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1.
Mina Jung Kyung Hyung Lee Prof. Dr. Jun Yeob Lee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(21):4816-4821
Benzofurocarbazole moieties are commonly used donor structures in the design of thermally activated delayed fluorescence (TADF) emitters. However, only 5 H-benzofuro[3,2-c]carbazole (34BFCz) has been reported and, to the best of our knowledge, no other benzofurocarbazole derivatives have been covered in the literature. In the present study, two further benzofurocarbazole moieties, 12 H-benzofuro[3,2-a]carbazole (12BFCz) and 7 H-benzofuro[2,3-b]carbazole (23BFCz), have been synthesized to investigate the effect of the donor structure on the photophysics and device parameters of TADF emitters. Two benzofurocarbazole-derived TADF emitters, 12-(2-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-12 H-benzofuro[3,2-a]carbazole (o12BFCzTrz) and 7-(2-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-7 H-benzofuro[2,3-b]carbazole (o23BFCzTrz), have been compared with 5-(2-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-5 H-benzofuro[3,2-c]carbazole (oBFCzTrz). The benzofurocarbazole donor structure governs the TADF characteristics, such as charge-transfer property and emission color. The 12BFCz donor has proved to be effective in blue-shifting the emission color, and 34BFCz has proven useful for improving the external quantum efficiency (EQE). The 12BFCz-derived o12BFCzTrz showed blue-shifted color coordinates of (0.159, 0.288), compared to (0.178, 0388) for o23BFCzTrz and (0.169, 0.341) for oBFCzTrz. The 34BFCz-derived oBFCzTrz exhibited an EQE of 22.9 %, compared to 19.2 % for o12BFCzTrz and 21.1 % for o23BFCzTrz. 相似文献
2.
Yiyu Yang Ran Xiao Xiaosong Cao Zhanxiang Chen Xialei Lv Youming Zhang Shaolong Gong Yang Zou Chuluo Yang 《Molecules (Basel, Switzerland)》2021,26(17)
In this work, we demonstrate dibenzothiophene sulfoximine derivatives as building blocks for constructing emitters featuring both thermally activated delayed fluorescent (TADF) and aggregation-induced emission (AIE) properties, with multiple advantages including high chemical and thermal stability, facile functionalization, as well as tunable electron-accepting ability. A series of phenoxazine-dibenzothiophene sulfoximine structured TADF emitters were successfully synthesized and their photophysical and electroluminescent properties were evaluated. The electroluminescence devices based on these emitters displayed diverse emissions from yellow to orange and reached external quantum efficiencies (EQEs) of 5.8% with 16.7% efficiency roll-off at a high brightness of 1000 cd·m−2. 相似文献
3.
Hsin-Yun Chih Ying-Wei Chen Yi-Chun Hsieh Wei-Cheng Li Chia-Wei Liao Chun-Han Lin Ting-Ya Chiu Dr. Wei-Wen Tsai Dr. Chin-Wei Lu Dr. Chih-Hao Chang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(72):16699-16711
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 layers (EMLs). 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 the 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 EMLs showed satisfactory efficiencies of 12.8 % and 15.8 %, respectively, which is one of the highest external quantum efficiency (EQEs) reported for blue TADF emitters (λpeak<475 nm), demonstrating that our tailored molecular designs are promising strategies to endow OLEDs with excellent electroluminescent performances. 相似文献
4.
Tingting Huang Prof. Dr. Di Liu Prof. Dr. Jingyang Jiang Prof. Dr. Wenfeng Jiang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(46):10926-10937
Quinoxaline (Q), pyrido[2,3-b]pyrazine (PP) and pyrido[3,4-b]pyrazine (iPP) are used as electron acceptors (A) to design a series of D–π–A-type light-emitting materials with different donor (D) groups. By adjusting the molecular torsion angles through changing D from carbazole (Cz) to 10-dimethylacridine (DMAC) or 10H-phenoxazine (PXZ) for a fixed A, the luminescence is tuned from normal fluorescence to thermally activated delayed fluorescence (TADF). By gradually enhancing the intramolecular charge-transfer extent through combining different D and A, the emission color is continuously and regularly tuned from pure blue to orange–red. Organic light-emitting diodes (OLEDs) containing these compounds as doped emitters exhibit bright electroluminescence with emission colors covering the entire visible-light range. An external quantum efficiency (ηext) of 1.2 % with excellent color coordinates of (0.16, 0.07) is obtained for the pure-blue OLED of Q-Cz. High ηext values of 12.9 (35.9) to 16.7 % (51.9 cd A−1) are realized in the green, yellow, and orange–red TADF OLEDs. All PP- and iPP-based TADF emitters exhibit superior efficiency stabilities to that of analogues of Q. This provides a practical strategy to tune the emission color of Q, PP, and iPP derivatives with the same molecular skeletons over the entire visible-light range. 相似文献
5.
Three sets of conjugated polymers with backbone‐donor/pendant‐acceptor architectures, named PCzA3PyB, PCzAB2Py, and PCzAB3Py, are designed and synthesized. The three isomeric benzoylpyridine‐based pendant acceptor groups are 6‐benzoylpyridin‐3‐yl (3PyB), 4‐((pyridin‐2‐yl)carbonyl)phenyl (B2Py) and 4‐((pyridin‐3‐yl)carbonyl)phenyl (B3Py), whereas the identical backbone consists of 3,6‐carbazolyl and 2,7‐acridinyl rings. One acridine ring and each acceptor group constitute a definite thermally activated delayed fluorescence (TADF) unit, incorporated into the main chain of the polymers through the 2,7‐position of the acridine ring with the varied content. All of the polymers display legible TADF features with a short microsecond‐scale delayed lifetime (0.56–1.62 μs) and a small singlet/triplet energy gap (0.10–0.19 eV). Progressively redshifted emissions are observed in the order PCzAB3Py, PCzA3PyB, and PCzAB2Py owing to the different substitution patterns of the pyridyl group. Photoluminescence quantum yields can be improved by regulating the molar content of the TADF unit in the range 0.5–50 %. The non‐doped organic light‐emitting devices (OLEDs) fabricated by solution‐processing technology emit yellow‐green to orange light. The polymers with 5 mol % of the TADF unit exhibit excellent comprehensive electroluminescence performance, in which PCzAB2Py5 achieves a maximum external quantum efficiency (EQE) of 11.9 %, low turn‐on voltage of 3.0 V, yellow emission with a wavelength of 573 nm and slow roll‐off with EQE of 11.6 % at a luminance of 1000 cd m?2 and driving voltage of 5.5 V. 相似文献
6.
Shantaram Kothavale Kyung Hyung Lee Prof. Jun Yeob Lee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(4):845-852
Two efficient thermally activated delayed fluorescent (TADF) emitters were developed by utilizing CN-modified imidazopyridine as an acceptor unit. The CN-modified imidazopyridine acceptor was combined with either an acridine donor or a phenoxazine donor through a phenyl linker to produce two TADF emitters, Ac-CNImPy and PXZ-CNImPy. The acridine-based Ac-CNImPy emitter exhibited sky-blue emission with a CIE coordinate of (0.18, 0.38), whereas the phenoxazine-donor-based PXZ-CNImPy showed greenish-yellow emission with a CIE coordinate of (0.32, 0.58). A high photoluminescence quantum yield of 80 % was observed for the PXZ-CNImPy emitter compared with 40 % for the Ac-CNImPy emitter. Organic light-emitting diodes based on the PXZ-CNImPy emitter demonstrated high external quantum efficiency of 17.0 %. Hence, the CN-modified imidazopyridine unit can be considered as a useful electron acceptor for the future design of highly efficient TADF emitters. 相似文献
7.
Recently, pure organic thermally activated delayed fluorescence (TADF) emitters have attracted considerable interest from the scientific community in the field of organic light emitting diodes (OLEDs) as they can theoretically realize 100 % of the internal quantum efficiency by exploiting both the singlet and triplet excitons via the reverse intersystem crossing enabled by small singlet‐triplet energy splitting. Currently, the external quantum efficiency of the TADF emitters is reaching the level of phosphorescent emitters. Therefore, the TADF approach is considered as a potential alternative to the low efficiency conventional fluorescent and expensive phosphorescent emitters. In this account, we summarized our recent development of blue and green TADF molecular designs to improve the device performances of the TADF devices. 相似文献
8.
Lin He Xuan Zeng Weimin Ning Ao Ying Yunbai Luo Shaolong Gong 《Molecules (Basel, Switzerland)》2021,26(9)
How to construct efficient red-emitting thermally activated delayed fluorescence (TADF) materials is a challenging task in the field of organic light-emitting diodes (OLEDs). Herein, an electron acceptor moiety, 3,6-DCNB-DPPZ, with high rigidity and strong acceptor strength was designed by introducing two cyanobenzene groups into the 3,6-positions of a dipyrido[3,2-a:2′,3′-c]phenazine unit. A red-emitting compound, 3,6_R, has been designed and synthesized by combining the rigid acceptor unit with two triphenylamine donors. Due to high molecular rigidity and strong intramolecular charge transfer characteristic in donor–acceptor–donor skeleton, 3,6_R exhibited a red emission with a high photoluminescence quantum yield of 86% and distinct TADF nature with short delayed fluorescence lifetime of about 1 microsecond. Accordingly, the OLED using 3,6_R as the guest emitter gained a high external quantum efficiency of 12.0% in the red region with an electroluminescence peak of 619 nm and favorable Commission Internationale de l’Eclairage coordinates of (0.62, 0.38). 相似文献
9.
Dr. Chan Seok Oh Ha Lim Lee Si Hyun Han Prof. Jun Yeob Lee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(2):642-648
Blue thermally activated delayed fluorescent (TADF) devices with short excited-state lifetime, high reverse intersystem crossing rate, and low-efficiency roll-off were developed by managing the molecular structure of donor–acceptor-type blue emitters. Three isomers of blue TADF emitters with a diphenyltriazine acceptor and three carbazole donors were synthesized. The position of the donor moieties in the phenyl linker connecting the donor and acceptor moieties was controlled to devise compounds with a short delayed fluorescence lifetime. A blue TADF emitter with three carbazole donors at 2-, 3-, and 4- positions of a phenyl linker shortened the excited state lifetime to 4.1 μs, showed a high external quantum efficiency of 20.4 %, and low efficiency roll-off of less than 10 % at 1000 cd m−2. Therefore, a molecular design distorting the donors by aligning them in a consecutive way is useful to resolve the issues of long delayed fluorescence lifetime and efficiency roll-off of blue TADF devices. 相似文献
10.
Ji Han Kim Kyung Hyung Lee Prof. Dr. Jun Yeob Lee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(38):9060-9070
Organic light-emitting diodes are currently under research to achieve high efficiency and long life by using thermally activated delayed fluorescence (TADF) materials. In particular, many studies have focused on ensuring high efficiency in fluorescent devices by introducing TADF materials. Herein, four kinds of orange-colored TADF materials were synthesized and introduced into 5,10,15,20-tetraphenylbisbenz[5,6]indeno[1,2,3-cd:1′,2′,3′-lm]perylene (DBP) red fluorescent devices as assistant dopants. These TADF materials assisted in achieving high efficiency in DBP devices by reducing nonradiative process by Dexter energy transfer and harvesting singlet excitons by a Förster resonance energy transfer process. Among the four TADF materials, 2-(3,5-di-tert-butylphenyl)-6-(9,9-diphenylacridin-10(9H)-yl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (DtBIQAP) showed a higher reverse intersystem crossing rate and a smaller nonradiative rate constant than the other two materials, which can reduce the exciton loss process. As a result, the DtBIQAP-assisted DBP device showed a high maximum external quantum efficiency of 18.2 % and color coordinates of (0.63, 0.37) in red fluorescent organic light-emitting diodes. This study provided a strategy of developing assistant dopants for high external quantum efficiency in TADF-assisted fluorescent devices. 相似文献
11.
A Methodological Study on Tuning the Thermally Activated Delayed Fluorescent Performance by Molecular Constitution in Acridine–Benzophenone Derivatives
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Rongjuan Yang Qian Guan Zhiyang Liu Wei Song Ling Hong Tao Lei Qiang Wei Ruixiang Peng Xi Fan Prof. Ziyi Ge 《化学:亚洲杂志》2018,13(9):1187-1191
Thermally activated delayed fluorescent (TADF) emitters are usually designed as donor–acceptor structures with large dihedral angles, which tend to incur low fluorescent efficiency, and therefore, through molecular design various strategies have been proposed to increase the efficiency of emitters; however, few studies have compared these strategies in one TADF system. In this study, a novel TADF molecule, [4‐(9,9‐diphenylacridin‐10‐yl)phenyl](phenyl)methanone ( BP‐DPAC ), was designed as a prototype, and two derivatives, BP‐Ph‐DPAC and DPAC‐BP‐DPAC , were also prepared to represent two common approaches to enhance TADF performance. Compared with the maximum external quantum efficiency (EQE) of 6.82 % for BP‐DPAC , organic light‐emitting diodes (OLED) devices based on DPAC‐BP‐DPAC exhibited enhanced TADF properties with the highest maximum EQE of 18.67 %, owing to an additional diphenylacridine donor, whereas BP‐Ph‐DPAC showed non‐TADF properties and exhibited the lowest EQE of 4.25 %, owing to the insertion of a phenyl ring between donor and acceptor. 相似文献
12.
Min Gyeong Choi Chan Hee Lee Chihaya Adachi Sae Youn Lee 《Molecules (Basel, Switzerland)》2022,27(23)
In this study, we developed two thermally activated delayed fluorescence (TADF) emitters, ICzCN and ICzCYP, to apply to organic light-emitting diodes (OLEDs). These emitters involve indolocarbazole (ICz) donor units and nicotinonitrile acceptor units with a twisted donor-acceptor-donor (D-A-D) structure for small singlet (S1) and triplet (T1) state energy gap (ΔEST) to enable efficient exciton transfer from the T1 to the S1 state. Depending on the position of the cyano-substituent, ICzCN has a symmetric structure by introducing donor units at the 3,5-position of isonicotinonitrile, and ICzCYP has an asymmetric structure by introducing donor units at the 2,6-position of nicotinonitrile. These emitters have different properties, such as the maximum luminance (Lmax) value. The Lmax of ICzCN reached over 10000 cd m−2. The external quantum efficiency (ηext) was 14.8% for ICzCN and 14.9% for ICzCYP, and both achieved a low turn-on voltage (Von) of less than 3.4 eV. 相似文献
13.
Lei Cao Shiqing Huang Wei Liu Hongyan Zhao Prof. Xiao-Gen Xiong Prof. Jian-Ping Zhang Prof. Li-Min Fu Prof. Xiaoyu Yan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(71):17222-17229
A series of two-coordinate AuI and CuI complexes ( 3 a , 3 b and 5 a , 5 b ) are reported as new organometallic thermally activated delayed fluorescence (TADF) emitters, which are based on the carbene–metal–carbazole model with a pyridine-fused 1,2,3-triazolylidene (PyTz) ligand. PyTz features low steric hindrance and a low-energy LUMO (LUMO=−1.47 eV) located over the π* orbitals of the whole ligand, which facilitates intermolecular charge transfer between a donor (carbazole) and an accepter (PyTz). These compounds exhibit efficient TADF with microsecond lifetimes. Temperature-dependent photoluminescence kinetics of 3 a supports a rather small energy gap between S1 and T1 (ΔE =60 meV). Further experiments reveal that there are dual-emission properties from a monomer–dimer equilibrium in solution, exhibiting single-component multicolor emission from blue to orange, including white-light emission. 相似文献
14.
聚合物热激活延迟荧光(TADF)材料应用于有机发光二极管(OLEDs)中以来,取得了飞速发展,迄今为止已经报道了多种不同分子结构及性能优异的聚合物TADF发光材料.它们具有不含重金属的化学结构、100%的理论内量子效率和易于通过溶液加工进行大面积制造的优势.本文从分子结构和发光颜色2个角度总结了不同结构TADF聚合物的研究进展,重点介绍了我们课题组在长链型TADF聚合物设计与OLEDs器件性能方面的研究工作,探究TADF聚合物颜色调控与效率提升的途径,论述了TADF聚合物存在的问题与未来发展. 相似文献
15.
Molecular Orbital Controlling Donor Moiety for High‐Efficiency Thermally Activated Delayed Fluorescent Emitters
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A new donor moiety, 7,7,13,13‐tetramethyl‐7,13‐dihydro‐5H‐indeno[1,2‐b]acridine (IAc), was developed to control the highest occupied molecular orbital (HOMO) dispersion of thermally activated delayed fluorescent (TADF) emitters. The IAc unit expanded the HOMO dispersion of the emitters and increased the quantum efficiency of the TADF devices up to 20.9 %. 相似文献
16.
Hiroki Arai Prof. Hisahiro Sasabe Hisaki Tsuneyama Kengo Kumada Prof. Junji Kido 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(42):10869-10874
Recently, researchers have focused on thermally activated delayed fluorescence (TADF) for efficient future lighting and displays. Among TADF emitters, a combination of triazine and acridine is a promising candidate for realizing high-efficiency organic light-emitting devices (OLEDs). However, simultaneous development of perfect horizontal orientation (Θ=100 %) and an external quantum efficiency (EQE) of over 40 % is still challenging. Here, to obtain insights for further improvements of a triazine/acridine combination, various asymmetric spirobiacridine (SBA)-based TADF emitters with a unity photoluminescence quantum yield and high Θ ratio of over 80 % were developed. Furthermore, the substitution effects of the triazine acceptor unit on the photophysical properties were studied, including molecular orientations and OLED performance. The corresponding OLED exhibited sky-blue emission with a high EQE of over 30 %. 相似文献
17.
Sung Joon Yoon Ji Han Kim Won Jae Chung Prof. Jun Yeob Lee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(9):3065-3073
In this work, a design approach of three thermally activated delayed fluorescence (TADF) emitters to extend the device lifetime of the TADF sensitized fluorescent devices was studied. Three TADF materials, 5-{4,6-bis[4-(tert-butyl)phenyl]-1,3,5-triazin-2-yl}-2-(10,15-diphenyl-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazol-5-yl)benzonitrile (tTCNTruX), 4-[3-cyano-4-(10,15-diphenyl-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazol-5-yl)phenyl]-2,6-diphenylpyrimidine-5-carbonitrile (PCNTruX) and 4-(4-{10,15-bis[4-(tert-butyl)phenyl]-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazol-5-yl}-3-cyanophenyl)-2,6-diphenylpyrimidine-5-carbonitrile (PCNtTruX), were synthesized as sensitizers for TADF-sensitized fluorescent organic light-emitting diodes. The two tTCNTruX and PCNtTruX TADF emitters were designed to have Dexter energy transfer with blocking groups either in the donor or acceptor unit of the donor–acceptor-type TADF sensitizer. The TADF materials showed small singlet–triplet energy splitting and a high reverse intersystem crossing (RISC) rate for effective sensitization of the fluorescent emission of the fluorescent emitter. tTCNTruX- and PCNtTruX-sensitized fluorescent devices showed maximum external quantum efficiencies (EQEs) of 17.7 % and 11.5 % in the yellow and red devices, respectively, which were higher than those of TADF-sensitized devices with the corresponding TADF sensitizer without a blocking group. Moreover, the device lifetime was also extended by employing the tTCNTruX and PCNtTruX sensitizers. This work demonstrated that the tTCNTruX and PCNtTruX sensitizers are effective to improve the maximum EQE and device lifetime of TADF-sensitized fluorescent devices. 相似文献
18.
Intermolecular Charge‐Transfer Transition Emitter Showing Thermally Activated Delayed Fluorescence for Efficient Non‐Doped OLEDs
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Yi‐Zhong Shi Kai Wang Xing Li Gao‐Le Dai Wei Liu Ke Ke Ming Zhang Prof. Si‐Lu Tao Prof. Cai‐Jun Zheng Prof. Xue‐Mei Ou Prof. Xiao‐Hong Zhang 《Angewandte Chemie (International ed. in English)》2018,57(30):9480-9484
A novel molecular model of connecting electron‐donating (D) and electron‐withdrawing (A) moieties via a space‐enough and conjugation‐forbidden linkage (D‐Spacer‐A) is proposed to develop efficient non‐doped thermally activated delayed fluorescence (TADF) emitters. 10‐(4‐(4‐(4,6‐diphenyl‐1,3,5‐triazin‐2‐yl) phenoxy) phenyl)‐9,9‐dimethyl‐9,10‐dihydroacridine (DMAC‐o‐TRZ) was designed and synthesized accordingly. As expected, it exhibits local excited properties in single‐molecule state as D‐Spacer‐A molecular backbone strongly suppress the intramolecular charge‐transfer (CT) transition. And intermolecular CT transition acted as the vital radiation channel for neat DMAC‐o‐TRZ film. As in return, the non‐doped device exhibits a remarkable maximum external quantum efficiency (EQE) of 14.7 %. These results prove the feasibility of D‐Spacer‐A molecules to develop intermolecular CT transition TADF emitters for efficient non‐doped OLEDs. 相似文献
19.
Dibenzo[a,j]phenazine‐Cored Donor–Acceptor–Donor Compounds as Green‐to‐Red/NIR Thermally Activated Delayed Fluorescence Organic Light Emitters
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Dr. Przemyslaw Data Piotr Pander Masato Okazaki Prof. Dr. Youhei Takeda Prof. Dr. Satoshi Minakata Prof. Dr. Andrew P. Monkman 《Angewandte Chemie (International ed. in English)》2016,55(19):5739-5744
A new family of thermally activated delayed fluorescence (TADF) emitters based on U‐shaped D‐A‐D architecture with a novel accepting unit has been developed. All investigated compounds have small singlet‐triplet energy splitting (ΔEST) ranging from 0.02 to 0.20 eV and showed efficient TADF properties. The lowest triplet state of the acceptor unit plays the key role in the TADF mechanism. OLEDs fabricated with these TADF emitters achieved excellent efficiencies up to 16 % external quantum efficiency (EQE). 相似文献
20.
《化学:亚洲杂志》2017,12(18):2494-2500
Donor–acceptor–donor (D–A–D)‐type thermally activated delayed fluorescence (TADF) emitters 5,5′‐bis{4‐[9,9‐dimethylacridin‐10(9H )‐yl]phenyl}‐2,2′‐bipyrimidine (Ac‐bpm) and 5,5′‐bis[4‐(10H ‐phenoxazin‐10‐yl)phenyl]‐2,2′‐bipyrimidine (Px‐bpm), based on the 2,2′‐bipyrimidine accepting unit, were developed and their TADF devices were fabricated. The orthogonal geometry between the donor unit and the 2,2′‐bipyrimidine accepting core facilitated a HOMO/LUMO spatial separation, thus realizing thermally activated delayed fluorescence. The exhibited electroluminescence ranged from green to yellow, depending on the donor unit, with maximum external quantum efficiencies of up to 17.1 %. 相似文献