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Optical-transition Probability of Tm^(3+) Ions in Tm^(3+)/Er^(3+):YVO_4 Crystal

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Chinese Journal of Structural Chemistry 2004年第4期23卷 381-385页

作者：张莉珍王国富 taiju tsuboi Fujian Institute of Research on the Structure of Matter The Chinese Academy of SciencesFuzhouFujian 350002ChinaGraduate School of the Chinese Academy of SciencesBeijing 100039China Graduate School of the Chinese Academy of Sciences Beijing 100039China Faculty of Engineering Kyoto Sangyo UniversityKamigamoKita-KuKyoto 603-8555Japan

The polarized absorption spectra of Tm3+/Er3+:YVO4 crystal were measured at room temperature. Based on the Judd-Ofelt theory, the spectral parameters were obtained: the intensity parameters Wl of Tm3+ in Tm/Er:YVO4 crystal: W2 = 10.69×10-20, W4 = 0.604×10-20, W6 = 2.05×10-20 cm2 for the (100) face and W2 = 10.43×10-20, W4 = 0.13×10-20, W6 = 1.83×10-20 cm2 for the (001) face. Based on these values, the oscillator strength, radioactive lifetime and fluorescence branch ratio were calculated for Tm3+ in Tm/Er:YVO4 crystal.

关键词： spectral parameters Tm^(3+)/Er^(3+):YVO_4 crystal Judd-Ofelt theory

Simultaneous enhancement of efficiency and stability of OLEDs with thermally activated delayed fluorescence materials by modifying carbazoles with peripheral groups

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Science China Chemistry 2019年第3期62卷 393-402页

作者： Yunge Zhang Dongdong Zhang taiju tsuboi Yong Qiu Lian Duan Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of Chemistry Tsinghua University Department of Polymer Science and Engineering Zhejiang University

Albeit their high efficiencies, the operational stability of the organic light emitting diodes(OLEDs) based on thermally activated delayed fluorescence(TADF) emitters is still far from satisfaction, and few strategies have been proposed to improve their stability. Here, we show that by modifying the carbazole unit, one of the most commonly used donors in TADF emitters, with peripheral groups, both the device efficiency and operational stability can be greatly improved. Awell-known TADF molecule—4,5-di(9H-carbazol-9-yl)phthalonitrile(2CzPN) was chosen as the prototype and modified by introducing peripheral tert-butyl and phenyl groups to the 3,6-positions of the carbazole(named 2tBuCzPN and 2PhCzPN, respectively). The introduced groups not only improve the compounds' electrochemical stabilities referred to the cyclic voltammetry multi-sweep results, but also promote their photoluminescence quantum yields. Furthermore, reduced singlet-triplet energy gaps are observed, leading to the shortened exciton lifetimes which are benefit to suppress the exciton annihilations. Besides, the steric hindrance of introduced phenyl groups can partly restrain the concentration quenching of the TADF emitter. Consequently, OLEDs based on 2tBuCzPN and 2PhCzPN achieved improved maximum external quantum efficiencies(EQEs) of 17.0% and 14.0%, respectively(compared to 8.5% for 2CzPN). Meanwhile, 2PhCzPN based OLED showed reduced roll-off characteristics and a longer lifetime of 7.8 times higher than that of 2CzPN, testifying the effectiveness of subtle modification of the unstable moieties in simultaneous enhancement of efficiency and stability of OLEDs based on TADF emitters.

关键词： TADF OLED stability carbazole peripheral group

Investigation of emission properties of Tm^(3+) :Y_2O_3 transparent ceramic

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Chinese Optics Letters 2012年第9期10卷 67-71页

作者：易庆 taiju tsuboi 周圣明 Yosuke Nakai 林辉腾浩 Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences Faculty of Engineering Kyoto Sangyo University

A transparent and emitting ceramic of Y203 doped with 6% Tm3＋ ions is fabricated by vacuum sintering with ZrO2. Absorption, photoluminescence （PL）, and PL excitation （PLE） spectra are investigated in a spectral range of 200 to 2 100 nm at various temperatures between 296 and 12 K. Intense emission band appears at 450 to 465 nm in the visible range. Near-infrared emission bands are observed at 1 200 to 1 300 nm and 1400 to 1 550 nm, with intense peaks at 1270, 1450, and 1 523 nm. The luminescence mechanisms and potential applications of the emissions are discussed with the help of Judd-Ofelt theory and PLE spectra.

关键词： Tm Y2O3 transparent ceramic

Temperature effect on emission spectra and fluorescence lifetime of the ~4I_(13/2) state of Er^(3+)-doped Gd_2SiO_5 crystal

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Chinese Optics Letters 2011年第9期9卷 60-63页

作者：丁雨憧赵广军 Yosuke Nakai taiju tsuboi Key Laboratory of Materials for High Power Laser Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences Graduate University of Chinese Academy of Sciences Faculty of Engineering Kyoto Sangyo University

By measuring the emission spectra and the fluorescence lifetime of the ^4I13/2 state of Er^3＋ ions in Gd2SiO5 crystal at different temperatures, the effects of temperature on the spectra and the lifetime of the ^4I13/2 state are investigated. When the temperature increases, the emission line width for the ^4I13/2 →^4I15/2 transition is broadened, and the main emission lines at 1 596, 1 609, and 1 644 nm shifte toward shorter wavelengths. The measured lifetime of the ^4I13/2 state decreases from 13.2 to 8.4 ms with temperature increase from 13 to 300 K, which is mainly due to the temperature dependence of multiphonon relaxation between the ^4I13/2 and ^4I15/2 states and the changing population distribution among the Stark levels within the ^4I13/2 state. The experimental results imply that low temperature condition is better for the -l.6μm laser output.

关键词： Electromagnetic wave emission Emission spectroscopy Erbium Fluorescence Gadolinium Silicon compounds

Degradation Mechanisms in Blue Organic Light-Emitting Diodes

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CCS Chemistry 2020年第4期2卷 1278-1296页

作者： Dan Wang Cong Cheng taiju tsuboi Qisheng Zhang MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027

An organic light-emitting diode(OLED)is required to exhibit long-time operation without degradation as an inorganic LED.Sufficiently long operation time has been demonstrated for green-and red-emitting OLEDs.However,a blue device that is important for full-color display and lighting exhibits a much shorter operational lifetime than the other color devices.The short lifetime is mainly attributed to the molecular dissociation and the defects and radical species formation through various unimolecular and bimolecular processes,including direct photolysis,exciton–exciton interaction,and exciton–polaron interaction,and so on.

关键词： fluorescent organic light-emitting diodes phosphorescent organic light-emitting diodes thermally activated delayed fluorescence device degradation operational lifetime molecular dissociation

Photophysics and electroluminescence of phosphorescent organometallic compounds used for organic light emitting diodes

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Photophysics and electroluminescence of phosphorescent organ...

Energy transfer between Ir（ppy）3 dopant and TPD host observed from the photoluminescence intensity and lifetime of Ir（ppy）3

第11届全国发光学学术会议

作者： taiju tsuboi Faculty of Engineering Kyoto Sangyo UniversityKamigamoKyoto 603-8555Japan

Display based on organic light emitting diode(OLED)is the best candidate for creating flexible,full-color and thin fiat-panel display,because it is more functional than the current liquid-crystal fiat-panel display.The most peculiar advantage is the possibility of roll-up or conformal display on the curved surface.The OLED display is considered as a near-future display with high performance including high brightness,fast response and low voltage operation.

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Energy transfer between Ir（ppy）3 dopant and TPD host obser...

High color rendering index white organic light-emitting diode using levofloxacin as blue emitter

国际光子学、生物光子学和纳光子学研讨会

作者： taiju tsuboi Nadeer Aljaroudi Faculty of Engineering Kyoto Sangyo University KamigamoKyoto 603-8555Japan

Numerical calculation has been undertaken oil the temperature dependence of photolumineseenee (PL) intensity and PL lifetime of fac tris(2-phenylpyridine) iridium (Ir(ppy)3) phosphorescent material

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Chinese Physics B 2015年第5期24卷 577-582页

作者：苗艳勤高志翔张爱琴李源浩王华贾虎生刘旭光 tsuboi taiju Key Laboratory of Interface Science and Engineering in Advanced Materials Taiyuan University of TechnologyMinistry of Education Research Center of Advanced Materials Science and Technology Taiyuan University of Technology School of Physical Science and Electronics Shanxi Datong University College of Materials Science and Engineering Taiyuan University of Technology College of Chemistry and Chemical Engineering Taiyuan University of Technology Institute of Advanced Materials Nanjing University of Technology

Levofloxacin （LOFX）, which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes （OLEDs）. In this paper, the fabricated white OLED contains a 452-nm blue emitting layer （thickness of 30 nm） with 1 wt% LOFX doped in CBP （4,4＇-bis（carbazol-9-yl）biphenyl） host and a 584-nm orange emitting layer （thickness of 10 nm） with 0.8 wt% DCJTB （4-（dicyanomethylene）-2-tert-butyl-6-（1,1,7,7- tetramethyljulolidin-4-yl-vinyl）-4H-pyran） doped in CBE which are separated by a 20-nm-thick buffer layer of TPBi （2,2＇,2＂-（benzene-1,3,5-triyl）-tri（1-phenyl-lH-benzimidazole）. A high color rendering index （CRI） of 84.5 and CIE chromaticity coordinates of （0.33, 0.32）, which is close to ideal white emission CIE （0.333, 0.333）, are obtained at a bias voltage of 14 V. Taking into account that LOFX is less expensive and the synthesis and purification technologies of LOFX are mature, these results indicate that blue fluorescence emitting LOFX is useful for applications to white OLEDs although the maximum current efficiency and luminance are not high. The present paper is expected to become a milestone to using medical drug materials for OLEDs.

关键词： levofloxacin blue organic light emitting diodes white organic light-emitting diodes high color rendering index

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共聚物的合成及光物理性能研究

共聚物的合成及光物理性能研究