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Single Component Self-Assembled Thermally Activated Delayed Fluorescence Nanoprobe
摘要： A novel versatile thermally activated delayed fluorescence (TADF) nanoprobe, AI-Cz-NP, was designed and fabricated through self-assembly of the single-component amphiphilic monomer for potential applications in confocal imaging and time-resolved fluorescence imaging.
关键词： nanoprobe,self-assembly,thermally activated delayed fluorescence,confocal imaging,time-resolved fluorescence imaging
更新于2025-09-16 10:30:52
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Mixed-Host Systems with a Simple Device Structure for Efficient Solution-Processed Organic Light-Emitting Diodes of a Red-Orange TADF Emitter
摘要： Charge balance, concentration quenching, and exciton con?nement are the most important factors for realizing the use of thermally activated delayed ?uorescence (TADF) emitters for organic light-emitting diodes. Red-orange organic light-emitting diodes of a TADF emitter 2-[4 (diphenylamino)phenyl]-10,10-dioxide-9H-thioxanthen-9-one (TXO-TPA) have been reported by doping in a mixed p-type host system of poly(N-vinylcarbazole) (PVK) and 1,3-bis(N-carbazolyl)benzene (mCP) via solution-processed. We have demonstrated the peak external quantum e?ciency of 9.75%, maximum current e?ciency of 19.36 cd/A, and power e?ciency of 12.17 lm/W along with a CIE coordinate of (0.45, 0.51). The devices were compared with di?erent doping concentrations of TXO-TPA, and a comparative investigation on the e?ect of the thickness electron transport layer was studied. The results clearly indicated that this solution-processed TXO-TPA device structure is a promising strategy to develop highly e?cient but simple OLED structures.
关键词： external quantum e?ciency,thermally activated delayed ?uorescence,red-orange,solution-processed,organic light-emitting diodes
更新于2025-09-16 10:30:52
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Transition metal ion Co-Doped MgO–MgF2-GeO2:Mn4+ red phosphors for white LEDs with wider color reproduction gamut
摘要： Mn4+-activated non-rare-earth based red phosphors are excellent down conversion materials for phosphor-converted light-emitting diode (pc-LEDs) based solid-state lighting applications. However, the low quantum efficiency of Mn4+ activated red phosphors under InGaN based blue LED excitation hinders their use in phosphor-converted LEDs. To enhance the absorption at an excitation wavelength of around 420 nm in Mn4+-doped MgO-MgF2-GeO2 (MGF: Mn4+), which is a conventional red-emitting lamp phosphor, we doped MGF: Mn4+ phosphors with transition metal oxides (Sc2O3, Lu2O3, Y2O3, and La2O3) replacing MgO. When excited using 420 nm light, the absorption ratio of the synthesized phosphors with Sc2O3 (Sc-MGF:Mn4+) was 58% with an internal quantum efficiency (IQE) of 55% as compared to the 35% IQE of the pristine MGF-Mn4+ phosphor. White LEDs were fabricated using Sc-MGF-Mn4+ (red), and β-SiAlON:Eu2+ (green) on InGaN chips (λem = 450 nm) and their performance was compared to the optical performance of LEDs fabricated using K2SiF6:Mn4+ as the red phosphor. According to the National Television System Committee (NTSC) standard, the color reproduction coverage with an Sc-MGF:Mn4+ phosphor-loaded white LED was 121% by the International Commission on Illumination (CIE) 1976, and 80% by the BT.2020 standard. The coverages are 9% and 6% higher than the coverages of LEDs fabricated using K2SiF6:Mn4+ as the red phosphor according to the NTSC and BT.2020 standards, respectively. Our simple approach to enhance the IQE of Mn4+ activated phosphors by co-doping transition metal oxides can be extended to other Mn4+ activated phosphor systems for applications that require enhanced absorption, higher luminescent emission intensity, and a wider gamut of color reproduction.
关键词： MgO-MgF2-GeO2,Mn4+ activated red phosphors,Solid-state lighting,White LEDs,BT.2020
更新于2025-09-12 10:27:22
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All-solution processed inverted QLEDs with double hole transport layers and thermal activated delay fluorescent dopant as energy transfer medium
摘要： Highly efficient, all-solution processed inverted quantum dot light-emitting diodes (QLEDs) with high performance are demonstrated by employing poly(9-vinlycarbazole) (PVK) as additional hole transport layer (HTL) and doping it with a blue thermal activated delay fluorescent (TADF) material, 4,5-bis(carbazol-9-yl)-1,2-dicyanobenzene (2CzPN). This PVK: 2CzPN composite layer not only optimizes hole injection, but also utilizes the leaked electrons to enhance device luminance by energy transfer process from 2CzPN to quantum dots (QDs). These benefits enable a 20-fold increment for the device current efficiency (from 0.523 cd/A to 11 cd/A) and a 9.9-fold improvement for the maximum luminance (from 3220 cd/m2 to 35352 cd/m2), compared with those of the standard QLED with poly[(9, 9-dioctylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-butylphenyl) (TFB) single HTL. In comparison with the QLED with TFB/pristine PVK double HTLs, the device performance of the optimal QLED with PVK: 2CzPN additional HTL are still 40.8% and 61.7% higher in luminance and current efficiency, respectively.
关键词： Thermally activated delayed fluorescence,Quantum dot light-emitting diode,All-solution process,Energy transfer,Double hole transport layers,Inverted structure
更新于2025-09-12 10:27:22
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Facile structure-modification of xanthenone based OLED emitters exhibiting both aggregation induced emission enhancement and thermally activated delayed fluorescence
摘要： Four new donor-acceptor compounds were designed, synthesized and investigated by theoretical and experimental approaches aiming to estimate effect of the structure of a donor on the properties of potential OLED emitters. Because of the different electron-donating abilities of the nitrogen-containing heterocycles, derivatives of xanthenone containing di-tert-butyl-carbazolyl, di-tert-butyl-acridanyl, di-tert-butyl-phenothiazinyl and penoxazinyl moieties exhibited different photophysical behavior. Because of big dihedral angles between the donors and acceptor as well as because of possibility of rotation around N-C bond, the designed compounds were characterized by thermally activated delayed fluorescence and aggregation induced emission enhancement effect. Twice higher photoluminesce quantum yields reaching 38% in doped films were obtained for compounds containing di-tert-butyl-carbazolyl and di-tert-butyl-acridanyl moieties as compared to those observed for compounds with the donors containing S and O heteroatoms. Strong effect of the donor substituents on charge injection (ionization potentials were in the range of 5.67-5.96 eV) and charge-transporting properties (hole and electron mobilities were in a wide range from 6.3×10-8 to 6.3×10-4 cm2V-1s-1 at electric field of 2.5×105 V·cm-1) was detected. The differently substituted compounds were utilized as emitters in OLEDs. Higher maximum values of external quantum efficiency (up to 3.5%) were observed for OLEDs based on emitters with nitrogen containing donors relative to estimated for OLEDs based on emitters containing di-tert-butyl-phenothiazinyl and penoxazinyl moieties.
关键词： aggregation induced emission enhancement,xanthenone,Organic light-emitting diode,thermally activated delayed fluorescence
更新于2025-09-12 10:27:22
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Molecular Engineering of Thermally Activated Delayed Fluorescence Emitters with Aggregation-Induced Emission via Introducing Intramolecular Hydrogen-Bonding Interactions for Efficient Solution-Processed Nondoped OLEDs
摘要： Purely organic luminescent materials concurrently exhibiting thermally activated delayed fluorescence (TADF) and aggregation-induced emission (AIE) features are in great demand due to their high efficiency in aggregation-state toward efficient non-doped OLEDs. Herein, a class of thermally activated delayed fluorescence (TADF) emitters adopting phenyl(pyridyl)methanone as electron-accepting segment and di(tert-butyl)carbazole and 9,9-dimethyl-9,10-dihydroacridine (or phenoxazine) as electron-donating groups are designed and synthesized. The existence of intramolecular hydrogen bonding is conducive to minish the energy difference between singlet and triplet (ΔEst), suppress non-radiative decay and increase the luminescence efficiency. By using 3CPyM-DMAC as emitter, the non-doped device via solution process realize high current efficiency (CE) and external quantum efficiency (EQE) of 35.4 cd A-1 and 11.4 %, respectively, which is superior to that of CBM-DMAC with CE and EQE of 14.3 cd A-1 and 6.7 %. This work demonstrates a promising tactics to the establishment of TADF emitters with AIE features via introducing intramolecular hydrogen-bonding.
关键词： organic light-emitting diodes (OLEDs),nondoped,thermally activated delayed fluorescence (TADF),solution processed,aggregation-induced emission (AIE)
更新于2025-09-12 10:27:22
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Through-space charge transfer in luminophore based on phenyl-linked carbazole- and phthalimide moieties utilized in cyan-emitting OLEDs
摘要： Two new carbazole-containing aromatic imides were synthesized by three-step synthetic pathway with the moderate yields up to 76%. The compounds were investigated theoretically. TD-DFT computational studies revealed low singlet-triplet energy di?erences. The compounds were found to have relatively high thermal stability with 5% mass loss temperatures in the range of 280–310 °C. Phthalimide-based compound exhibited aggregation-induced emission enhancement and thermally activated delayed ?uorescence with photo-luminescence quantum e?ciency of 20% in the solid state. Structure-properties relationship of this compound was investigated and it was found that charge-transfer through space mechanism is responsible for the emission. Series of green-emitting doped and non-doped electroluminescent devices were fabricated based on the carbazole-phthalimide derivative were fabricated to reveal best-performing mCP-doped device demonstrating maximum external quantum e?ciency of 2.4% with current e?ciency of 6.6 cd/A and power e?ciency of 4.0 lm/W with maximum brightness of 8300 cd/m2.
关键词： Cyan-emitting OLED,Aromatic imide,Through-space charge transfer,Aggregation-induced emission enhancement,Thermally activated delayed ?uorescence
更新于2025-09-12 10:27:22
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Cyclohexane-cored dendritic host materials with high triplet energy for efficient solution-processed blue thermally activated delayed fluorescence OLEDs
摘要： Two dendritic host materials (CH-2D1 and CH-2D2) are developed by using non-conjugated cyclohexane core and two first/second generation carbazole dendrons, which show excellent solubility in organic solvents, high thermal stability and high triplet energy (ET) of 2.78–2.84 eV, making them suitable for fabrication of solution-processed blue thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs). Compared to CH-2D1 with the first-generation carbazole dendron which shows low-lying highest occupied molecular orbital (HOMO) energy level of (cid:0) 5.48 eV, CH-2D2 with the second-generation carbazole dendrons exhibits higher HOMO level of (cid:0) 5.37 eV, which is more favourable for hole injection from the anode to the emissive layers. Consequently, solution-processed blue TADF OLEDs utilizing CH-2D2 as host show promising device performance with a low turn-on voltage of 3.4 V, maximum external quantum efficiency of 17.8%, (cid:0) 1, which can compare with the most efficient solution-processed blue TADF OLEDs based on small-molecule and polymer hosts. These results indicate that dendritic host materials with well-defined chemical structure and good solubility are an attractive approach–beyond the soluble small-molecule hosts and polymer hosts–for the development of efficient solution-processed TADF OLEDs.
关键词： Thermally activated delayed fluorescence,Dendritic host materials,Organic light-emitting diodes,High triplet energy
更新于2025-09-12 10:27:22
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Phthalonitrile-based bipolar host for efficient green to red phosphorescent and TADF OLEDs
摘要： A bipolar host material named 4-(9H-carbazol-9-yl)phthalonitrile (CzPN) was developed by combining carbazole and phthalonitrile as donor and acceptor units, respectively. The introduction of the phthalonitrile unit realized a relatively small energy gap of 3.00 eV as well as a deep lowest unoccupied molecular orbital level of ?2.72 eV. The characterization of carrier-only devices demonstrated the bipolar charge transporting property of CzPN. With a triplet energy of 2.70 eV, CzPN was investigated as host in green, yellow, and red phosphorescent organic light-emitting diodes (PhOLEDs) and green thermally activated delayed fluorescence (TADF) devices. A low turn-on voltage of 2.8 V was achieved by all the four diodes. Both PhOLEDs and TADF devices exhibited high external quantum efficiency values over 20% with relatively small efficiency roll-offs. These findings demonstrate that CzPN is an excellent host material for both phosphorescent and TADF emitters, and phthalonitrile is a promising unit to develop universal host materials.
关键词： Phthalonitrile,Bipolar host,Phosphorescent organic light-emitting diode,Thermally activated delayed fluorescence
更新于2025-09-12 10:27:22
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J-aggregation Enhances the Electroluminescence Performance of Sky-blue TADF Emitter in Non-doped OLEDs
摘要： A pivotal thermally activated delayed fluorescence (TADF) emitter DspiroAc-TRZ was developed, and it exhibits greatly enhanced electroluminescence performance in non-doped organic light-emitting diodes (OLEDs) owing to the concurrent manipulation of aggregation behavior and monomolecular structure. The delicate non-planar packing pattern in DspiroAc-TRZ crystal can not only lead to highly efficient solid-state luminescence, but also form loose intermolecular packing pattern, greatly decreasing the HOMOs or LUMOs overlaps in dimers and shortening triplet exciton diffusion length. In addition, the rigid donor and acceptor moieties in DspiroAc-TRZ can rigidify the molecular backbone, resulting in tiny geometry vibrational relaxation in excited state. Impressively, high photoluminescent quantum yields (PLQYs) of 78.5% and 83.7% were achieved for DspiroAc-TRZ single-crystal and non-doped film. A high external quantum efficiency (EQE) of 25.7% was achieved in non-doped sky-blue TADF-OLED, which is higher than any reported EQE values of non-doped sky-blue TADF-OLEDs so far.
关键词： molecular orientation,non-doped,thermally activated delayed fluorescence,organic electronics,organic light-emitting diodes
更新于2025-09-12 10:27:22