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Effect of aggregation on thermally activated delayed fluorescence and ultralong organic phosphorescence:QM/MM study
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作者 张群 王晓菲 +6 位作者 吴智敏 李小芳 张凯 宋玉志 范建忠 王传奎 蔺丽丽 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第10期410-419,共10页
Aggregation-induced thermally activated delayed fluorescence(TADF)phenomena have attracted extensive attention recently.In this paper,several theoretical models including monomer,dimer,and complex are used for the exp... Aggregation-induced thermally activated delayed fluorescence(TADF)phenomena have attracted extensive attention recently.In this paper,several theoretical models including monomer,dimer,and complex are used for the explanation of the luminescent properties of(R)-5-(9H-carbazol-9-yl)-2-(1,2,3,4-tetrahydronaphthalen-1-yl)isoindoline-1,3-dione((R)-ImNCz),which was recently reported[Chemical Engineering Journal 418129167(2021)].The polarizable continuum model(PCM)and the combined quantum mechanics and molecular mechanics(QM/MM)method are adopted in simulation of the property of the molecule in the gas phase,solvated in acetonitrile and in aggregation states.It is found that large spin–orbit coupling(SOC)constants and a smaller energy gap between the first singlet excited state and the first triplet excited state(△E_(st))in prism-like single crystals(SC_(p)-form)are responsible for the TADF of(R)-lmNCz,while no TADF is found in block-like single crystals(SC_(b)-form)with a larger △E_(st).The multiple ultralong phosphorescence(UOP)peaks in the spectrum are of complex origins,and they are related not only to ImNCz but also to a minor amount of impurities(ImNBd)in the crystal prepared in the laboratory.The dimer has similar phosphorescence emission wavelengths to the(R)-lmNCz-SC_(p) monomers.The complex composed of(R)-lmNCz and(R)-lmNBd contributes to the phosphorescent emission peak at about 600 nm,and the phosphorescent emission peak at about 650 nm is generated by(R)-lmNBd.This indicates that the impurity could also contribute to emission in molecular crystals.The present calculations clarify the relationship between the molecular aggregation and the light-emitting properties of the TADF emitters and will therefore be helpful for the design of potentially more useful TADF emitters. 展开更多
关键词 organic light-emitting diodes thermally activated delayed fluorescence ultralong organic phosphorescence aggregation mode
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First-Principles Investigation on Triazine Based Thermally Activated Delayed Fluorescence Emitters
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作者 范建忠 邱帅 +1 位作者 蔺丽丽 王传奎 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2016年第3期291-296,I0001,共7页
Three kinds of triazine based organic molecules designed for thermally activated delayed fluorescence (TADF) emitters are investigated by first-principles calculations. An optimal Hartree-Fork (HF) method is adopt... Three kinds of triazine based organic molecules designed for thermally activated delayed fluorescence (TADF) emitters are investigated by first-principles calculations. An optimal Hartree-Fork (HF) method is adopted for the calculation of energy gap between the first singlet state (S1) and the first triplet state (T1). The natural transition orbital, the electron- hole (e-h) distribution and the e-h overlap diagram indicate that the S1 states for the three systems include both charge-transfer and some localized excitation component. Further quantitative analysis of the excitation property is performed by introducing the index Ar and the integral of e-h overlap S. It is found that symmetric geometry is a necessary condition for TADF emitters, which can provide more delocalized transition orbitals and consequently a small S1-T1 energy gap. Artful inserting aromatic groups between donors and acceptors can significantly enhance the oscillator strength. Finally, the energy state structures calculated with the optimal HF method is presented, which can provide basis for the study of the dynamics of excited states. 展开更多
关键词 FIRST-PRINCIPLES thermally activated delayed fluorescence Charge-transferstates
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Inuence of Electron Donating Ability on Reverse Intersystem Crossing Rate for One Kind of Thermally Activated Delayed Fluorescence Molecules
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作者 Ming-lang Wang Jian-zhong Fan Li-li Lin 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2018年第3期291-299,367,共10页
First-principles calculations are applied for investigating influence of electron donating ability of donor groups in eight thermally activated delayed fluorescence(TADF) molecules on their geometrical structures an... First-principles calculations are applied for investigating influence of electron donating ability of donor groups in eight thermally activated delayed fluorescence(TADF) molecules on their geometrical structures and transition properties as well as reverse intersystem crossing(RISC) processes. Results show that the diphenylamine substitution in the donor part can slightly change the bond angle but decrease bond length between donor and acceptor unit except for the lowest triplet state(Ti) of carbazole-xanthone molecule. As the electron donating ability of donor groups is increased, the overlap between the highest occupied molecular orbital(HOMO) and the lowest unoccupied molecular orbital(LUMO) is decreased. As the diphenylamine groups are added in donor part, the delocalization of HOMO is enlarged,which brings a decreased energy gap(△ES1-T1) between the lowest singlet excited state(S1)and T1 state. Furthermore, with the calculated spin-orbit coupling coefficient(HSO), one finds that the larger value of ■ is, the faster the RISC is. The results show that all investigated molecules are promising candidates as TADF molecules. Overall, a wise molecular design strategy for TADF molecules,in which a small △ES1-T1 can be achieved by enlarging the delocalization of frontier molecular orbitals with large separation between HOMO and LUMO, is proposed. 展开更多
关键词 thermally activated delayed fluorescence Donating ABILITY REVERSE intersystem CROSSING SPIN-ORBIT coupling
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High Efficiency and Stable Organic Light-Emitting Diodes Based on Thermally Activated Delayed Fluorescence Emitter
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作者 吕孝鹏 王会 +7 位作者 孟令强 魏晓芳 陈永振 孔祥彬 刘建君 唐建新 汪鹏飞 王鹰 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第8期139-142,共4页
High efficiency, stable organic light-emitting diodes (OLEDs) based on 2-pheyl-4'-carbazole-9-H-Thioxanthen-9- one-10, 10-dioxide (TXO-PhCz) with different doping concentration are constructed. The stability of t... High efficiency, stable organic light-emitting diodes (OLEDs) based on 2-pheyl-4'-carbazole-9-H-Thioxanthen-9- one-10, 10-dioxide (TXO-PhCz) with different doping concentration are constructed. The stability of the encap- sulated devices are investigated in detail. The devices with the 10 wt% doped TXO-PhCz emitter layer (EML) show the best performance with a current efficiency of 52.1 cd/A, a power efficiency of 32.71re^W, and an external quantum efficiency (EQE) of 17.7%. The devices based on the lOwt%-doped TXO-PhCz EML show the best operational stability with a half-life time (LTSO) of 8Oh, which is 8 h longer than that of the reference devices based on fac-tris(2-phenylpyridinato)iridium( Ⅲ) (Ir(ppy)a). These indicate excellent stability of TXO-PhCz for redox and oxidation processes under electrical excitation and TXO-PhCz can be potentially used as the emitters for OLEDs with high efficiency and excellent stability. The high-performance device based on TXO-PhCz with high stability can be further improved by the optimization of the encapsulation technology and the development of a new host for TXO-PhCz. 展开更多
关键词 OLEDs in of High Efficiency and Stable Organic Light-Emitting Diodes Based on thermally activated delayed fluorescence Emitter EML on for
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Theoretical verification of intermolecular hydrogen bond induced thermally activated delayed fluorescence in SOBF-OMe
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作者 Mu-Zhen Li Fei-Yan Li +5 位作者 Qun Zhang Kai Zhang Yu-Zhi Song Jian-Zhong Fan Chuan-Kui Wang Li-Li Lin 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第12期378-384,共7页
Thermally activated delayed fluorescence(TADF)molecules have attracted great attention as high efficient luminescent materials.Most of TADF molecules possess small energy gap between the first singlet excited state(S_... Thermally activated delayed fluorescence(TADF)molecules have attracted great attention as high efficient luminescent materials.Most of TADF molecules possess small energy gap between the first singlet excited state(S_(1))and the first triplet excited state(T_(1))to favor the up-conversion from T_(1)to S_(1).In this paper,a new TADF generation mechanism is revealed based on theoretical simulation.By systematic study of the light-emitting properties of SOBF-OMe in both toluene and in aggregation state,we find that the single SOBF-OMe could not realize TADF emission due to large energy gap as well as small up-conversion rates between S_(1)and T_(1).Through analysis of dimers,we find that dimers with intermolecular hydrogen bond(H-bond)are responsible for the generation of TADF,since smaller energy gap between S_(1)and T_(1)is found and the emission wavelength is in good agreement with experimental counterpart.The emission properties of SOBF-H are also studied for comparison,which reflect the important role of H-bond.Our theoretical results agree ith experimental results well and confirm the mechanism of H-bond induced TADF. 展开更多
关键词 organic light-emitting diodes thermally activated delayed fluorescence intermolecular hydrogen bond decay rates
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Luminescent properties of thermally activated delayed fluorescence molecule with intramolecular π-π interaction between donor and acceptor
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作者 蔡磊 范建忠 +2 位作者 孔祥朋 蔺丽丽 王传奎 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第11期544-549,共6页
Influence of intramolecular π-π interaction on the luminescent properties of thermally activated delayed fluorescence(TADF) molecule(3, 5-bis(3,6-di-tert-butyl-9 H-carbazol-9-yl)-phenyl)(pyridin-4-yl) methan... Influence of intramolecular π-π interaction on the luminescent properties of thermally activated delayed fluorescence(TADF) molecule(3, 5-bis(3,6-di-tert-butyl-9 H-carbazol-9-yl)-phenyl)(pyridin-4-yl) methanone(DTCBPY) is theoretically studied by using the density functional theory(DFT) and time-dependent density functional theory(TD-DFT).Four conformations(named as A, B, C, and D) of the DTCBPY can be found by relax scanning, and the configuration C corresponds to the luminescent molecule detected experimentally. Besides, we calculate the proportion of each conformation by Boltzmann distribution, high configuration ratios(44% and 52%) can be found for C and D. Moreover, C and D are found to exist with an intramolecular π-π interaction between one donor and the acceptor; the intramolecular interaction brings a smaller Huang-Rhys factor and reduced reorganization energy. Our work presents a rational explanation for the experimental results and demonstrates the importance of the intramolecular π-π interaction to the photophysical properties of TADF molecules. 展开更多
关键词 thermally activated delayed fluorescence intramolecular π-π interaction Huang-Rhys factor and reorganization energy aggregation induced enhanced emission
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A modular approach to efficient thermally activated delayed fluorescence from metal-perturbed intraligand charge-transfer excited state of Au(Ⅰ)complexes
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作者 Jian-Gong Yang Xingyu Feng +7 位作者 Guohua Xie Nengquan Li Jiayu Li Xiu-Fang Song Ming-De Li Jingling Zhang Xiaoyong Chang Kai Li 《Science China Chemistry》 SCIE EI CAS CSCD 2024年第12期4149-4157,共9页
The efficient harvesting of triplet excitons is crucial to the realization of high-performance organic light-emitting diodes(OLEDs).Herein,we show that coordination of donor-acceptor(D-A)type molecules to a metal atom... The efficient harvesting of triplet excitons is crucial to the realization of high-performance organic light-emitting diodes(OLEDs).Herein,we show that coordination of donor-acceptor(D-A)type molecules to a metal atom in a monodentate fashion can lead to thermally activated delayed fluorescence(TADF)emissions with wide color tunability only through varying the noncoordinating acceptor moiety.A panel of TADF gold(Ⅰ)complexes with emission maxima(λmax)of 545–645 nm from metal perturbed intraligand charge-transfer(MPICT)excited states have been developed.Synergetic effects of heavy atom-induced spin-orbit coupling(SOC),steric-induced donor-acceptor twisting and suppressed intramolecular motions lead to high emission efficiencies of 65%-85%in doped films with delayed fluorescence lifetime of as short as 2.0μs.Transient absorption spectroscopic studies on selected complexes determined the kISCto be 6.5×10^(9)s^(-1).Theoretical calculations confirmed the participation of minor d orbital into the lowest excited state,which led to an SOC value of 5.19 cm^(-1)between the lowest-lying singlet and triplet excited states.The yellow to deep red solution-processed OLEDs based on the new gold(Ⅰ)complexes incorporated with various D-A ligands demonstrated promising performances.This study validates a modular design for TADF metal complexes,which will broaden the choices of metal centers and allow for facile color tuning via simple ligand synthesis. 展开更多
关键词 gold(Ⅰ)complex OLED thermally activated delayed fluorescence(tadf) MPICT
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Thermally activated delayed fluorescence carbazole-triazine dendrimer with bulky substituents
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作者 Hiroki Ikebe Kohei Nakao +7 位作者 Eri Hisamura Minori Furukori Yasuo Nakayama Takuya Hosokai Minlang Yang Guanting Liu Takuma Yasuda Ken Albrecht 《Aggregate》 EI CAS 2024年第1期236-243,共8页
Carbazole-triazine dendrimers with a bulky terminal substituent were synthesized,and the thermally activated delayed fluorescence(TADF)property was investigated.Compared to unsubstituted carbazole dendrimers,dendrimer... Carbazole-triazine dendrimers with a bulky terminal substituent were synthesized,and the thermally activated delayed fluorescence(TADF)property was investigated.Compared to unsubstituted carbazole dendrimers,dendrimers with bulky terminal substituents showed comparable to better photoluminescence quantum yields(PLQY)in neat films.Phenylfluorene(PF)-substituted dendrimers showed the highest PLQY of 81%,a smallΔEst of 0.06 eV,and the fastest reverse intersystem crossing(RISC)rate of∼1×10^(5 )s^(−1) compared to other dendrimers.Phosphorescence measurements of dendrimers and dendrons(fragments)indicate that the close proximity of the triplet energy of phenylfluorene-substituted carbazole dendrons(^(3)LE)to that of phenylfluorene-substituted dendrimers(^(1)CT,^(3)CT)contributes to RISC promotion and improves TADF efficiency.Terminal modification fine-tunes the energy level and suppresses intermolecular interactions,and this study provides a guideline for designing efficient solution-processable and non-doped TADF materials. 展开更多
关键词 DENDRIMER OLED tadf 1 INTRODUCTION thermally activated delayed materials which are inexpensive and highly efficient alternatives to fluorescent
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Heptagonal intramolecular-lock strategy enables high-performance thermally activated delayed fluorescence emitters
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作者 Zhenmei Huang Dezhi Yang +2 位作者 Dongge Ma Zhengyang Bin Jingsong You 《Science China Chemistry》 SCIE EI CAS CSCD 2024年第4期1181-1186,共6页
The development of highly efficient thermally activated delayed fluorescence(TADF)emitters is persistently pursued for the application of organic light-emitting diodes(OLED)in full-colour display and solid-state light... The development of highly efficient thermally activated delayed fluorescence(TADF)emitters is persistently pursued for the application of organic light-emitting diodes(OLED)in full-colour display and solid-state lighting.Herein,we present a heptagonal intramolecular-lock strategy to design high-performance TADF emitters.As a proof-of-concept,a new type of tribenzotropone(TBP)acceptor has been designed and synthesized by a cascade decarboxylative cyclization of aryl oxoacetic acid derivative with biphenyl boronic acid.Compared with the unlocked benzophenone(BP)acceptor,the TBP acceptor has a highly twisted heptagonal geometry with moderate rigidity and flexibility,which enables a high-performance TADF emitter with a small single-triplet energy gap(ΔE_(ST))of 0.04 e V,a high photoluminescence quantum yield(Φ_(PL))of 99% and a large horizontal orientation factor(Θ_(//))of 84.0%.Consequently,highly efficient OLEDs with an external quantum efficiency as high as 33.8% are assembled,which is significantly higher than those of DPAC-BP with a highly rotatable BP acceptor(23.8%)as well as DPACFO with a rigid fluorenone(FO)acceptor(6.9%). 展开更多
关键词 organic light-emitting diodes medium-ring intramolecular-lock thermally activated delayed fluorescence molecular orientation
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Supramolecular Thermally Activated Delayed Fluorescence Materials via Through-Space Charge Transfer
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作者 Yuqian Wang Ruicong Feng +1 位作者 Yang Yu Qiao Song 《CCS Chemistry》 CSCD 2024年第5期1165-1173,共9页
Thermally activated delayed fluorescence(TADF)polymeric materials based on through-space charge transfer(TSCT)have emerged as a highly studied topic in recent years.However,the construction of TSCT TADF materials via ... Thermally activated delayed fluorescence(TADF)polymeric materials based on through-space charge transfer(TSCT)have emerged as a highly studied topic in recent years.However,the construction of TSCT TADF materials via a supramolecular approach is still a big challenge.In this work,we report the noncovalent synthesis of TSCT TADF materials using a cyclic peptide-based bottle-brushed supramolecular polymer as a scaffold.By bringing the TSCT donor and acceptor in close proximity in space using the supramolecular scaffold,distinctive TADF emission in both solution and solid states could be achieved.Furthermore,the TADF system could be utilized as a sensitizer to coassemble with fluorescence acceptors to build thermally assisted fluorescence systems,resulting in color-tunable delayed fluorescence with high efficiency and color purity.Our findings provide a facile yet effective approach to designing and fabricating TSCT TADF materials,which might hold great potential for applications in the fields of organic light-emitting diode,bioimaging,and sensing. 展开更多
关键词 supramolecular chemistry cyclic peptide thermally activated delayed fluorescence throughspace charge transfer thermally assisted fluorescence
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One-shot synthesis of heavy-atom-modified carbazole-fused multi-resonance thermally activated delayed fluorescence materials
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作者 Jia-Jun Hu Jia-Qi Liang +3 位作者 Zhi-Ping Yan Hua-Xiu Ni Xiang-Ji Liao You-Xuan Zheng 《Science China Materials》 SCIE EI CAS CSCD 2024年第9期2789-2795,共7页
Efficient multi-resonance thermally activated delayed fluorescence(MR-TADF)materials hold significant potential for applications in organic light-emitting diodes(OLEDs)and ultra-high-definition displays.However,the st... Efficient multi-resonance thermally activated delayed fluorescence(MR-TADF)materials hold significant potential for applications in organic light-emitting diodes(OLEDs)and ultra-high-definition displays.However,the stringent synthesis conditions and low yields typically associated with these materials pose substantial challenges for their practical applications.In this study,we introduce an innovative strategy that involves peripheral modification with sulfur and selenium atoms for two materials,CFDBNS and CFDBNSe.This approach enables a directed one-shot borylation process,achieving synthesis yields of 66%and 25%,respectively,while also enhancing reverse intersystem crossing rates.Both emitters exhibit ultra-narrowband sky-blue emissions centered around 474 nm,with full width at half maximum(FWHM)values as narrow as 19 nm in dilute toluene solutions,along with high photoluminescence quantum yields of 98%and 99%in doped films,respectively.The OLEDs based on CFDBNS and CFDBNSe display sky-blue emissions with peaks at 476 and 477 nm and exceptionally slender FWHM values of 23 nm.Furthermore,the devices demonstrate remarkable performances,achieving maximum external quantum efficiencies of 24.1%and 27.2%.This work presents a novel and straightforward approach for the incorporation of heavy atoms,facilitating the rapid construction of efficient MR-TADF materials for OLEDs. 展开更多
关键词 one-shot synthesis multi-resonance thermally activated delayed fluorescence carbazole-fused dual-boron embedded framework ultra-narrowband emission organic light-emitting diode
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Chiral thermally activated delayed fluorescence materials for circularly polarized organic light-emitting diodes
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作者 Li Yuan Yi-Pin Zhang You-Xuan Zheng 《Science China Chemistry》 SCIE EI CAS CSCD 2024年第4期1097-1116,共20页
Chirality is an important natural characteristic of organic molecules,and chiral organic molecules have shown extensive application in areas such as pharmaceutical development and material science.Benefiting from the ... Chirality is an important natural characteristic of organic molecules,and chiral organic molecules have shown extensive application in areas such as pharmaceutical development and material science.Benefiting from the ability to achieve circularly polarized luminescence(CPL),chiral luminescent materials have shown potential applications in anti-glare display,optical communication and,3D display,etc.Due to the ability to harvest both singlet and triplet excitons by a fast reverse intersystem crossing process without involving noble metals,chiral thermally activated delayed fluorescence(TADF)materials with point chirality,axial chirality,planar chirality and helical chirality are regarded as the state-of-the-art materials for circularly polarized organic light-emitting diodes(CP-OLEDs).In recent years,the chiral TADF materials and CP-OLEDs have rapidly developed,but unfortunately,the dissymmetry factors(g)are far from the requirement of practical applications.The ideal emitters and devices should have both high efficiency and a g factor,or at least a balance between these two elements.This review gives an overview of recent progress in chiral TADF materials,with a particular focus on the chiral skeleton,CPL property and device performance.Furthermore,the molecular design concept,device structure and methods to improve the g factors of chiral materials and CP-OLEDs are also discussed. 展开更多
关键词 chiral thermally activated delayed fluorescence material chiral skeleton circularly polarized luminescence circularly polarized organic light-emitting diodes dissymmetry factor
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Chiral multiple-resonance thermally activated delayed fluorescence materials based on chiral spiro-axis skeleton for efficient circularly polarized electroluminescence
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作者 Shi-Quan Song Xiao Han +4 位作者 Zhong-Zhong Huo Ching-Fai Yip Xian-Fang Hong Meng-Ning Ding You-Xuan Zheng 《Science China Chemistry》 SCIE EI CAS CSCD 2024年第7期2257-2264,共8页
Chiral luminescence materials have potential applications in the field of three-dimensional displays due to their circularly polarized luminescence(CPL)characteristics.However,the further development of circularly pol... Chiral luminescence materials have potential applications in the field of three-dimensional displays due to their circularly polarized luminescence(CPL)characteristics.However,the further development of circularly polarized organic light-emitting diodes(CP-OLEDs)needs to meet the requirements of high efficiency,high color purity,low cost,and high dissymmetry factor(gPLor gEL),chiral multiple resonance thermally activated delayed fluorescence(MR-TADF)materials are considered as candidates in these aspects.Herein,based on a pair of chiral spirofluorene precursors,two pairs of high-performance chiral MR-TADF emitters((R/S)-p-Spiro-DtBuCzB and(R/S)-m-Spiro-DtBuCzB)are developed,which exhibit strong emissions peaking at 491 and 502 nm in toluene with full-width at half-maximum values of 25 and 33 nm,respectively.In addition,small singlet–triplet energy gaps of 0.15 and 0.10 eV with high absolute photoluminescence efficiencies of 95.0%and 96.7%are observed for p-Spiro-DtBuCzB and m-Spiro-DtBuCzB molecules,respectively.OLEDs based on p-Spiro-DtBuCzB and m-Spiro-DtBuCzB display high maximum external quantum efficiencies of 29.6%and 33.8%,respectively.Most importantly,CP-OLEDs present symmetric circularly polarized electroluminescence spectra with|gEL|factors of 3.36×10^(-4)and 7.66×10^(-4)for devices based on(R/S)-p-Spiro-DtBuCzB and(R/S)-m-Spiro-DtBuCzB enantiomers,respectively. 展开更多
关键词 chiral spiro-axis skeleton-based material multiple resonance thermally activated delayed fluorescence circularly polarized electroluminescence dissymmetry factor external quantum efficiency
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TADF敏化荧光策略构建高效、窄光谱发光电化学池器件
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作者 陈荔丝 蓝燕婷 +5 位作者 赵小龙 秦冬冬 张玉微 陶春兰 张保华 牛利 《发光学报》 EI CAS CSCD 北大核心 2024年第4期651-661,共11页
基于新一代热活化延迟荧光(Thermally activated delayed fluorescence,TADF)发光材料的发光电化学池(Light-emitting electrochemical cells,LECs)成为新兴的研究方向而受到关注。由于TADF发光材料电荷分离态的激子属性,该类LECs器件... 基于新一代热活化延迟荧光(Thermally activated delayed fluorescence,TADF)发光材料的发光电化学池(Light-emitting electrochemical cells,LECs)成为新兴的研究方向而受到关注。由于TADF发光材料电荷分离态的激子属性,该类LECs器件发光光谱半峰宽往往达到100 nm以上,难以满足LEC高色纯度的需求。鉴于此,本文尝试将TADF敏化荧光(TADF-sensitized fluorescence,TSF)的激子管控策略应用到LECs领域当中。通过筛选合适的传输主体、TADF敏化剂、高吸光系数荧光染料和离子液体固态电解质为LEC的发光层,我们成功构建了高效TSF型的LECs器件。最终获得的TSF-LECs器件峰值外量子效率(The highest external quantum ef-ficiency,EQEmax)达到3.7%,峰值亮度(The peak luminance,Lmax)达到2285 cd·m^(-2)。与TADF-LECs的参比器件相比,TSF-LECs器件的光谱半峰宽(Full width at half maximum,FWHM)从106 nm降低至38 nm。本文还详细讨论了所制备TSF-LECs器件中的能量转移和激子损失途径。该工作为进一步优化设计TSF-LECs材料和器件奠定了基础。 展开更多
关键词 发光电化学池 tadf敏化荧光 BODIPYs 热活化延迟荧光
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Bipolar Thermally Activated Delayed Fluorescence Emitter with Balanced Carrier Transport for High-Efficiency Nondoped Green Electroluminescent Devices
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作者 Yuchao Liu Zhagen Miao +5 位作者 Haikuo Gao Shian Ying Can Gao Shouke Yan Huanli Dong Zhongjie Ren 《CCS Chemistry》 2024年第9期2346-2357,共12页
High-efficiency electroluminescent devices featuring simplified architecture have received considerable attention due to significant advantages in construction procedures and commercialized applications.However,there ... High-efficiency electroluminescent devices featuring simplified architecture have received considerable attention due to significant advantages in construction procedures and commercialized applications.However,there still remains a critical challenge with regard to the lack of organic semiconductors that simultaneously possess high luminescent efficiency and balanced carrier-transporting abilities.Herein,we design a thermally activated delayed fluorescence(TADF)emitter 4-(9,9-dimethyl-9,10-dihydroacridine)-4′-triphenylphosphineoxide-benzophenone(DMAC-BPTPO)by incorporating triphenylphosphine oxide into the donor–acceptor skeleton.The accessional electrontransporting moiety,rod-like dimer,and horizontally packing model synergistically enable DMAC-BP-TPO which possesses an excellent photoluminescence quantum yield of nearly 90%with a reverse intersystem crossing rate constant of 2.0×106 s−1,horizontal dipole ratio of 89%,and a balanced electron and hole mobilities with a small constrast ratio of 1.08.Eventually,simplified electroluminescent devices including organic lightemitting diodes(OLEDs)and organic light-emitting transistors(OLETs)incorporating DMAC-BP-TPO-based nondoped film are demonstrated due to their superior integrated optoelectronic properties along with preferable horizontal dipole orientation.A record-high external quantum efficiency value of 21.7%and 4.4%are finally achieved in the simplified nondoped OLED and OLET devices,which are among the highest values in the related research fields.This work provides a new avenue to develop a high-efficiency bipolar TADF emitter to advance the simplified electroluminescent devices. 展开更多
关键词 organic light-emitting diode organic lightemitting transistor bipolar thermally activated delayed fluorescence nondoped active layer
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Thermally activated delayed fluorescence materials for nondoped organic light-emitting diodes with nearly 100%exciton harvest 被引量:3
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作者 Xiao-Chun Fan Kai Wang +7 位作者 Yi-Zhong Shi Dian-Ming Sun Jia-Xiong Chen Feng Huang Hui Wang Jia Yu Chun-Sing Lee Xiao-Hong Zhang 《SmartMat》 2023年第1期129-139,共11页
High-performance nondoped organic light-emitting diodes(OLEDs)are promising technologies for future commercial applications.Herein,we synthesized two new thermally activated delayed fluorescence(TADF)emitters that ena... High-performance nondoped organic light-emitting diodes(OLEDs)are promising technologies for future commercial applications.Herein,we synthesized two new thermally activated delayed fluorescence(TADF)emitters that enable us,for the first time,to combine three effective approaches for enhancing the efficiency of nondoped OLEDs.First,the two emitters are designed to have high steric hindrances such that their emitting cores will be suitably isolated from those of their neighbors to minimize concentration quenching.On the other hand,each of the two emitters has two stable conformations in solid films.In their neat films,molecules with the minority conformation behave effectively as dopants in the matrix composing of the majority conformation.One hundred percent exciton harvesting is thus theoretically feasible in this unique architecture of“self-doped”neat films.Furthermore,both emitters have relatively high aspect ratios in terms of their molecular shapes.This leads to films with preferred molecular orientations enabling high populations of horizontal dipoles beneficial for optical outcoupling.With these three factors,OLEDs with nondoped emitting layers of the respective emitters both achieve nearly 100%exciton utilization and deliver over 30%external quantum efficiencies and ultralow efficiency roll-off at high brightness,which have not been observed in reported nondoped OLEDs. 展开更多
关键词 dual conformations horizontal orientation organic light-emitting diodes SELF-DOPING thermally activated delayed fluorescence
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Realizing External Quantum Efficiency over 25% with Low Efficiency Roll-Off in Polymer-Based Light-Emitting Diodes Synergistically Utilizing Intramolecular Sensitization and Bipolar Thermally Activated Delayed Fluorescence Monomer 被引量:2
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作者 Yuchao Liu Yanchao Xie +4 位作者 Lei Hua Xingwen Tong Shian Ying Zhongjie Ren Shouke Yan 《CCS Chemistry》 CSCD 2023年第4期1005-1017,共13页
Since polymer-based light-emitting diodes(PLEDs)arewellsuited building blocks for large-area and low-cost flexible display equipment,state-of-the-art thermally activated delayed fluorescence(TADF)PLEDs are in high dem... Since polymer-based light-emitting diodes(PLEDs)arewellsuited building blocks for large-area and low-cost flexible display equipment,state-of-the-art thermally activated delayed fluorescence(TADF)PLEDs are in high demand.To respond to this demand,light-emitting TADF units have initially been modified with electron-transporting units to balance the carrier transport of regiorandom TADF polymers,and simultaneously,an intramolecular sensitizing strategy has also been employed by covalently incorporating TADF sensitizers with light-emitting TADF units and hosts in conjugated polymers to accelerate the spin-flip of triplet excitons.Superior photophysical properties have been achieved by a rational regulation of the proportions of each component,achieving a photoluminescence quantumyield of 90%,an extremely high rate of reverse intersystem crossing of 3×106 s−1,and a relatively low nonradiative decay rate of around 105 s−1.As a result,the solutionprocessed PLEDs can attain an external quantum efficiency(EQE)value of 25.4%with emission peaks of around 550 nm,representing record-high performance for PLEDs.The efficiency roll-off can also be significantly suppressed,maintaining an EQE value of 24.2%at 1000 cd/m2 with ideal efficiency roll-off of lower than 5%.Encouragingly,this work provides a valid strategy to tackle the imperative need for PLEDs with high EQE and low efficiency roll-off. 展开更多
关键词 thermally activated delayed fluorescence polymer light-emitting diodes intramolecular sensitizing strategy balanced carrier transports low efficiency roll-off
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Phosphonium-Based Ionic Thermally Activated Delayed Fluorescence Emitters for High-Performance Partially Solution-Processed Organic Light-Emitting Diodes 被引量:2
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作者 Xu-Lin Chen Xiao-Dong Tao +5 位作者 Ya-Shu Wang Zhuangzhuang Wei Lingyi Meng Dong-Hai Zhang Fu-Lin Lin Can-Zhong Lu 《CCS Chemistry》 CAS CSCD 2023年第3期589-597,共9页
Ionic thermally activated delayed fluorescence(TADF)emitters are rarely investigated due to their poor photoluminescence and electroluminescence performance.Herein,highly efficient ionic TADF emitters with charged do... Ionic thermally activated delayed fluorescence(TADF)emitters are rarely investigated due to their poor photoluminescence and electroluminescence performance.Herein,highly efficient ionic TADF emitters with charged donor–acceptor(D–A^(+))and D–A^(+)–D architectures are designed,innovatively based on the phosphonium cation electron acceptor.The symmetric D–A^(+)–D compound in doped film exhibits a high photoluminescence quantum yield of 0.91 and a short emission lifetime of 1.43 microseconds.Partially solution-processed organic lightemitting diodes based on these ionic TADF emitters achieve a maximum external quantum efficiency(EQE)of 18.3%and a peak luminance of 14,532 candelas per square meter(cd/m^(2))and show a small efficiency roll-off of 7.1%(EQE=17%)at a practical high luminance of 1000 cd/m^(2).These results demonstrate the high potential of phosphonium cations as promising electron acceptors to construct TADF emitters for high-performance electroluminescence devices.The current study opens up an appealing way for future exploitation of high-efficiency ionic TADF materials. 展开更多
关键词 cation acceptor charge transfer PHOSPHONIUM ionic emitter thermally activated delayed fluorescence partially solution-processed host-guest organic light-emitting diode efficiency roll-off
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Perspective for aggregation-induced delayed fluorescence mechanism:A QM/MM study
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作者 Jie Liu Jianzhong Fan +3 位作者 Kai Zhang Yuchen Zhang Chuan-Kui Wang Lili Lin 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第8期531-537,共7页
To enhance the potential application of thermally activated delayed fluorescence(TADF)molecular materials,new functions are gradually cooperated to the TADF molecules.Aggregation induced emission can effectively solve... To enhance the potential application of thermally activated delayed fluorescence(TADF)molecular materials,new functions are gradually cooperated to the TADF molecules.Aggregation induced emission can effectively solve the fluorescence quenching problem for TADF molecules in solid phase,thus aggregation-induced delayed fluorescence(AIDF)molecules were recently focused.Nevertheless,their luminescent mechanisms are not clear enough.In this work,excited state properties of an AIDF molecule DMF-BP-DMAC[reported in Chemistry-An Asian Journal 14828(2019)]are theoretically studied in tetrahydrofuran(THF)and solid phase.For consideration of surrounding environment,the polarizable continuum method(PCM)and the combined quantum mechanics and molecular mechanics(QM/MM)method were applied for solvent and solid phase,respectively.Due to the increase of the transition dipole moment and decrease of the energy difference between the first single excited state(S1)and the ground state(S0),the radiative rate is increased by about 2 orders of magnitude in solid phase.The energy dissipation of the non-radiative process from S1 to S0 is mainly contributed by low-frequency vibrational modes in solvent,and they can be effectively suppressed in aggregation,which may lead to a slow non-radiation process in solid phase.Both factors would induce enhanced luminescence efficiency of DMF-BP-DMAC in solid phase.Meanwhile,the small energy gap between S1 and triplet excited states results in high reverse intersystem crossing(RISC)rates in both solvent and solid phase.Therefore,TADF is confirmed in both phases.Aggregation significantly influences both the ISC and RISC processes and more RISC channels are involved in solid state.The enhanced delayed fluorescence should be induced by both the enhanced fluorescent efficiency and ISC efficiency.Our calculation provides a reasonable explanation for experimental measurements and helps one to better understand the luminescence mechanism of AIDF molecules. 展开更多
关键词 thermally activated delayed fluorescence aggregation-induced delayed fluorescence the combined quantum mechanics and molecular mechanics method
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Fine Tuning of Donor-Acceptor Structures in Fused-Carbazole Containing Thermally Activated Delayed Fluorescence Materials towards High-Efficiency OLEDs
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作者 Wenbo Yuan Weiyang Hu +4 位作者 Jian Wang Mengyuan Zhu Changsheng Shi Ning Sun Youtian Tao 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2023年第15期1829-1835,共7页
Comprehensive Summary Conjugated fused-ring structures have attracted extensive attention due to their high molecular rigidity to restrain excited-state relaxation and non-radiative decay,and further to enhance the lu... Comprehensive Summary Conjugated fused-ring structures have attracted extensive attention due to their high molecular rigidity to restrain excited-state relaxation and non-radiative decay,and further to enhance the luminance efficiency for emissive materials.Herein,we develop a series of donor-acceptor type thermally activated delayed fluorescence(TADF)emitters by introducing fused-ring 5H-benzofuro[3,2-c]carbazole(32BFCz)as electron donating unit.Through optimizing the numbers and structure of donor and acceptor moieties,three compounds named 32BFCzA,mCF3BFCzOXD and dCF3BFCzOXD are designed,which are composed by mono-32BFCz/trifluoromethylpicolinonitrile,penta-BFCz/3-(trifluoromethyl)phenyl)-1,3,4-oxadiazol-2-yl)benzene and penta-32BFCz/3,5-bis(trifluoromethyl)phenyl)-1,3,4-oxadiazol-2-yl)benzene as donor/acceptor groups,respectively. 展开更多
关键词 DONOR-ACCEPTOR Dipole moment thermally activated delayed fluorescence Organic light-emitting diodes External quantum efficiency
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