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blue emission from Exciplex in Electroluminescent Devices Made from Vinyl Polymer and Oxadiazole Derivative

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Journal of Shanghai University(English Edition) 2005年第3期9卷 275-278页

作者：朱文清蒋雪茵张志林 School of Materials Science and Engineering Shanghai University Shanghai 201800 P.R. China

Two types of molecular and polymer devices employing (2-(4′-biphenyl)-5-(4″-tert-butylphenyl)-1,3,4-oxadiazole) (PBD) and poly(N-vinylcarbazole)(PVK) as electron transport and hole transport materials, respectively, have been fabricated. The structures of these two devices are ITO/PVK(70 nm)/PBD(60 nm)/Al and ITO/PVK∶PBD(1∶1 by mass, 70 nm)/Al. The formation of exciplex is evident by comparing the electroluminescence (EL) of a bi-layer device and the photoluminescence (PL) of a PVK and PBD mixed film. The maximum emission energy of exciplex evaluated is consistent with the peak emission of EL. blue emissions from both devices are obtained. The type of exicplex is interpreted based on the energy level diagram of the bi-layer device.

关键词： organic electroluminescence exciplex blue emission color tuning.

Cs-based Quasi-2D Perovskite: Toward Efficient Perovskite Light-Emitting Diodes with blue emission

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Cs-based Quasi-2D Perovskite: Toward Efficient Perovskite Li...

Developments and challenges ahead in blue perovskite light-emitting devices

第六届新型太阳能电池材料科学与技术学术研讨会

作者：黎振超陈梓铭叶轩立 State Key Laboratory of Luminescent Materials and Devices School of Materials Science and EngineeringSouth China University of Technology

In recent years, metal halide perovskites have shown promising potential in a series of optoelectronic applications such as solar cells, light-emitting diodes(LEDs), photodetectors and lasers. However, blue perovskite LEDs currently still suffer from inferior performance. Therefore, a breakthrough in thin-film perovskite LEDs with blue emission is an urgent target in this field. In our recent work, we push up the efficiency of blue perovskite LEDs combining three key strategies: composition engineering, dimensional engineering and modulation of recombination zone position. Firstly, through composition and dimensional engineering, we prepare quasi-two-dimensional perovskite thin films with improved blue emission, taking advantages of reduced trap density and enhanced photoluminescence properties. Secondly, we find a vertically non-uniform distribution of perovskite crystals in the PEDOT:PSS/perovskite hybrid film. Through modulating the position of the recombination zone, we activate the majority of quasi-two-dimensional perovskite crystals, and thus demonstrate highly efficient blue perovskite light-emitting diode with emission peak at 480 nm, luminance of 3780 cd m and external quantum efficiency of 5.7%.

关键词： Perovskite Light-emitting diode blue emission

来源： cnki会议评论

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Journal of Energy Chemistry 2022年第8期31卷 418-433,I0011页

作者： Lin Zhang Run Long College of Chemistry Key Laboratory of Theoretical&Computational Photochemistry of Ministry of EducationBeijing Normal UniversityBeijing 100875China

Recently,perovskite light-emitting diodes(Pe LEDs)have developed rapidly in the green,red,and nearinfrared light emissions,owing to the unique optoelectronic characteristics of halide perovskites,such as high carrier mobility,narrow emission linewidths,high photoluminescence quantum yield,as well as bandgap ***,the efficiency improvement in blue(especially deep-blue)Pe LEDs is still inferior to other analogs,which severely restricts the Pe LED ***,we systematically summarize the substantial progress in the performance of blue Pe LEDs based on different blue perovskite candidates,and recent advances from three aspects(i.e.,the sky-blue,pure-blue,and deep-blue light emissions).Then,we point out several challenges existing in deep-blue Pe LEDs,such as the effect of Cl-ions incorporation,spectral instability,ion migration,and the difficulty of charge injection,and highlight the strategies to improve device efficiency,to motivate further research and development of blue Pe LEDs.

关键词： Perovskite blue emission Light-emitting diodes Stability Efficiency

Fine-tuning the thicknesses of organic layers to realize high-efficiency and long-lifetime blue organic light-emitting diodes

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Chinese Physics B 2012年第8期21卷 186-190页

作者：于建宁张民艳李崇尚玉柱吕燕芳魏斌黄维 Key Laboratory of Advanced Display and System Applications Ministry of EducationShanghai University Key Laboratory for Organic Electronics&Information Displays and Institute of Advanced Material Nanjing University of Posts and Telecommunications

By using p-bis（p - N, N-diphenyl-aminostyryl）benzene doped 2-tert-butyl-9, 10-bis-β-naphthyl）-anthracene as an emitting layer, we fabricate a high-efficiency and long-lifetime blue organic light emitting diode with a maximum external quantum efficiency of 6.19% and a stable lifetime at a high initial current density of 0.0375 A/cm2. We demonstrate that the change in the thicknesses of organic layers affects the operating voltage and luminous efficiency greater than the lifetime. The lifetime being independent of thickness is beneficial in achieving high-quality full-colour display devices and white lighting sources with multi-emitters.

关键词： organic light-emitting diode blue emission lifetime organic layers thickness

Non-conjugated Polynorbornene Hosts with High Triplet Energy Levels for Solution-processed Narrowband blue OLEDs

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Chemical Research in Chinese Universities 2023年第5期39卷 763-771页

作者： LI Qiang CHEN Liang WANG Xingdong WANG Shumeng SHAO Shiyang WANG Lixiang State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022P.R.China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026P.R.China State Key Laboratory of Marine Resource Utilization in South China Sea School of Materials Science and EngineeringHainan UniversityHaikou 570228P.R.China

Three polymer hosts(namely PNB-tBuCz,PNB-Ac,PNB-TAc)containing non-conjugated polynorbornene(PNB)backbone and hole-transporting arylamine segments(carbazole,acridan and dendritic teracridan)in side chains are developed for solution-processed narrowband blue organic light-emitting diodes(OLEDs).It is found that the non-conjugated polynorbornenes can keep high triplet energy(ET)levels in range of 3.12-3.20 eV by interrupting the conjugation of repeating units,making them capable as host materials for blue ***,by increasing the electron-donating capability of side chain arylamine from carbazole to acridan and dendritic teracridan,the highest occupied molecular orbital(HOMO)levels for the polymer hosts are elevated from-5.50 eV to-5.11 eV,beneficial for reducing the hole injection barrier from anode to emissive *** a result,solution-processed OLEDs employing polynorbornenes with dendritic teracridan side chain(PNB-TAc)as host and boron,selenium,nitrogen-containing multiple resonance thermally activated delayed fluorescence emitter as dopant reveal efficient narrowband blue electroluminescence with emission peak at 474 nm,full-width at half maximum of 30 nm,together with maximum external quantum efficiency of 20.2%,representing the state-of-the-art device efficiency for solution-processed OLEDs with narrowband blue emission.

关键词： Polymer host Polynorbornene Organic light-emitting diode Solution-processed Narrowband blue emission

A Tetranuclear Cuprous Halide Cluster Exhibiting Efficient blue Thermally Activated Delayed Fluorescence

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Chinese Journal of Structural Chemistry 2021年第11期40卷 1489-1495,1408页

作者： WANG Pei HUANG Chun-Hua CHEN Xu-Lin LU Can-Zhong CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China Xiamen Institute of Rare-earth Materials Haixi InstitutesChinese Academy of SciencesXiamen 361021China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China Huaqiao University Xiamen 361021China University of Chinese Academy of Sciences Beijing 100049China

A new tetranuclear cuprous halide complex,(CuBr)_(4)(PN)_(2)(PN=2-(diphenylphosphaneyl)-6-methoxypyridine),was synthesized and fully *** solid state,this complex exhibits efficient blue emission with a photoluminescence quantum yield of 43.3%and a decay time of 19μs at room *** theoretical calculations,combined with the temperature dependence of spectroscopic properties and emission decay behaviors,indicate that the emission in the solid state originates from the ^(1,3)(MLCT+XLCT)excited states,which are in thermal equilibrium with a small energy gap of about 0.1 eV.

关键词： cuprous complex thermally activated delayed fluorescence blue emission photoluminescence

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Bipolar blue Light-emitting Polyfluorenes Containing Dibenzothiophene-S,S-dioxide/Carbazole Units

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Chemical Research in Chinese Universities 2018年第3期34卷 506-512页

作者： LIANG Li LIU Jie ZHANG Yuhao HU Liwen GUO Ting YANG Wei CAO Yong Institute of Polymer Optoeleetronie Materials and Devices State Key Laboratory of Luminescent Materials and DevicesSouth China University of Technology Guangzhou 510640 P. R. China

Bipolar blue light-emitting polyfluorenes（PFSO-Cz） containing electron-deficient dibenzothiophene-S,S- dioxide（SO） and electron-rich carbazole（Cz） unit were synthesized. All the polymers show a high thermal stability with the decomposition temperatures over 400 ℃ and higher photoluminescence quantum yields. The highest occupied molecular orbital energy levels（EHMH＇s） slightly enhance and the lowest unoccupied molecular orbital energy levels（ELuMo＇S） gently depress with the increase of Cz content in the polymers. PL spectra of the polymers display remarkable red shift and broadening with the increase of solvent polarities, indicating significant intramolecular charge transfer（ICT） effect in the polymers. Electroluminescence（EL） spectra of the polymers exhibit a broadening tendency with increasing the content of Cz unit in the polymers. The superior device performances were obtained with the maximum lumhlous efficiency（LEmax） of 5.2 cd/A, the maximum external quantum efficiency（EQEmax） of 4.8% and the Internationale de I＇Eclairage（CIE）（x,y） coordinates of （0.16, 0.17） for PFSO15-Cz10 based on the single-layer device of ITO/PEDOT：PSS/EL/CsF/A1. The results indicate that the efficient bipolar blue light-emitting polyfluorenes are also constructed by Suzuki copolymerization using the monomers in common use.

关键词： Dibenzothiophene-S S-dioxide Carbazole Polyfluorene blue emission Polymer light-emitting diode

Recent advances and prospects toward blue perovskite materials and light-emitting diodes

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InfoMat 2019年第2期1卷 211-233页

作者： Tao Fang Fengjuan Zhang Shichen Yuan Haibo Zeng Jizhong Song School of Materials Science and Engineering Nanjing University of Science and TechnologyNanjingChina MIIT Key Laboratory of Advanced Display Materials and Devices Institute of Optoelectronics and NanomaterialsNanjingChina

Perovskite based light-emitting diodes(PeLEDs)have become a powerful candidate for next-generation solid-state lightings and high-definition displays due to their high photoluminescence quantum yield(PLQY),tunable emission wavelength over the visible spectrum,and narrow emission *** the past few years,the development of red-and green-emissive PeLEDs has rapidly increased,and the corresponding external quantum efficiencies(EQE)have exceeded 20%.However,the research progress of blue-emitting PeLEDs is limited by its poor material quality and inappropriate device ***,the maximum EQE of blue PeLED is only 6.2%,which is far from the industrialization *** order to promote the development of blue PeLEDs,we summarize the recent research progress of blue perovskite materials and LEDs and discuss several fatal challenges,mainly embodied in low efficiency and poor *** order to overcome these challenges,detailed analysis and strategies are put forward in terms of the materials and *** the former,we summarize the feasible strategy for the preparation of efficient and stable blue-emissive perovskites using component *** the latter,we analyze the advantages and limitations of the different strategies for blue-emissive perovskite in *** the end of the review,a comprehensive outlook is detailed,including future development directions and several technical problems to be ***,we aim to highlight the significance and promote the industrialization of PeLEDs.

关键词： blue emission component engineering efficiency light-emitting diodes perovskites stability

Highly Efficient blue Organic Light-Emitting Diode Based on a Pyrene[4,5-d]Imidazole-Pyrene Molecule

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CCS Chemistry 2022年第1期4卷 214-227页

作者： Yulong Liu Xiaxia Man Qing Bai Hui Liu Pengyuan Liu Ying Fu Dehua Hu Ping Lu Yuguang Ma State Key Laboratory of Supramolecular Structure and Materials Department of ChemistryJilin UniversityChangchun 130012 Department of Chemistry College of Arts and SciencesNortheast Agricultural UniversityHarbin 150030 The First Hospital of Jilin University Changchun 130021 Institute of Polymer Optoelectronic Materials and Devices State Key Laboratory of Luminescent Materials and DevicesSouth China University of TechnologyGuangzhou 510640

Organic light-emitting diodes(OLEDs),which have been recently utilized in some flat-panel display screens such as mobile phones and televisions,show many merits,including light weight,high flexibility,energy preservation,and so forth,and are considered the next-generation displays and solid-state ***-emitting materials that can be applied in nondoped OLEDs with little efficiency roll-offs at high brightness are of great ***,a highly efficient,blue-emitting material,9-phenyl10-(4-(pyren-1-yl)phenyl)-9H-pyreno[4,5-d]imidazole(PyPI-Py),is achieved using pyrene[4,5-d]imidazole and pyrene as the weak electron donor and electron acceptor,*** nondoped blue OLED exhibits excellent performance with a maximum brightness of 75,687 cd m^(−2),a maximum current efficiency of 13.38 cd A−1,and a maximum external quantum efficiency(ηext)of 8.52%.Moreover,theηext is maintained at 8.35%and 8.05%at a brightness of 10,000 and 50,000 cd m^(−2),respectively,displaying extremely small efficiency roll-offs of 2.0%and 5.5%.The device characteristics are among the highest values for nondoped blue OLEDs and correspond to the best performance obtained for nondoped pyrene-based blue *** superior performance is attributed to the proper donor–acceptor design strategy which results in a quasi-equivalent hybrid local and charge-transfer excited state with the maximum generation of an 82%fraction of singlet excitons.

关键词： pyrene imidazole nondoped OLEDs blue emission efficiency roll-off