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Recent progress in phosphorescent Ir(III) complexes for nondoped organic light-emitting diodes
摘要： Highly efficient phosphorescent organic light-emitting diodes (PHOLEDs) with simple configuration as well as low cost fabrication process have attracted much interest for both academic researches and commercial endeavors. This review provides an update on recent advances in the development Ir(III) complexes and their applications in nondoped PHOLEDs fabricated by both vacuum deposition and solution-processed approaches. The modification of chemical structures of the small molecular Ir(III) complexes and dendrimers through incorporating multiple functional moieties could effectively adjust the optical and electronic characters. These complexes typically possess reduced intermolecular aggregation, various hole and electron transporting abilities so that high-performance nondoped PHOLEDs can be developed. The corresponding structural, optical, electronic, photophysical as well as the EL properties in different colors over the whole spectral region are surveyed and highlighted. In the end, the perspectives of the development for the further trend are presented, hopefully to provide useful guidance for the research on highly efficient Ir(III) complexes and corresponding nondoped PHOLEDs.
关键词： Organic light-emitting diode,Ir(III) complex,Nondoped devices,Phosphorescence
更新于2025-09-23 15:19:57
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Efficient near ultraviolet organic light-emitting diode based on PVK material doped with BCPO molecules
摘要： Near ultraviolet organic light-emitting diodes (NUV-OLEDs) have a wide range of applications. However, when large band-gap polymer of PVK was used as the emitting material, its poor electron transportation capability resulted in a large amount of charge accumulation on both sides of light-emitting layer/electron-transporting layer interface of the device, hence generating intense electroplex emission and seriously reducing the e?ciency of NUV light-emitting. In order to solve this issue, BCPO molecules were doped in PVK with certain concentrations, forming PVK:BCPO mixing light-emitting layers. As compared with pure PVK, electron transportation capability was apparently increased in PVK:BCPO mixing layers. On one hand, charge accumulation at the interface was substantially weakened, and the electroplex emission was inhibited. On the other hand, transportations of electron and hole carriers became more balanced in light-emitting layer. Both of these improvements e?ectively promoted device performance. At appropriate BCPO doping concentration, the external quantum e?ciency of PVK:BCPO-based NUV-OLEDs reached the maximum value of ～2.6 %. Further experimental progress would bring it closer to the practical application in future.
关键词： Electroplex,Near ultraviolet,E?ciency,Organic light-emitting diode
更新于2025-09-23 15:19:57
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Diboron-Based Delayed Fluorescent Emitters with Orange-to-Red Emission and Superior Organic Light-Emitting Diode Efficiency
摘要： For the application of OLEDs in lighting and panels, the basic requirement is to include a full spectrum color range. Compared with the development of blue and green luminophores in thermally activated delayed fluorescence (TADF) technology, the progress of orange-to-red materials is slow and needs further investigation. In this study, three diboron compound-based materials, dPhADBA, dmAcDBA, and SpAcDBA, were designed and synthesized by nucleophilic arylation of three amine donors on 9,10-diboraanthracene (DBA) in a two-step reaction. With increasing electron-donating ability, they show orange-to-red emission with TADF characteristics. The electroluminescence (EL) of these diboron compounds exhibits emissions λmax at 613, 583, and 567 nm, for dPhADBA, dmAcDBA, and SpAcDBA, respectively. It is noteworthy that the rod-like D-A-D structures can achieve high horizontal ratios (84~86%) and outstanding device performance for orange-to-red TADF OLEDs: the highest external quantum efficiencies (ηEQE) for dPhADBA, dmAcDBA, and SpAcDBA are 11.1 ± 0.5%, 24.9 ± 0.5%, and 30.0 ± 0.8%, respectively. Therefore, these diboron-based molecules offer a promising avenue for the design of orange-to-red TADF emitters and the development of highly efficient orange-to-red OLEDs.
关键词： thermally activated delayed fluorescence,9,10-diboraanthracene,horizontal dipole ratio,diboron compound,orange-red color,organic light-emitting diode
更新于2025-09-23 15:19:57
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Stereoregular polymers with pendant carbazolyl groups: Synthesis, properties and optoelectronic applications
摘要： The most recent results concerning the stereospecific synthesis and the microstructural, chemico-physical and optical characterization of polymers containing pendant carbazolyl groups are reviewed for the first time. Stereoregular poly(N-alkenyl-carbazole)s, poly(4-(Ncarbazolyl) methyl styrene), poly(ω-(N-carbazolyl)alkyl acrylate)s and poly(ω-(N-carbazolyl)alkyl metacrylate)s are considered in this review, with a particular focus on the influence of polymer stereochemistry on photophysical behavior. Potential applications of these materials in light-emitting diodes (LEDs), electrochromic devices, electrophotography and holographic memories are also discussed. Among these, we show the appealing results of our experiments, concerning the color tuning in organic LEDs based on poly(N-pentenyl-carbazole) by means of the polymer chain stereoregularity.
关键词： Organic light emitting diode,Carbazole,Optical properties,Stereospecific polymerization
更新于2025-09-23 15:19:57
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24.3: <i>Invited Paper:</i> Printed Electrodes for All‐Solution‐Processed Inverted‐Structure OLEDs
摘要： A key enabling technology for all-printed organic light-emitting diodes is printing electrodes that can be used for anodes or cathodes for conventional or inverted device structures. In both device structures, the first bottom electrodes, which are either transparent or opaque depending on the device structure, are typically printed while the last top electrodes have been deposited by using a vacuum-based evaporation process because when the last top electrodes are fabricated by using a solution-based process, under organic layers are easily damaged during the fabrication process. Although so-called transfer printing process has been often reported for organic devices such as organic solar cells, it has been rarely applied for OLEDs. In addition, no fine patterning has been adopted in such printing processes. As part of our efforts towards all-printed OLEDs, inkjet-printed and/or transfer-printed, finely-patterned PEDOT:PSS electrodes have been investigated in our lab and most recent achievement will be reported in detail. In order to implement all-solution-processed OLEDs, we also studied the inverted-structure OLEDs, which showed comparable results to the conventional structure OLEDs with the vacuum-based deposited electrodes.
关键词： inverted structure,Organic light-emitting diode,OLED,PLED,inkjet-printing,transfer-printing,polymer light-emitting diode
更新于2025-09-19 17:13:59
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Spirobifluorene-based oligopyridine derivatives as electron-transporting materials for green phosphorescent organic light-emitting diodes
摘要： The electron-transporting materials (ETMs), 2,7-bis(3,5-di(pyridin-3-yl)phenyl)-9,9'-spirobi[fluorene] (3-4PySF) and 2,7-bis(3,5-di(pyridin-4-yl)phenyl)-9,9'-spirobi[fluorene] (4-4PySF) were designed and synthesized by combining spirobifluorene moiety with di(pyridine-3-yl)phenyl and di(pyridine-4-yl)phenyl, respectively. The spirobifluorene moiety improves materials’ rigid twisted structure to ensure the morphological stability of amorphous film, and pyridine acts as electron acceptor to enhance electron-transporting ability of materials. The dependence of electron-transporting property on the position of substituted pyridine rings was studied. The melting point (Tm) of 4-4PySF is estimated to be 41 ℃ higher than that of 3-4PySF. And the higher current density in the electron only devices exhibited by 4-4PySF revealed the effect of nitrogen atom position on the charge-transporting properties. Green PhOLEDs based on bis(2-phenylpyridine)iridium(III)(2,2,6,6-tetramethylheptane-3,5-diketonate) (Ir(ppy)2tmd) as the emitter and 3-4PySF, 4-4PySF and 1,3,5-tris(N-phenylbenzimidazol-2-yl-benzene (TPBi) as ETMs were fabricated. Compared to the device based on the conventional ETM TPBi, the devices based on new ETMs exhibited a higher maximum external quantum efficiency (EQE) of 20.5% and a lower turn-on voltage (Von) of 2.6 V.
关键词： electron-transporting material,intermolecular interaction,oligopyridine,organic light-emitting diode,spirobifluorene
更新于2025-09-19 17:13:59
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Green-synthesized, low-cost tetracyanodiazafluorene (TCAF) as electron injection material for organic light-emitting diodes
摘要： Two electron-deficient azaacenes including di- and tetra-cyanodiazafluorene (DCAF and TCAF) with the advantages of deep lowest unoccupied molecular orbital (LUMO), green-synthesis, low-cost, simply purification method, excellent yields have been obtained, characterized and used as electron injection materials (EIMs) in three groups of electroluminescence devices. Device B with TCAF as EIM exhibited the best performance including turn-on voltage of 5.0 V, stronger maximum luminance intensity of 31,549 cd/m2, higher luminance efficiency of 62.34 cd/A and larger power efficiency of 21.74 lm/W which are 0.53, 6.7, 9.3 and 15.3 times than that of device A with DCAF as EIMs, respectively. The enhanced interfacial electron injection ability of TCAF than that of DCAF is supported by its better electron mobility in electron-only device, deeper LUMO (-4.52 eV), and stronger electronic affinity. Best external quantum efficiency of 16.56% was achieved with optimized thicknesses of TCAF as EIM and TPBi as electron transporting layer. As a new comer of acceptor family, TCAF would push forward organic electronics with more fascinating and significant applications.
关键词： Tetracyanodiazafluorene (TCAF),Organic light-emitting diode,Green-synthesis,Electron-injection material,Acceptor
更新于2025-09-19 17:13:59
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Angular-Fused Dithianaphthylquinone Derivative: Selective Synthesis, Thermally Activated Delayed Fluorescence Property, and Application in Organic Light-Emitting Diode
摘要： A novel angular-fused dithianaphthylquinone derivative, f-TX-TPA, was designed and selectively synthesized. The regioselectivity of angular-fused reaction was interpreted by theoretical calculations. The f-TX-TPA compound displayed excellent thermally activated delayed ?uorescence property. Moreover, the organic light-emitting diodes (OLEDs) using f-TX-TPA as an emitter exhibited a high external quantum e?ciency of 15.9%. These results indicated that angular-fused dithianaphthylquinone derivatives could have great potential in the application of high-e?ciency OLEDs.
关键词： thermally activated delayed ?uorescence,organic light-emitting diode,angular-fused dithianaphthylquinone,high-e?ciency
更新于2025-09-19 17:13:59
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Ecological biosubstrates obtained from onion pulp ( <i>Allium cepa L.</i> ) for flexible organic light-emitting diodes
摘要： A new biopolymer obtained from onion pulp - Allium cepa L. - was employed to produce sustainable substrates for flexible organic light-emitting diodes (FOLEDs). Indium tin oxide (ITO) and SiO2 thin films were deposited by rf-magnetron sputtering onto these bio-substrates to obtain flexible, transparent and conductive anodes on top of which FOLEDs were produced. This new biomaterial exhibits optical transparency of 63 % at 550 nm. ITO films were optimized by varying rf-power during deposition onto the biopolymers and their electrical properties are comparable to the ones of ITO grown on top of rigid substrates: carrier concentration of -3.63 × 1021 cm?3 and carrier mobility of 7.72 cm2V-1s-1 for the optimized film. Consequently, the sheet-resistance and resistivity of this ITO film were 8.92 Ω□-1 and 2.23 × 10-4 Ωcm, respectively, hence allowing the production of FOLEDs. The Allium cepa L. based FOLED was fabricated using CuPc, β-NPB and Alq3 as organic layers, and it exhibited a maximum luminance of about 2062 cdm-2 at 16.6 V. The current efficiency reached a maximum value of 2.1 cdA-1 at 85.3 mAcm-2. The obtained results suggest the possibility to use these substrates for innovative biocompatible applications in optoelectronics, such as photodynamic therapy.
关键词： biosubstrate,Allium cepa L.,biopolymer,FOLED,flexible organic light-emitting diode
更新于2025-09-19 17:13:59
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Structural isomers of 9-(pyridin-2-yl)-9H-carbazole in combination with 9a?2H-9,3':6a?2,9a?3-tercarbazole and their application to high efficiency solution processed green TADF OLEDs
摘要： Two host materials, CzPy2TCz and CzPy3TCz, were designed as structural isomers and synthesized to achieve high efficiency thermally activated delayed fluorescence-organic light emitting diodes (TADF-OLEDs). The design strategy involved introducing a pyridine group into the core structure as an electron-withdrawing unit and varying the substitution position of tercarbazole (TCz). To realize green TADF-OLED, the two host materials synthesized in this study have excellent thermal stability and high excited triplet energy (T1 ? 2.95–2.98 eV). The maximum external quantum efficiency and current efficiency values for CzPy2TCz were 23.81% and 80.2 cd/A, respectively and the respective values for CzPy3TCz were 20.27% and 70.1 cd/A, respectively. Structural isomers with carbazole (Cz) and TCz units at the 2,6-position of the pyridine core effectuate better device performance. Consequently, we found that the host materials introduced in this study play an important role in implementing high performing solution-processed green TADF-OLED.
关键词： Thermally activated delayed fluorescence,Organic light-emitting diode,Tercarbazole,Pyridine,Host material,Solution process
更新于2025-09-19 17:13:59