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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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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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Exciplex-forming derivatives of 2,7-di-tert-butyl-9,9-dimethylacridine and benzotrifluoride for efficient OLEDs
摘要： Strongly medium dependent capability to exhibit not only prompt/delayed thermally-activated fluorescence but also aggregation-induced phosphorescence or exciplex emission is demonstrated either for solutions or for solid samples of acridan-based luminophores. Multicolour emissions of different nature were detected and studied for donor-acceptor derivatives of 2- or 4-(trifluoromethyl)benzene and 2,7-di-tert-butyl-9,9-dimethylacridine containing trifluoromethyl groups in ortho and para positions. For the demonstration of one of possible applications, both compounds were tested in the emissive layers of exciplex-based OLEDs. In the best case, their high maximum current, power and external quantum efficiences of 29.5 cd/A, 29.1 lm/W and 8.2 % respectively were achieved for the device based on exciplex electroluminescence resulting from recombination of intermolecular charge transfer states formed on the interface of electron-donating and electron-accepting molecules used.
关键词： exciplex,acridan,thermally activated delayed fluorescence,room temperature phosphorescence,OLED
更新于2025-09-11 14:15:04
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Highly efficient TADF OLEDs with low efficiency roll-off based on novel acridine–carbazole hybrid donor-substituted pyrimidine derivatives
摘要： Dimethyl acridine (Ac) and carbazole (Cz) donors are fused to produce acridine–carbazole hybrid donors, 12AcCz (8,8-dimethyl-5-phenyl-8,13-dihydro-5H-indolo[2,3-c]acridine) and 23AcCz (13,13-dimethyl-7-phenyl-7,13-dihydro-5H-indolo[3,2-b]acridine). By combining TPPM (2,4,6-triphenylpyrimidine) acceptor with the Ac–Cz-fused donors of 12AcCz and 23AcCz, two emitters, 12AcCz-PM (13-(4-(2,6-diphenylpyrimidin-4-yl)phenyl)-8,8-dimethyl-5-phenyl-8,13-dihydro-5H-indolo[2,3-c]acridine) and 23AcCz-PM (5-(4-(2,6-diphenylpyrimidin-4-yl)phenyl)-13,13-dimethyl-7-phenyl-7,13-dihydro-5H-indolo[3,2-b]acridine), are designed and synthesized. The impact of the different fused topologies of the hybrid donors on molecular configuration, photophysical and optoelectrical characters are systematically investigated. For 12AcCz-PM, the large steric hindrance between donor and acceptor compels Ac of 12AcCz to be crooked, which endows it with the relatively planar quasi-axial conformation. No blatant TADF character is observed, but the 12AcCz-PM doped device still presents the ultradeep blue emission with CIEx, y of (0.15, 0.05) and maximum external quantum efficiency (EQEmax) of 6.4%. Whereas, 23AcCz-PM shows quasi-equatorial conformation and possesses notable TADF behavior. The 23AcCz-PM doped device reachs the EQEmax of 28.4% at low dopant concentration and 26.1% at high dopant concentration. Additionally, low efficiency roll-off (EQEs of 24.8% at 1000 cd m-2 and 20.7% at 5000 cd m-2) further confirms its superiorities as a TADF emitter.
关键词： novel acridine–carbazole hybrid donors,highly efficient TADF OLEDs,low efficiency roll-off,thermally activated delayed fluorescence
更新于2025-09-11 14:15:04
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Understanding Solid-State Solvation-Enhanced Thermally Activated Delayed Fluorescence Using a Descriptor-Tuned Screened Range-Separated Functional
摘要： An efficient computational protocol suitable for both solutions and solid films can accelerate the development of efficient thermally activated delayed fluorescence (TADF) emitters aimed at practical application in organic light-emitting diodes (OLEDs). By employing the localized orbital locator (LOL), we establish an efficient descriptor-tuning methodology for the range-separated (RS) and screened range-separated (SRS) functionals with only one single-point calculation. This scheme provides good predictions for 28 charge transfer (CT)-type TADF emitters. Moreover, in comparison to the experimental data, the scheme presents a mean absolute deviation of 0.09 eV for the absorption energies of the lowest excited singlet state (EVA(S1)) in polarizable continuum model (PCM) solution and 0.10 eV for the energy difference between the lowest excited singlet and triplet states (ΔEST) under static solid-state polarization. Importantly, our results indicate that a significantly polarized S1 is key to realizing the so-called solid-state solvation-enhanced (SSSE)-TADF, which is well captured through the screened RS functionals combined with LOL-tuning (SLOL-tuning). Compared with standard ionization potential (IP)-tuning, our scheme significantly reduces the computational cost of the prediction of singlet- and triplet-transition energies for CT molecules. It also provides a reliable approach to evaluate the practical TADF character influenced by solid-state solvation in amorphous organic thin films.
关键词： Thermally Activated Delayed Fluorescence,Optical,Solid-State Solvation-Enhanced,Plasmonics,Magnetic,Hybrid Materials,TADF,Range-Separated Functional,LOL-tuning,OLEDs
更新于2025-09-11 14:15:04
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High-triplet-level phthalimide based acceptors for exciplexes with multicolor emission
摘要： To provide high exciton utilization in organic light emitting diodes, phthalimide derivatives were designed and synthesized as exciplex-forming materials. Due to high triplet levels (2.92-3.11 eV) and ionization potentials (7.18-7.29 eV), the developed phthalimide derivatives were found to be not only appropriate accepting materials for the formation of different color exciplexes but also as bifunctional materials with a satisfactory hole and exciton-blocking abilities. Solid-state blends of the synthesized phthalimides as acceptors and a carbazole containing donors showed exciplex emission. Bimolecular blends exhibited multicolor exciplex emission which covered a visible spectrum from sky-blue to red colors, depending on the donor used. However, the photoluminescence quantum efficiencies of the studied exciplex-forming systems were found to be sensitive to the molecular design of the phthalimides. Acceptor with para- substituted phthalimide showed better exciplex-forming properties in comparison to other compounds. Exciplex-forming blend of (2-(4-benzoylphenyl)isoindoline-1,3-dione) as an acceptor and 1,3-di(9H-carbazol-9-yl)benzene (mCP) as a donor showed the most efficient sky-blue emission with small singlet-triplet splitting (0.06±0.03eV). Such exciplex-forming molecular mixture was implemented as the light-emitting material in the sky-blue organic light emitting diodes which showed the brightness of 2500 cd m-2 and maximum external quantum efficiency of 2.9 % due to the employment of both singlet and triplet excitons.
关键词： exciplex,phthalimide,acceptors,organic light emitting diode (OLED),thermally activated delayed fluorescence (TADF)
更新于2025-09-10 09:29:36