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Wavelength-Turnable Organic Micro-ring Laser Arrays from Thermally Activated Delayed Fluorescent Emitters
摘要： Organic solid-state lasers (OSSLs) have been paid great attention due to their ease-of-fabrication, low cost and tailor-made molecular tunability. Optical gain materials of OSSLs are currently focused on fluorescent materials, which can bring only 25% exciton utilization for future current-injection OSSLs due to spin statics under electrical excitation. While thermally active delayed fluorescent (TADF) materials can obtain a theoretical 100% internal quantum efficiency by harvesting triplet excitons. However, OSSLs based on TADF materials remain largely unexplored yet. Here, we report the first TADF-based OSSL from whispering-gallery mode micro-ring resonator arrays fabricated by a confined solution-growth method. The newly designed TADF emitter of carbozyl borondifluoride curcuminoid derivative, namely, CAZ-A, when doped into a host matrix of 4,4'-bis(N-carbazolyl)-1,10-biphenyl (CBP), reaches the highest gain-coefficient of 640 cm-1 at 4 wt%. These MRs with well-controlled sizes and uniform geometries constitute a high quality (cavity quality factor Q ~ 1300) built-in WGM resonators and exhibit outstanding multi-mode laser behaviors. By varying TADF molecule doping concentration, the laser wavelength can be continuously tuned in the red spectral range from 650 nm to 725 nm. As CBP is usually used as the host material for active layers in OLEDs, we believe that CAZ-A/CBP doping material is good candidate for future electrically driven OSSLs.
关键词： wavelength tunability,micro-ring laser arrays,whispering-gallery mode,host-guest doping,thermally activated delayed fluorescence (TADF)
更新于2025-09-12 10:27:22
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Modulation of F?rster and Dexter Interactions in Single‐Emissive‐Layer All‐Fluorescent WOLEDs for Improved Efficiency and Extended Lifetime
摘要： White organic light-emitting diodes (WOLEDs) with thermally activated delayed fluorophor sensitized fluorescence (TSF) have aroused wide attention, considering their potential for full exciton utilization without noble-metal containing phosphors. However, performances of TSF-WOLEDs with a single-emissive-layer (SEL) still suffer from low exciton utilization and insufficient blue emission for proper white balance. Here, by modulating F?rster and Dexter interactions in SEL-TSF-WOLEDs, high efficiencies, balanced white spectra, and extended lifetimes are realized simultaneously. Given the different dependencies of F?rster and Dexter interactions on intermolecular distances, sterically shielded blue thermally activated delayed fluorescence (TADF) emitters and orange conventional fluorescent dopants (CFDs) with electronically inert peripheral units are adopted to enlarge distances of electronically active chromophores, not only blocking the Dexter interaction to prevent exciton loss but also finely suppressing the F?rster one to guarantee balanced white emission with sufficient blue components. It thus provides the possibility to maximize device performances in a large range of CFD concentrations. A record high maximum external quantum efficiency/power efficiency of 19.6%/52.2 lm W?1, Commission Internationale de L’Eclairage coordinate of (0.33, 0.45), and prolonged half-lifetime of over 2300 h at an initial luminance of 1000 cd m?2 are realized simultaneously for SEL-TSF-WOLEDs, paving the way toward practical applications.
关键词： sensitizing process,thermally activated delayed fluorescence,exciton interactions,white organic light-emitting diodes,sterically inert substituents
更新于2025-09-12 10:27:22
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Cruciform Molecules Bearing Bis(phenylsulfonyl)benzene Moieties for High‐Efficiency Solution Processable OLEDs: When Thermally Activated Delayed Fluorescence Meets Mechanochromic Luminescence
摘要： Four crucifix-shaped molecules, named TPA-BPSB, DMAc-BPSB, MTPA-BPSB and MDMAc-BPSB, bearing the same acceptor fragment of bis(phenylsulfonyl)benzene (BPSB) and different donor segments (TPA and MTPA are the diphenylamine derivatives while DMAc and MDMAc are the 9,9-dimethylacridine derivatives) are synthesized and characterized by NMR, mass spectra, and single crystal X-ray crystallography. The molecular structure–property relationship of these crucifix-shaped molecules is systematically explored. All compounds display thermally activated delayed fluorescence (TADF) in the region of 500–550 nm. In addition, charming mechanochromic luminescence properties are observed for all these TADF molecules under external stimuli, such as grinding and exposure to CH2Cl2 vapor. Four TADF molecules are used as the emitters in organic light-emitting diodes (OLEDs) fabricated via solution process. MTPA-BPSB-based device presents a best performance with a highest external quantum efficiency of ≈21%, which is among the highest efficiencies for reported BPSB-based solution-processable OLEDs so far. This research has an important significance in designing high-efficiency multifunctional TADF molecules.
关键词： bis(phenylsulfonyl)benzene,thermally activated delayed fluorescence,mechanochromic luminescence,crucifix-shaped molecules,solution processable OLEDs
更新于2025-09-12 10:27:22
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High efficiency, high color rendering index white organic light-emitting diodes based on thermally activated delayed fluorescence materials
摘要： High ef?ciency white organic light-emitting diodes (WOLEDs) with simple device architecture are desirable for next-generation light sources. However, it is still challenging in the construction of high-performance WOLEDs with a simple device structure. Based on a thermally activated delayed ?uorescence (TADF) blue emitter 2SPAc-MPM and a TADF yellow emitter TXO-TPA, high performance two-color WOLEDs with simple device architecture are demonstrated. Bene?ting from ef?cient energy transfer and wide coverage over the visible spectrum, optimized WOLED devices that have a single emitting layer (s-EML) provide a maximum color rendering index (CRI) and maximum external quantum ef?ciency (EQE) of 78.1 and 21.8%, respectively. More importantly, with multiple emitting layers (m-EMLs), a maximum EQE of 14.5% and a high CRI of 90.7 can be achieved. These results are among the best for the two-color WOLEDs with two TADF emitters.
关键词： white organic light-emitting diodes,high efficiency,thermally activated delayed fluorescence,high color rendering index
更新于2025-09-12 10:27:22
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Benzoylpyridine-based TADF emitters with AIE feature for efficient non-doped OLEDs by both evaporation and solution process
摘要： Fluorescent materials taking both advantages of evaporation and solution processes are urgently explored for the development of efficient and simplified organic light-emitting diodes (OLEDs). Furthermore, it is another huge challenge for such materials to achieve excellent electroluminescence performances in non-doped OLEDs. Herein, two new emitters, named as PyB-DPAC and PyB-DMAC with 4-benzoylpyridine moiety as the electron acceptor and 9,9-diphenyl-9,10-dihydroacridine or 9,9-dimethyl-9,10-dihydroacridineas the electron donor were synthesized and explored. Both emitters exhibit distinct TADF character, typical AIE feature and relatively high photoluminescence quantum yields. Accordingly, we demonstrated efficient non-doped vacuum-deposited OLED based on the PyB-DPAC with a maximum external quantum efficiency (EQE) up to 9.7%, and meanwhile an extremely low efficiency roll-off of 1.7% at a high brightness of 1000 cd m-2. In addition, an impressive EQE of 11.1% can be realized from the solution-processed non-doped devices with the using of PyB-DPAC emitter. These affirmative results manifest that TADF emitters incorporate with the benzoylpyridine acceptor enabling a promising molecular design strategy in adapt to the non-doped evaporation- and solution-processed highly efficient OLEDs.
关键词： benzoylpyridine,Organic light-emitting diode,thermally activated delayed fluorescence,aggregation-induced emission
更新于2025-09-12 10:27:22
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Improving the Stability of Green Thermally Activated Delayed Fluorescence OLEDs by Reducing the Excited-State Dipole Moment
摘要： Highly efficient organic light-emitting diodes (OLEDs) employing metal-free thermally activated delayed fluorescence (TADF) emitters have attracted much attention in recent years. Efficient TADF mainly occurs in charge-transfer (CT) molecules. Here, we demonstrate that a small dipole moment for TADF emitters in the S1 state is key for device stability by comparing two green TADF emitters with the same moieties but different types of linker. The compound 1AC-TRZ with a 9,9-dimethyl-9,10-dihydroacridine donor and a triphenyltriazine acceptor attached at the 1- and N-positions of carbazole has a smaller excited-state dipole moment (11 D) than the 3- and N-substituted analog 3AC-TRZ (30 D). Although the emission spectra and efficiencies of their devices are similar, the operational lifetime of the 1AC-TRZ-based device is much longer than that of the 3AC-TRZ-based device. Time-resolved emission spectra indicate that the S1 energy of 3AC-TRZ in doped films is higher than that of 1AC-TRZ at the start of nanosecond solvation relaxation. A photodegradation experiment suggests that the short-term existence (<1 ns) of high energy (>2.9 eV) excitons can hasten the upconversion-induced degradation in films. Our study reveals a relationship between solid-state solvation and OLED stability and provides a new guideline for designing stable green and blue TADF emitters.
关键词： Dipole Moment,Green Emitters,Stability,Thermally Activated Delayed Fluorescence,OLED
更新于2025-09-12 10:27:22
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A Study of the Effect of Anisotropic Gold Nanoparticles on Plasmonic Coupling with a Photosensitizer for Antimicrobial Film.
摘要： Development of antimicrobial surfaces for sterilization is much needed to avoid the spreading of drug resistant bacteria. Light can activate antimicrobial surfaces by an interaction between nanoparticles and a photosensitizer dye, to produce a steady and efficient killing of bacteria. The film studied in this work contains gold nanorods (AuNRs) of 32 nm length and 16 nm diameter and gold nanostars (AuNSs) of 50 nm of diameter, in combination with crystal violet dye (CV). The surface plasmon resonance (SPR) of the nanoparticles used in the film was mathematically simulated and characterized to understand difference SPR between the particles. Their effects on plasmonic coupling with the dye, thus the production of reactive oxygen species (ROS) and consequently the activity of the film against bacteria were studied. The films showed great antimicrobial activity against gram negative bacteria (E. coli) in 4 h of light exposure, when modified with AuNSs, it could kill E. coli in 5 orders of magnitudes (5-log) and the one modified with AuNRs could kill with 4 order of magnitudes (4-log). While maintaining partial activity against gram positive bacteria (S. aureus), i.e. being able to kill in 2.5 orders of magnitudes by the film containing AuNSs and 3 orders of magnitudes by those containing AuNRs. The differential response of gram (-) and gram (+) bacteria to the ROS generated by the films, would allow more targeted approach for specific bacterial species, for example, surfaces of bedpans or common contact surfaces (handles, handrails etc.) that are contaminated principally by gram (-) or gram (+) bacteria, respectively.
关键词： anisotropy,light-activated,non-contact sterilization,antimicrobial surface,simulations,Plasmonic coupling
更新于2025-09-12 10:27:22
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45.4: High Performance of Deep Blue OLEDs with Thermally Activated Sensitized Fluorescence Technology
摘要： The low efficiency of blue devices has been a bottleneck problem for OLED panel manufacturers for a long time. In this paper, we present the development of TASF materials technology for deep blue OLEDs with high Blue Index (current efficiency/CIE-y) around 300 at CIE-y=0.078 obtained at 1000 cd/m2.
关键词： TADF,TASF,high-efficiency,Thermally Activated Delayed Fluorescence,Thermally Activated Sensitized Fluorescence,deep blue,OLED
更新于2025-09-11 14:15:04
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Recent progress on exciplex-emitting OLEDs
摘要： The thermally-activated-delayed-fluorescence (TADF) characteristics makes exciplexes being the hot subject in the organic light-emitting diode (OLED) research field. The theoretical limit for the efficiency of the conventional fluorescent OLEDs have been leaped by exploiting the triplet harvesting ability of exciplexes. Exciplexes are easily formed by blending electron donor molecules and electron acceptor molecules, which are generally hole transporting materials and electron transporting materials, respectively, resulting in easy access for employing exciplexes to OLEDs. We introduce the photo-physical characteristics of exciplexes derived from the charge-transfer characteristics and their application to OLEDs as emitters. Single exciplex-emitting OLEDs as well as exciplex emission-based white OLEDs are covered in this review.
关键词： organic light-emitting diodes,Exciplexes,thermally activated delayed fluorescence
更新于2025-09-11 14:15:04
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Thulium Laser‐Assisted Versus Conventional Laparoscopic Partial Nephrectomy for the Small Renal Mass
摘要： Mitochondria-targeting cancer therapies have achieved unprecedented advances attributed to their superior ability for improving drug delivery efficiency and producing an enhanced therapeutic effect. Herein, we report a mitochondria-targeting camptothecin (CPT) polyprodrug system (MCPS) covalently decorated with a high-proportioned CPT content, which can realize drug release specifically responsive to a tumor microenvironment. The nonlinear structure of MCPS can form water-soluble unimolecular micelles with high micellar stability and improved drug accumulation in tumoral cells/tissues. Furthermore, a classical mitochondria-targeting agent, triphenylphosphonium bromide, was tethered in this prodrug system, which causes mitochondrial membrane potential depolarization and mediates the transport of CPT into mitochondria. The disulfide bond in MCPS can be cleaved by an intracellular reductant such as glutathione, leading to enhanced destruction of mitochondria DNA and cell apoptosis induced by a high level of reactive oxygen species. The systematic analyses both in vitro and in vivo indicated the excellent tumor inhibition effect and biosafety of MCPS, which is believed to be an advantageous nanoplatform for subcellular organelle-specific chemotherapy of cancer.
关键词： chemotherapy,reduction-activated,mitochondria-targeted,polyprodrug,cancer therapy
更新于2025-09-11 14:15:04