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850 nm Pure Near-Infrared Emitting Iridium Complex for Solution-processed Organic Light-Emitting Diodes
摘要： High-performance pure near-infrared organic light-emitting materials and devices with full emission over 700 nm are still rare, though urgently needed. Iridium(III) complexes have been proven to be an important class of NIR emitters. Herein, we report a new NIR homoleptic Ir(III) complex, tris[1,4-di(5-n-octylthiophen-2-yl)benzo[g]phthalazine] iridium(III) (Ir(dotbpa)3), with full emission beyond 700 nm and Iridium mass content as low as 10 wt%. Thanks to the introduction of flexible n-octyl groups, Ir(dotbpa)3 shows greatly improved solubility and excellent solution-processability in comparison with its counterpart Ir(dtbpa)3. By employing a multifunctional host, solution-processed NIR-OLEDs were fabricated with a simple structure of only three organic layers and demonstrated pure NIR emission starting from 725 nm and peaking at 850 nm with maximum external quantum efficiency of 0.17%, which is the first example to achieve pure NIR-OLEDs based on Ir(III) emitters.
关键词： Pure NIR emission,Near-infrared,Solution-processed,Iridium(III) complex,Organic light-emitting diodes
更新于2025-09-23 15:21:01
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Synergetic interface and morphology modification to achieve highly efficient solution-processed sky-blue organic light-emitting diodes
摘要： Solution-processed organic light-emitting diodes (OLEDs), especially blue OLEDs, generally suffer from the low efficiency. Herein, we report an efficient approach to achieve high efficiency by synergetic interface and morphology modification with a polymer, Poly(9-vinylcarbazole) (PVK). Sky-blue thermally activated delayed fluorescent (TADF) material, 10-(4-(4,6-diphenyl-1,3,5- triazin-2-yl)phenyl)-10H- spiro[acridine-9,9-fluorene] (SpiroAC-TRZ), is used as the emitter. The incorporation of PVK thin layer at the hole injection layer/emission layer (EML) interface and a small amount of PVK inner the EML modify the carrier behaviors at the interface and improve the EML morphology. As a result, balanced carrier distribution and reduced carrier recombination are realized at the interface and inner the EML. Through these strategies, the maximum external quantum efficiency and current efficiency of the optimal OLED achieve 25.1% and 53.5 cd/A. To the best of our knowledge, the efficiencies are the highest values ever achieved by the solution-processed sky-blue TADF OLEDs.
关键词： Blue organic light-emitting diodes,Thermally activated delayed fluorescence,High efficiency,All-solution process,Film morphology
更新于2025-09-23 15:21:01
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Highly Efficient Tandem White OLED Using a Hollow Structure
摘要： A simple fabrication method for a light extraction layer is required. In this report, an internal light extraction layer composed of a high refractive index material and an air void is fabricated in five steps. A direct printing process followed by annealing of the randomly arrayed poly(benzyl methacrylate) pillars after a planarization process using TiO2-nanoparticle dispersed resist and sol is used. These substrates are used for light extraction in white tandem organic light emitting diodes (WOLEDs). By combining the hollow structure and hemi-spherical lens, WOLEDs without and with the light extraction structures are found to show maximum external quantum efficiencies of 35.6% and 103%, respectively. The power efficiencies at 100 cd m?2 of the WOLEDs without and with the light extraction structures are found to be 26.5 and 93.2 lm W?1, respectively. A color rendering index of 86.4, correlated color temperature of 4860 K, and CIE of (0.353, 0.389) are achieved in the WOLEDs with light extraction structures.
关键词： organic light emitting diodes,high refractive index,light extraction efficiency,nanoimprint lithography,light scattering layers
更新于2025-09-23 15:19:57
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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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Heavy Atom Effect of Selenium for Metal-Free Phosphorescent Light-Emitting Diodes
摘要： Room-temperature phosphorescence from metal-free purely organic molecules has recently gained much interest. We devised metal-free organic phosphors by incorporating selenium (Se) to promote spin?orbit coupling by its nonmetal heavy atom effect. The Se-based organic phosphors showed bright phosphorescent emission in organic light-emitting diodes (OLEDs) and photo-excited phosphorescence in an amorphous film state. Large orbital angular momentum change (ΔL) during the electron transition process and heavy atom effect of Se render a PL quantum yield of 0.33 ± 0.01 and a high external quantum efficiency (EQE) of 10.7 ± 0.14% in phosphorescent LEDs. This work demonstrates the rational molecular design of metal-free organic phosphorescent emitters with Se as an alternative novel class of materials to the conventional organometallic phosphors for OLEDs.
关键词： organic light-emitting diodes,spin?orbit coupling,selenium,metal-free organic phosphors,phosphorescent LEDs,room-temperature phosphorescence
更新于2025-09-23 15:19:57
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Aromatic imide/amide-based organic small-molecule emitters for organic light-emitting diodes
摘要： Organic electroluminescence materials play an important role in improving the optoelectronic performance of organic light-emitting diodes (OLEDs). Aromatic imide/amide-based organic small-molecule emitters have caught increasing attention due to their unique properties, such as strong electron-withdrawing characteristics, rigid structures and high-fluorescence quantum yields. In recent years, aromatic imide/amide semiconductors have been developed rapidly, but few reviews have been specially reported on their application in OLEDs. This study classified aromatic imides/amides into maleimide (MAI), phthalimide (PHI), naphthalimide (NAI), perylenediimide (PDI), and other imide/amide units according to the chemical structure to summarize the advances of imide/amide-based organic small-molecule emitters from the perspective of device performance and molecular design rules over the past 20 years. The luminescent mechanism was also explored. The findings of this study might provide a constructive guide towards future exploration and promote the further development of innovative imide/amide-based emitters.
关键词： Aromatic imides/amides,organic small-molecule emitters,device performance,organic light-emitting diodes,molecular design
更新于2025-09-23 15:19:57
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Visible light communication with efficient far-red/near-infrared polymer light-emitting diodes
摘要： Visible light communication (VLC) is a wireless technology that relies on optical intensity modulation and is potentially a game changer for internet-of-things (IoT) connectivity. However, VLC is hindered by the low penetration depth of visible light in non-transparent media. One solution is to extend operation into the “nearly (in)visible” near-infrared (NIR, 700–1000 nm) region, thus also enabling VLC in photonic bio-applications, considering the biological tissue NIR semitransparency, while conveniently retaining vestigial red emission to help check the link operativity by simple eye inspection. Here, we report new far-red/NIR organic light-emitting diodes (OLEDs) with a 650–800 nm emission range and external quantum efficiencies among the highest reported in this spectral range (>2.7%, with maximum radiance and luminance of 3.5 mW/cm2 and 260 cd/m2, respectively). With these OLEDs, we then demonstrate a “real-time” VLC setup achieving a data rate of 2.2 Mb/s, which satisfies the requirements for IoT and biosensing applications. These are the highest rates ever reported for an online unequalised VLC link based on solution-processed OLEDs.
关键词： Visible light communication,IoT,VLC,near-infrared,NIR,organic light-emitting diodes,internet-of-things,biosensing,OLEDs
更新于2025-09-23 15:19:57
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Perdeuterated conjugated polymers for ultralowa??frequency magnetic resonance of OLEDs
摘要： Formation of excitons in OLEDs is spin dependent and can be controlled by electron-paramagnetic resonance, affecting device resistance and electroluminescence yield. We explore electrically detected magnetic resonance in the regime of very low magnetic fields (<1mT). A pronounced feature emerges at zero field in addition to the conventional spin-? Zeeman resonance for which the Larmor frequency matches that of the incident radiation. By comparing a conventional π-conjugated polymer as the active material to a perdeuterated analogue, we demonstrate the interplay between zero-field feature and local hyperfine fields. The zero-field peak results from a quasistatic magnetic-field effect of the RF radiation for periods comparable to the carrier-pair lifetime. Zeeman resonances are resolved down to 3.2MHz, approximately twice the Larmor frequency of an electron in Earth’s field. However, since reducing hyperfine fields sharpens the Zeeman peak at the cost of an increased zero-field peak, we suggest that this result constitutes a fundamental low-field limit of magnetic resonance in carrier-pair-based systems. OLEDs offer an alternative solid-state platform to investigate the radical-pair mechanism of magnetic-field effects in photochemical reactions, allowing models of biological magnetoreception to be explored by measuring spin decoherence directly in the time domain.
关键词： Deuteration,Magnetic resonance,Isotopes,Conjugated Polymers,Organic light-emitting diodes
更新于2025-09-23 15:19:57
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High voltage vacuum-processed perovskite solar cells with organic semiconducting interlayers
摘要： In perovskite solar cells, the choice of appropriate transport layers and electrodes is of great importance to guarantee efficient charge transport and collection, minimizing recombination losses. The possibility to sequentially process multiple layers by vacuum methods offers a tool to explore the effects of different materials and their combinations on the performance of optoelectronic devices. In this work, the effect of introducing interlayers and altering the electrode work function has been evaluated in fully vacuum-deposited perovskite solar cells. We compared the performance of solar cells employing common electron buffer layers such as bathocuproine (BCP), with other injection materials used in organic light-emitting diodes, such as lithium quinolate (Liq), as well as their combination. Additionally, high voltage solar cells were obtained using low work function metal electrodes, although with compromised stability. Solar cells with enhanced photovoltage and stability under continuous operation were obtained using BCP and BCP/Liq interlayers, resulting in an efficiency of approximately 19%, which is remarkable for simple methylammonium lead iodide absorbers.
关键词： stability,perovskite solar cells,bathocuproine,interlayers,electron buffer layers,photovoltage,vacuum-deposited,organic light-emitting diodes,lithium quinolate
更新于2025-09-23 15:19:57
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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