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Chinese Physics B 2010年第3期19卷 450-455页

作者：魏斌廖英杰刘纪忠路林曹进王军张建华 key Laboratory of advanced display and system applications Ministry of Education Shanghai University

This paper utilizes multilayer organic light-emitting diodes with a thin layer of dye molecules to study the mech- anism of charge trapping under different electric regimes. It demonstrates that the carrier trapping was independent of the current density in devices using fluorescent material as the emitting molecule while this process was exactly opposite when phosphorescent material was used. The triplet-triplet annihilation and dissociation of excitons into free charge carriers was considered to contribute to the decrease in phosphorescent emission under high electric fields. Moreover, the fluorescent dye molecule with a lower energy gap and ionized potential than the host emitter was observed to facilitate the carrier trapping mechanism, and it would produce photon emission.

关键词： organic light-emitting diodes excitation mechanism charge trapping current density

Estimation of electron mobility of n-doped 4,7-diphenyl-1,10-phenanthroline using space-charge-limited currents

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Journal of Semiconductors 2009年第11期30卷 63-66页

作者：希扎尔.乌尔.哈克鲁富翰蒋雪茵张志林张小文张良李俊 School of Materials Science and Engineering Shanghai University key laboratories of advanced display and system applications Ministry of EducationShanghai University

The electron mobilities of 4, 7-diphenyl-1, 10-phenanthroline （BPhen） doped 8-hydroxyquinolinatolithium （Liq） at various thicknesses （50-300 nm） have been estimated by using space-charge-limited current measurements. It is observed that the electron mobility of 33 wt% Liq doped BPhen approaches its true value when the thickness is more than 200 rim. The electron mobility of 33 wt% Liq doped BPhen at 300 nm is found to be -5.2 × 10^-3 cm^2/（V.s）（at 0.3 MV/cm） with weak dependence on electric field, which is about one order of magnitude higher than that of pristine BPhen （3.4 × 10^-4 cm^2/（V.s）） measured by SCLC. For the typical thickness of organic light-emitting devices, the electron mobility of doped BPhen is also investigated.

关键词： doping electron mobility SCLC 8-hydroxyquinolinonate-lithium (Liq)

Efficiency enhancement in DIBSQ：PC71BM organic photovoltaic cells by using Liq-doped Bphen as a cathode buffer layer

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Frontiers of Materials Science 2017年第3期11卷 233-240页

作者： Guo CHEN Changfeng SI Pengpeng ZHANG Kunping GUO Saihu PAN Wenqing ZHU Bin WEI key Laboratory of advanced display and system applications (Ministry of Education) Shanghai University Shanghai 200072 China

We have improved the photovoltaic performance of 2,4-bis[4-（N,N- diisobutylamino）-2,6-dihydroxyphenyl] squaraine：[6,6]-phenyl C71-butyric acid methyl ester （DIBSQ：PC71BM） organic photovoltaic （OPV） cells via incorporating Liq-doped Bphen （Bphen-Liq） as a cathode buffer layer （CBL）. Based on the Bphen-Liq CBL, a DIBSQ：PC71BM OPV cell possessed an optimal power conversion efficiency of 4.90%, which was 13% and 60% higher than those of the devices with neat Bphen as CBL and without CBL, respectively. The enhancement of the device performance could be attributed to the enhanced electron mobility and improved electrode/active layer contact and thus the improved photocurrent extraction by incorporating the Bphen-Liq CBL. Light-intensity dependent device performance analysis indicates that the incorporating of the Bphen-Liq CBL can remarkably improve the charge transport of the DIBSQ：PC71BM OPV cell and thus decrease the recombination losses of the device, resulting in enhanced device performance. Our finding indicates that the doped Bphen-Liq CBL has great potential for high-performance solution-processed small-molecule OPVs.

关键词： organic photovoltaic cells squaraine cathode buffer layer power conversion efficiency solution-process

A novel solution-based self-assembly approach to preparing ultralong titanyl phthalocyanine sub-micron wires

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Chinese Physics B 2014年第7期23卷 655-660页

作者：朱宗鹏魏斌张建华王军 School of Materials Science and Engineering Shanghai University key Laboratory of advanced display and system applications Ministry of EducationShanghai University

Ultralong titanyl phthalocyanine （TiOPc） sub-micron wires have been synthesized by a novel solution-based self- assembly method. By using different solvents, changing the mass concentration and the solvent vapor pressure, the length and the shape of the wires can be adjusted. The mixed-phase properties of the TiOPc sub-micron wires were investigated by the ultraviolet-visible （UV-vis） absorption spectrum and X-ray diffraction. Organic transistors based on these wires were studied, which show the typical p-channel characteristics.

关键词： titanyl phthalocyanine sub-micron wire transistor solution method

Influence of reaction parameters on the luminescence properties of monodisperse NaGd（1-x-y）（WO4）2:xEu3+,yTb3+ phosphor by molten salt synthesis

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Journal of Rare Earths 2018年第1期36卷 49-57页

作者： Weiqin Xiao Luqiao Yin Jipeng Zhou Fang Lei Ying Shi Jianjun Xie Lei Zhang School of Materials Science and Engineering Shanghai University key Laboratory of advanced display and system applications Ministry of Education (Shanghai University)

Eu3+activated and Eu3+, Tb3+co-activated monodisperse sodium double tungstates NaGd（WO4）2 phosphors were prepared by molten salt method at 750 ℃ for 10 h using NaCl as a flux. The crystal structure and morphology of the as-synthesized phosphors were measured by XRD and SEM, respectively. The photoluminescence properties were characterized by PL spectra, decay lifetime and CIE. The presence of NaCl plays an important role in the morphology and luminescence properties. In this work,NaCl and one of the raw material Na2CO3in a certain proportion will form a low eutectic salt to decrease the reaction temperature and benefit the formation of monodisperse NaGd（WO4）2crystals. The color of Eu3+and Tb3+co-doped NaGd（WO4）2phosphors can be tuned from creamy white to orange, red and green by adjusting the doping concentration of rare earth ions, since the emission contain the broad blue-green emission origin from NaGd（WO4）2host and characteristic red and green emission origin from Eu3+and Tb3+ions. The electroluminescent spectra and CIE measurement shows that the LED device with NaGd（1-x）（WO4）2:xEu3+（x = 0.24） phosphor can be excited by 365 nm and 380 nm LED chip, and their CIE coordinate is（x = 0.45, y = 0.45） and（x = 0.36, y = 0.37）, Ra is 80.3 and 86.3, Tcis 3196 and4556 K, respectively. As a single-component phosphor, NaGd（WO4）2:Eu3+,Tb3+have potential application in UV-pumped WLEDs.

关键词： NaGd(1-x-y)(WO4)2:xEu3+ yTb3+ Molten salt method Single component WLEDs White light

Pure blue and white light electroluminescence in a multilayer organic light-emitting diode using a new blue emitter

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Chinese Physics B 2014年第7期23卷 727-731页

作者：魏娜郭坤平周朋超于建宁魏斌张建华 School of Materials Science and Engineering Shanghai University key Laboratory of advanced display and system applications of Ministry of Education Shanghai University

We characterized the 6,12-bis{[N-（3,4-dimethylphenyl）-N-（2,4,5-trimethylphenyl）]amino} chrysene （BmPAC）, which has been proven to be a blue fluorescent emission with high EL efficiency. The blue fluorescent device exhibits good performance with an external quantum efficiency of 5.8% and current efficiency of 8.9 cd/A, respectively. Using BmPAC, we also demonstrate a hybrid phosphorescence/fluorescence white organic light-emitting device （WOLED） with high efficiency of 36.3 cd/A. In order to improve the relative intensity of blue light, we plus a blue light-emitting layer （BEML） in front of the orange light emitting layer （YEML） to take advantage of the excess singlet excitons. With the new emitting layer of BEML/YEML/BEML, we demonstrate the fluorescence/phosphorescence/fluorescence WOLED exhibits good performance with a current efficiency of 47 cd/A and an enhanced relative intensity of blue light.

关键词： BmPAC high efficiency blue organic light emitting diodes white organic light-emitting diodes

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

Exciplex formation and electroluminescent absorption in ultraviolet organic light-emitting diodes

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Chinese Physics B 2015年第2期24卷 253-258页

作者：张琪张浩张小文徐韬魏斌 School of Materials Science and Engineering & key Laboratory of advanced display and system applications Ministry of EducationShanghai University Guangxi key Laboratory of Information Materials Guilin University of Electronic Technology

We investigated the formation of exciplex and electroluminescent absorption in ultraviolet organic light-emitting diodes（UV OLEDs） using different heterojunction *** is found that an energy barrier of over 0.3 eV between the emissive layer（EML） and adjacent transport layer facilitates exciplex *** electron blocking layer effectively confines electrons in the EML,which contributes to pure UV emission and enhances *** change in EML thickness generates tunable UV emission from 376 nm to 406 *** addition,the UV emission excites low-energy organic function layers and produces photoluminescent *** UV OLED,avoiding the exciplex formation and averting light absorption can effectively improve the purity and efficiency.A maximum external quantum efficiency of 1.2%with a UV emission peak of 376 nm is realized.

关键词： exciplex tunable UV emission electroluminescent absorption

InP quantum dots-based electroluminescent devices

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Chinese Physics B 2019年第11期28卷 18-24页

作者： Qianqian Wu Fan Cao Lingmei Kong Xuyong Yang School of Material Science and Engineering Shanghai UniversityShanghai 200072China key Laboratory of advanced display and system applications of Ministry of Education Shanghai UniversityShanghai 200072China

Indium phosphide(InP) quantum dots(QDs) have shown great potential to replace the widely applied toxic cadmiumcontaining and lead perovskite QDs due to their similar emission wavelength range and emission peak width but without intrinsic toxicity. Recently, electrically driven red and green InP-based quantum-dot light-emitting diodes(QLEDs) have achieved great progress in external quantum efficiency(EQE), reaching up to 12.2% and 6.3%, respectively. Despite the relatively poor device performance comparing with cadmium selenide(CdSe)-and perovskite-based QLEDs, these encouraging facts with unique environmental friendliness and solution-processability foreshadow the enormous potential of InP-based QLEDs for energy-efficient, high-color-quality thin-film display and solid-state lighting applications. In this article, recent advances in the research of the InP-based QLEDs have been discussed, with the main focus on device structure selection and interface research, as well as our outlook for on-going strategies of high-efficiency InP-based QLEDs.

关键词： indium phosphide quantum dots light-emitting diodes external quantum efficiency

Hydrothermal synthesis of uniform CdWO4:Eu^3+microrods as single component for UV-based WLEDs

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Journal of Rare Earths 2016年第12期34卷 1179-1187页

作者：雷芳殷录桥施鹰谢建军章蕾范灵聪 School of Materials Science and Enggineering Shanghai UniversityShanghai 200444China key Laboratory of advanced display and system applications Ministry of EducationShanghai UniversityShanghai 200072China

A series of single-composition emission-tunable CdWO4：Eu^3＋ uniform size nanorods were synthesized by polyvinylpyrrolidone（PVP） assisted hydrothermal process. The products were measured by powder X-ray diffraction（PXRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, photoluminescence, and fluorescent decay test. The results showed that reaction time, temperature, p H values and Eu^3＋ doped concentration played important roles in determining the morphologies and photoluminescent properties. And we also investigated its use in Ga N LED, warm-white-light could be obtained by the combination of the bright blue light originated from the charge transfer transition in the tungstate groups and the near UV light from LED chip with the red emission from 4f-4f transition of Eu^3＋, respectively. By properly tuning the doping concentration of Eu^3＋, chromaticity coordinates（0.30 0.22） could be achieved under the 380 nm excitation and its color rendering index was 80.6. So it has potential application in warm-WLED and replacing the commercial YAG：Ce phosphor which absence of red band emission.

关键词： CdWO4:Eu3+ hydrothermal synthesis WLED photoluminescence single-component rare earths