最新刊期
卷 41 ， 期 11 ， 2020
- 摘要：YAG:Ce fluorescent films have high luminous efficiency, good thermal stability, and fast heat dissipation, which have broad practical application prospects in the field of high-power white lighting and laser-driven white lighting. This article reviews the recent research on the preparation and performances of YAG:Ce polycrystalline films, single crystal films, and composite films. The future applications of YAG:Ce films in high performance WLED and laser-driven white lighting are also proposed.关键词：films;YAG:Ce;single crystal;polycrystalline;laser
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发布时间：2020-11-10
Invited Review
- 摘要：Disciplines of modern science are both highly differentiated and highly integrated. The multidisciplinary integration has greatly promoted the progress of science, results in new research paradigms and transformative technologies. Based on the author's research experience on perovskite light-emitting devices, this paper expounds the role of multidisciplinary integration in promoting the development of perovskite luminescence.关键词：perovskites;light-emitting diodes;luminescent materials;electroluminescence;multidisciplinary integration
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发布时间：2020-11-10 - 摘要：In the past two decades, we have witnessed the fast advances of cancer phototherapy, which tightly relies on the development of a large variety of photo-functional nanomaterials with outstanding photothermal conversion or photosensitization capacities, and has showed great promising for future clinical translation. Based on our own experimental experiences, we herein offer our perspectives on the challenges and opportunities, which would be faced in the future clinical translation of such photo-functional nanomaterials mediated cancer phototherapy. We encourage the researchers in this field to dissolve these problems hindering the clinical translation of cancer phototherapy, and work together to promote their clinical translation, thereby benefiting the cancer patients in clinics.关键词：photo-functional nanomaterials;cancer phototherapy;photothermal therapy;photodynamic therapy
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发布时间：2020-11-10
40th Anniversary Special Column——Young Scientist on The Road
- 摘要：Different series of Pr3+ doped GeSe2-Ga2Se3-CsI(GGC)chalcogenide glass were prepared by a melt-quenching method. Under the excitation of 2.0 μm wavelength, the emission spectra of bulk glass (2 mm) and glass column(6 mm) were compared. The intensity parameter Ωi(i=2, 4, 6) and radiative lifetime τrad of Pr3+ doped Ge-Ga-Se-CsI chalcogenide glass are calculated and analyzed by Judd-Ofelt theory. The fluorescence lifetime of the glass(0.5% Pr 3+:3.08 ms) was measured by fitting the decay curve. The fabricated fiber has a double cladding structure, the fiber loss is measured by cut-back method and the minimum loss at 7.6 μm is 2.27 dB/cm.关键词：Chalcohalide glass;Judd-Ofelt theory;Radiative lifetime;Fiber loss
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发布时间：2020-11-10 - 摘要：The alkali ions(Li+/Na+/K+) co-doped MgSc2O4:Er3+/Yb3+ nanocrystals have been synthesized by hydrothermal method. The average size of obtained spheroid nanocrystals is about 35 nm. The upconversion luminescence intensity can be strengthened by adjusting alkali ions types and contents. The K+ ions co-doped MgSc2O4:Er3+/Yb3+ nanocrystals display the strongest luminescence. As K+ content increasing, emission intensity can be enhanced gradually due to the large asymmetry of crystal field created by K+ ions. The spectral properties of K+ ions co-doped MgSc2O4:Er3+/Yb3+ nanocrystals are described in detail as a function of Er3+ and Yb3+ concentrations. The MgSc2O4:1%Er3+/5%Yb3+ nanocrystal was optimized for the strongest upconversion luminescence. Then, the upconversion mechanism and energy transfer processes between Yb3+ ions and Er3+ ions in K+ ions co-doped MgSc2O4:Er3+/Yb3+ nanocrystals were investigated under the 980 nm excitation.关键词：upconversion luminescence;rare earth ion;Alkali ions;hydrothermal method;MgSc2O4
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发布时间：2020-11-10 - 摘要：The Nd3+-sensitized Ca2+-doped NaYF4:Yb/Tm/Ca@NaGdF4:Nd/Yb core/shell upconversion nanoparticles were successfully prepared by solvothermal method. The effects of key factors such as the content of sensitizers Nd3+ and Yb3+ and the excitation power on the fluorescence performance were studied for the blue light and UV up-conversion emission generated in the Tm3+ multi-photon process. To obtain up-converting nanoparticles with good hydrophilicity, the UCNPs surface was modified with mesoporous silica(mSiO2). Its morphology, structure and fluorescence properties were characterized by TEM, XRD, FT-IR and fluorescence spectroscopy. The results showed that the prepared nanoparticles were pure hexagonal phase, the surface was evenly modified with a layer of mSiO2. Then, under the excitation of 808 nm near infrared light, when the mole fraction of Nd3+ and Yb3+ in the shell was 50% and 10% respectively, it shows strong up-conversion blue light(1D2→3F4, 1G4→3H6) and ultraviolet light(1I6→3F4, 1D2→3H6). The research will have potential application prospects in photodynamic therapy and fluorescence imaging.关键词：Nd3+ sensitization;multiphoton emission;core-shell structure;silica
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发布时间：2020-11-10 - 摘要：In order to optimize the influence of reaction process on the quality of synthesized perovskite quantum dots(QDs) and the QDs thin films, cesium acetate is used as the raw material for the synthesis of precursors because of its better solubility than cesium carbonate. A series of properties of quantum dots and films prepared under different conditions were characterized. CsPbBr3 all-inorganic perovskite quantum dots were synthesized by heat-injection with different reaction temperatures and reaction times. The CsPbBr3 quantum dot films were prepared via different spin coating rates and annealing times. X-ray diffraction, absorption spectrum, fluorescence lifetime and TEM tests were carried out on the prepared QDs and the photoluminescence properties of the QD films were characterized. CsPbBr3 all-inorganic perovskite quantum dots were prepared by using cesium acetate with better solubility as the raw material for synthesis. It is found for the reaction temperature of 180℃ and the reaction time of 5 s, the quantum dots have smaller size of 8 nm and longer fluorescence life of 8 ns with high crystal quality and absorption characteristics. CsPbBr3 QD films prepared with rotation coating speed of 3 000 r/min and annealing time of 10 min have higher photoluminescence intensity and smaller full width at half maxima. Compared with quantum dot materials synthesized from cesium carbonate at the same conditions, quantum dots synthesized from cesium acetate as raw materials and the QD films have better optical properties.关键词：perovskite;CsPbBr3;quantum dot;XRD;PL
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发布时间：2020-11-10 - 摘要：All inorganic perovskite nanocrystals have broad application prospects in functional optical materials and optical devices due to their high quantum yield, narrow line width and full band visible light emission characteristics. The effect of solvent density, polarity and viscosity on the reaction process, crystal structure, microstructure and optical properties of CsPbBr3 perovskite nanocrystals was studied in this work. The results show that the growth of CsPbBr3 perovskite nanocrystals in the upper, lower and whole liquid phase of the reactor can be realized by changing the density of the reaction solvent. The higher the polarity of the solvent, the lower the crystallinity, the lower the luminescence intensity and stability. High solvent viscosity is not conducive to the preparation of high quality CsPbBr3 perovskite nanocrystals. The method proposed in this paper is expected to further improve its application in solar cells, lasers, photodetectors and light-emitting diodes.关键词：CsPbBr3;liquid-phase precipitation;solvent;perovskite
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发布时间：2020-11-10 - 摘要：A novel D-A-D bipolar compound with pyrimidine as electron acceptor and carbazole derivative as electron donor, namely 1, 3-dihydro-3, 3-dimethyl-1-(2-(3-(9-phenyl-9H-carbazol-3-yl)phenyl)pyrimidin-5-yl) indeno[2, 1-b]carbazole (DMIC-PmPCP), was synthesized and characterized by1H NMR. DMIC-PmPCP was used as host material for bis(2-methyl-6-phenylpyridine)(2-([1, 1'-biphenyl]-3-yl)pyridine)iridium (GD-01) in fabricating high efficiency phosphorescent organic light emitting diode(OLED). The device gave a green emission with CIE coordinate of (0.33, 0.62) and maximum current efficiency of 70.16 cd·A-1 was obtained. It also exhibits high current efficiency of 55.08 cd·A-1 at luminance of 3 000 cd·m-2, which is about 17.4% more than the current efficiency of similar structural OLED with 1, 3-dihydro-3, 3-di-methyl-1-(3-(4, 6-diphenyl-1, 3, 5-triazin-2-yl)phenyl) indane[2, 1-b]carbazole(DMIC-TRZ) as the host material. DMIC-PmPCP was also used as host material for Tri(2-phenylpyridine)iridium(Ir(PPy)3) in fabricating green PhOLED, the device exhibited high current efficiency of 52.33 cd·A-1 at luminance of 3 000 cd·m-2. The more balanced carrier transport plays a key role for excellent device performance and making DMIC-PmPCP a promising candidate as the host material for green PhOLEDs.关键词：bipolar;host material;green light;organic phosphorescent
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发布时间：2020-11-10
Synthesis and Properties of Materials
- 摘要：Self-powered photodetectors operating without any power supply are urgently needed in modern optoelectronic devices from the perspective of energy saving, portability and miniaturization. In this work, a novel heterojunction structure based on p-type selenium nanocrystalline flowers(Se-f) and p-type polyaniline(PANI) was prepared by in-situ polymerization. The high surface area of Se-f structure can absorb more light energy, which is conducive to the effective separation of hole electron pairs. PANI nanorods are deposited directly on Se-f surfaces to form high-quality heterojunctions, which enhance the generation of hole electron pairs. Se-f/PANI photodetector exhibits good light response in range of 300-700 nm under 0 V bias, especially under 610 nm light with the highest responsivity(72.9 mA·W-1), good detection rate(1.98×1012 Jones), and fast response(rise time of 8.6 μs and decay time of 3.24 ms). This work will provide a new way for the development of high-performance energy-saving organic/inorganic optoelectronic devices in the future.关键词：selenium nanocrystalline flowers;polyaniline;photodetectors;self-powered
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发布时间：2020-11-10 - 摘要：In this paper, polyethylenimine(PEI) was introduced into inverted white light-emitting diodes(IOLEDs) with the structure of ITO/ZnO/PEI/EML/TAPC/MoO3/Al. The effects of PEI as a surface modification layer on the performance of devices were investigated. It is found that the introduction of PEI can effectively reduce the work function of ZnO electron injection layer and control the electron injection of devices, improving the hole and electron injection balance. At the same time, it can passivate the surface defect states of ZnO and reduce exciton quenching. When the concentration of PEI is 1.0 mg/mL, white IOLEDs possess the optimal performance, with the largest brightness of 11 720 cd·m -2 and efficiency of 16.0 cd·A-1 respectively. The introduction of PEI modified layer lays a foundation for the further research of inverted OLEDs with high performance.关键词：polyethylenimine(PEI);interface modification;Solution processing;inverted white OLED
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发布时间：2020-11-10
Device Fabrication and Physics
- 摘要：The emission properties of CuInS2/ZnS quantum dot optical fibers(QD-OFs) were theoretically calculated under the two-level system approximation, and the transmission of QD emission along the optical fiber was obtained under different QD fluorescence lifetime, Stokes shift and absorption-emission cross section(AECS). The results showed that when the three parameters were fixed, the emission intensity of QD-OFs increased with the increasing fiber length, but all of them eventually tended to saturation or decreased. When the fiber length was fixed, the relative intensity of the fiber emission was changed by 7.1, 10.52 and 2.8 for each change of the fluorescence lifetime, Stokes shift and AECS by 1 time. Therefore, Stokes shift had the greatest influence on the OF emission intensity, followed by the fluorescence lifetime, and the least influence was the AECS. However, the AECS had the greatest influence on the spectral peak position. In the 80 cm OF, the spectral redshift was 5.36 nm when the AECS increased by 1 time. The variation trend of emission intensity with fiber length calculated by theory accorded with the experimental data in the literature. This paper provides a practical method for the selection of doped materials in QD-OFs.关键词：quantum dot fiber;fluorescence lifetime;absorption-emission cross-section;Stokes shift
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发布时间：2020-11-10
Theoretical Calculation and Spectral Analysis
- 摘要：Ce:Y3Al5O12(Ce:YAG) transparent phosphor ceramics were fabricated by solid state reaction method through vacuum sintering. The effects of thickness(0.3~2.3 mm) and surface roughness(322.86 nm, 9.79 nm) of the ceramics on correlated color temperature, color rendering index, and photoelectric conversion efficiency were studied under the excitation of high power blue LED chip(3.2 V×0.3 A) and blue LD lighting(0.8 W, 1.6 W). The luminescence property can also be improved by tuning the surface roughness of the ceramics, the Ce:YAG transparent ceramics with a roughness of 322.86 nm obtained high luminescence efficiency of 93.6 lm/W(blue light LED excitation) and 178.5 lm/W(blue light LD excitation), respectively. The results show that the luminescence performance of high power density solid-state lighting devices can be effectively improved by adjusting the thickness and surface state of Ce:YAG transparent ceramics.关键词：Ce:YAG;transparent ceramics;high-power LED;LD lighting;photoelectric conversion efficiency;thickness;surface roughness
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发布时间：2020-11-10 - 摘要：Eight and four 1.125 mm×1.125 mm(45 mil×45 mil) flip-flop blue LED chips were eutectic on an 8-core ceramic package substrate with a size of 5.80 mm×2.55 mm×0.50 mm. Six and three chips of the same specification were co-crystallized on a 6-core substrate of 4.15 mm×2.55 mm×0.50 mm. The high reflection white wall glue was coated on the side of some sample chips, and the effect of white wall glue on the optical power of the device was studied. White light devices were fabricated by coating silica gel mixed layer on the top surface of the chip partially coated with white wall glue. The effects of the number of eutectic chips and the position of the eutectic on the optical power, luminous flux and color temperature of the blue and white light devices are studied. The results show that the matching degree between the number of eutectic chips(rated power) and the ceramic substrate area, and the matching degree between the thermoelectric separation metal layer of ceramic substrate and the eutectic position of the chip can significantly affect the luminous performance of ceramic packaged LED.关键词：ceramic packaging;gold tin eutectic;thermal balance;thermoelectric separation
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发布时间：2020-11-10 - 摘要：The failure mechanism of leakage in LED samples was studied. Since leakage has a negative impact on LED quality, it is necessary to analyze how the process works on the leakage. Two groups of failure samples were selected for study. Through testing, there are abnormal leakage at the positive electrodes under the emission microscope. The section of the sample was prepared by fully automated argon ion polishing system and observed by scanning electron microscope. SEM observation showed that in the chips there were holes in electrodes and obvious cracks in the epitaxial layer corresponding to the holes. According to the analysis, electrode cavity is generated during welding. In the subsequent high-temperature reflow welding, packaging also using process, pressure and stress are concentrated at the crack, which causes damage of GaN epitaxial layer and leads to electric leakage. It provides a good reference scheme for LED chip leakage detection means and mechanism analysis. What's more, it provides a theoretical reference direction for reducing chip cracks and holes.关键词：light emitting diode;failure analysis;leakage;static
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发布时间：2020-11-10
Luminescence Industry and Technology I Frontier
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