biphenyl]-3-yl)-5-(pyridin-2-yl)-1,3,4-oxadiazole (PyOxd-pCz) have been developed as hosts for blue and green phosphorescent organic light-emitting diodes (PhOLEDs). The two compounds exhibit similar HOMO levels of ?5.64 eV for PyOxd-mCz and ?5.63 eV for PyOxd-pCz and the same LUMO level of ?2.60 eV. With a more twisted configuration due to meta connections, PyOxd-mCz possesses a higher triplet energy level (ET = 2.77 eV) and more balanced carrier transport than PyOxd-pCz (ET = 2.60 eV). PyOxd-mCz hosted devices achieve a peak current efficiency of 39.7 cd A?1 and a maximum EQE of 20.8% with a low turn-on voltage of 3.5 V for FIrpic and 55.2 cd A?1 and 16.4% for Ir(ppy)3. Apart from the appropriate frontier molecular orbital levels and sufficiently high triplet energy of PyOxd-mCz, the more balanced carrier transport plays a key role for excellent device performance.
关键词： phosphorescent organic light-emitting diodes,bipolar host materials,blue and green PhOLEDs,PyOxd-mCz,PyOxd-pCz
更新于2025-09-16 10:30:52
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Achieving high-performance phosphorescent organic light-emitting diodes using thermally activated delayed fluorescence with low concentration
摘要： We fabricated phosphorescent organic light-emitting diodes (PhOLEDs) using thermally activated delayed fluorescence (TADF) material 10,10'-(4,4'-sulfonylbis(4,1-phenylene)) bis(9,9-dimethyl-9,10-dihydroacridine) (DMAC-DPS) with low concentration, which showed better performance compared with 1,3-bis(carbazole-9-yl) benzene (mCP) based devices. When the concentration of DMAC-DPS was 1wt%, the driving voltage of the device was only 3.3 V at 1 000 cd/m2, and the efficiency and lifetime of the device were effectively improved compared with those of mCP based devices. The result indicated that DMAC-DPS could effectively improve the performance of phosphorescent devices. We believe that the better device performance can be attributed to the optimization of the energy transfer process in the emitter layer and lifetime of triplet excitons by DMAC-DPS. The study may provide a simple and effective strategy to achieve high-performance OLEDs.
关键词： DMAC-DPS,thermally activated delayed fluorescence,triplet excitons,energy transfer,phosphorescent organic light-emitting diodes
更新于2025-09-16 10:30:52
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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