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A bipolar deep blue-emitting fluorescent material based on imidazole and triphenylamine for efficient non-doped OLEDs
摘要： A bipolar deep blue-emitting fluorescent material, 1-(4-tert-butyl phenyl)-2-[4-(N,N- diphenyl)phenyl]-4,5-diphenyl-1H-imidazole (TPA-PIM) has been designed and synthesized for efficient blue organic light-emitting diodes (OLEDs). The photophysical, thermal and electrochemical properties of TPA-PIM are investigated. TPA-PIM possesses high thermal stabilities with decomposition temperature of 396 °C and shows a strong deep-blue emission at 407 nm in N, N-dimethylformamide (DMF) solution. Single-carrier devices are fabricated to show that TPA-PIM has good bipolar characteristics. The non-doped fluorescent OLEDs using TPA-PIM as emitter exhibited stable and efficient deep-blue emissions with the CIE coordinates of (0.16, 0.09), the maximum luminance of 1392 cd m?2 and the maximum current efficiency of 2.60 cd A?1.
关键词： Triphenylamine,Blue light-emitting materials,Bipolar materials,Imidazole,Non-doped OLEDs
更新于2025-11-19 16:56:42
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High Efficiency Non‐Doped White Organic Light Emitting Diodes Based on a Bilayer Interface‐Exciplex Structure
摘要： High efficiency non-doped blue and white organic light emitting diodes (OLEDs) are realized by using a bilayer interface-exciplex (i-Exc) structure. Since the neutral exciplex are formed at the interface, the interface charge accumulation is reduced, thereby suppressing exciton quenching in the device. With the i-Exc structure, a maximum external quantum efficiency (EQE) of 23.1% is achieved in the non-doped blue phosphorescent OLED. Moreover, the white emission can be obtained by inserting an ultrathin orange-red phosphorescent emitter into the blue devices. The charge trapping in the orange-red emitter can be suppressed by adjusting the position of the ultrathin orange-red emitting layer in the device, contributing to superior spectral stability. The WOLED achieves an EQE of 20.0% and exhibits a stable warm white emission. The Commission Internationale de l’Eclairage (CIE) coordinates of WOLED are (0.41, 0.40) at 5 V and slightly change to (0.40, 0.41) at 9 V.
关键词： interface-exciplex,PHOLED,WOLED,bilayer structure,ultrathin non-doped emitting layers
更新于2025-11-14 15:26:12
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Non-doped phosphorescent organic light-emitting devices with an exciplex forming planar structure for efficiency enhancement
摘要： Organic light-emitting devices (OLEDs) consisting of a non-doped phosphorescent dye that inserted in an exciplex forming planar structure have been fabricated, and the thickness of ultrathin phosphor layer is optimized to achieve high efficiency. The results showed that OLEDs based on the exciplex interface and a 0.5 nm thick phosphorescent dye have a power efficiency, a current efficiency, and an external quantum efficiency of 37.4 lm/W, 40.5 cd/A, and 14.3%, respectively, which are almost two-folds higher than those with non-exciplex interface devices. Meanwhile, the efficiency roll-off is significantly suppressed. These improved device performances are attributed to the elimination of triplet energy leakage from exciplexes to constituting molecules, efficient energy up conversion of triplet exciplexes and complete host-guest F?rster energy transfer. These results will provide an easily-fabricated and time-saving approach for high-performance OLEDs.
关键词： non-doped,planar structure,Organic light-emitting device (OLED),exciplex,phosphorescent dye
更新于2025-09-23 15:22:29
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Efficient non-doped blue fluorescent OLEDs based on bipolar phenanthroimidazole-triphenylamine derivatives
摘要： Blue organic emissive materials are still the most important bottlenecks for the development of organic light-emitting diodes (OLEDs). To enrich the material library, herin, three bipolar phenanthroimidazole derivatives, namely MePPIM-TPA, ClPPIM- TPA and BuPPIM-TPA, are synthesized using triphenylamine as electron-donor and phenanthroimidazole as the electron-acceptor. The photophysical, thermal and electrochemical properties of three compounds are investigated with high decomposition temperature up to 350 °C, and strong blue emission. Single-carrier devices are fabricated to show that three compounds have good bipolar carrier transport characteristic. The non-doped fluorescent OLEDs devices using three compounds as emitting layers are fabricated among which the devices based on MePPIM-TPA achieved the maximum luminance of 1743 cd/m2, the maximum external quantum efficiency (EQE) of 2.99% which is relatively comparable to commonly used blue emitters.
关键词： Non-doped OLEDs,Bipolar characteristic,Triphenylamine,Fluorescent materials,Phenanthroimidazole
更新于2025-09-23 15:19:57
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Tert-butyl Substituted Hetero-donor TADF compounds for Efficient Solution-Processed Non-doped Blue OLEDs
摘要： For the development of solution-processed organic light-emitting diodes (OLEDs), it is highly desirable and challenging for releazing solution-processable non-doped thermally activated delayed fluorescence (TADF) emitters due to their high efficiency and excellent compatibility to the wet methods. Herein, two pairs of blue TADF isomers are designed and synthesized with a hetero-donor configuration for the realization of high photoluminescent quantum yield. The incorporation of two tert-butyl groups in the molecules can effectively increase the molecular solubility and reduce the aggregation-caused self-quenching of excitons in neat films by inhibiting the intramolecular vibrational relaxation and the intermolecular π-π stacking. Solution-processed non-doped OLEDs are achieved with these blue TADF emitters, exhibiting the record-high external quantum efficiencies (EQE) of 25.8%. Furthermore, all-TADF white OLED with an EQE of 27.3% is also achieved by employing a single emitting layer with the blue TADF emitter as a host for an orange-red TADF dopant.
关键词： non-doped OLED,blue fluoresecent materials,Organic light-emitting diodes,solution process,thermally activated delayed fluorescence
更新于2025-09-23 15:19:57
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Highly efficient non-doped blue fluorescent OLEDs with low efficiency roll-off based on hybridized local and charge transfer excited state emitters
摘要： Designing a donor-acceptor (D-A) molecule with a hybridized local and charge transfer (HLCT) excited state is a very effective strategy for producing an organic light-emitting diode (OLED) with a high exciton utilization efficiency and external quantum efficiency. Herein, a novel twisting D-π-A fluorescent molecule (triphenylamine-anthracene-phenanthroimidazole; TPAAnPI) is designed and synthesized. The excited state properties of the TPAAnPI investigated through photophysical experiments and density functional theory (DFT) analysis reveal that its fluorescence is due to the HLCT excited state. The optimized non-doped blue OLED using TPAAnPI as light-emitting layer exhibits a novel blue emission with an electroluminescence (EL) peak at 470 nm, corresponding to the Commission International de L’Eclairage (CIE) coordinates of (0.15, 0.22). A fabricated device termed Device II exhibits a maximum current efficiency of 18.09 cd A ?1, power efficiency of 12.35 lm W?1, luminescence of ≈29900 cd cm?2, and external quantum efficiency (EQE) of 11.47%, corresponding to a high exciton utilization efficiency of 91%. Its EQE remains as high as 9.70% at a luminescence of 1000 cd m?2 with low efficiency roll-off of 15%. These results are among the best for HLCT blue-emitting materials involved in non-doped blue fluorescent OLEDs. The performance of Device II highlights a great industrial application potential for the TPAAnPI molecule.
关键词： HLCT,efficiency roll-off,blue emission,non-doped,OLED
更新于2025-09-23 15:19:57
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Calix[4]resorcinarene-based Hyper-Structured Molecular Thermally Activated Delayed Fluorescence Yellow-Green Emitters for Non-doped OLEDs
摘要： A novel hyper-structured molecular (HSM) thermally activated delayed fluorescent (TADF) emitters, in which the TADF units and host units are bound together into one inactive core through the flexible linkage, was designed. Phenoxazine-triphenyltriazine (PXZ-Trz), 1,3-bis(9H-carbazol-9-yl)benzene (mCP) and calix[4]resorcinarene (CRA) were chosed as TADF unit, host unit and core, respectively, a series of CRA-based HSM emitter, CRA-PXZ-Trz(X)-mCP(100-X). (x=0, 12.5, 25, 50, 75, 87.5 or 100) were succesfully synthesized by a two-step click reaction. Using non-doped CRA-PXZ-Trz(87.5)-mCP(12.5) as the light-emitting layer, the solotion-precessable OLEDs emitted yellow-green light, and dispiayed a external quantum efficiency of 16.7% at 100 cd/m2.
关键词： Thermally activated delayed fluorescence,Solution-processable,Non-doped OLEDs,Calix[4]resorcinarene,Hyper-structured molecular
更新于2025-09-19 17:13:59
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Facile generation of thermally activated delayed fluorescence and fabrication of highly efficient non‐doped OLEDs based on triazine derivatives
摘要： A series of donor-acceptor-donor triazine-based molecules with thermally activated delayed fluorescence (TADF) properties were synthesized to obtain highly efficient blue-emitting OLEDs with non-doped emitting layer (EML). The targeted molecules use a triazine core as the electron acceptor, and a benzene ring as the conjugated linker with different electron donors to alternate the energy level of HOMO to further tune the emission color. The introduction of long alkyl chains on the triazine core inhibits the unwanted intermolecular D-D/A-A type π-π interactions, resulting in the intermolecular D-A charge transfer. The weak aggregation-caused quenching (ACQ) effect caused by the suppressed intermolecular D-D/A-A type π-π interaction further enhances the emission. The crowded molecular structure allows the electron donor and acceptor to be nearly orthogonal, thereby reducing the energy gap between triplet and singlet excited states (ΔEST). As a result, blue-emitting devices with TH-2DMAC and TH-2DPAC non-doped EML showed satisfactory efficiencies of 12.8% and 15.8%, respectively, which is one of the highest EQEs reported in the blue TADF emitters (λpeak < 475 nm), demonstrating that our tailored molecular designs are promising strategies to endow OLEDs with excellent EL performances.
关键词： triazine derivatives,non-doped emitting layer,OLEDs,blue-emitting,thermally activated delayed fluorescence,TADF
更新于2025-09-19 17:13:59
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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
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Management of Exciton for Highly-Efficient Hybrid White Organic Light-Emitting Diodes with a Non-Doped Blue Emissive Layer
摘要： Hybrid white organic light-emitting diodes (WOLEDs) have drawn great attention both for display and solid-state lighting purposes because of the combined advantages of desirable stability of ?uorescent dyes and high e?ciency of phosphorescent materials. However, in most WOLEDs, obtaining high e?ciency often requires complex device structures. Herein, we achieved high-e?ciency hybrid WOLEDs using a simple but e?cacious structure, which included a non-doped blue emissive layer (EML) to separate the exciton recombination zone from the light emission region. After optimization of the device structure, the WOLEDs showed a maximum power e?ciency (PE), current e?ciency (CE), and external quantum e?ciency (EQE) of 82.3 lm/W, 70.0 cd/A, and 22.2%, respectively. Our results presented here provided a new option for promoting simple-structure hybrid WOLEDs with superior performance.
关键词： hybrid,exciton management,non-doped blue emissive layer,white organic light-emitting diodes
更新于2025-09-12 10:27:22