最新刊期
卷 33 ， 期 11 ， 2012
- 摘要：Eu2+doped, Dy3+ doped and Eu2+,Dy3+ co-doped high silica luminescence glasses were prepared. By controlling the doping concentration of Dy3+, the different mole ratios of Dy3+ to Eu2+ were researched. The effect of Dy3+ on luminescence properties of Eu2+,Dy3+ co-doped high silica glass was studied by means of excitation and emission spectra. The results show that nonradioactive energy transfer from Dy3+ to Eu2+ occurred in Eu2+,Dy3+ co-doped high silica glass. By co-doping with Dy3+, the covalent strength of the Eu-O bond weakened, which causes blue shift of the emission peak of Eu2+. With the increasing concentration of Dy3+, the energy transfer process from Dy3+ to Eu2+ is enhanced, and the emission intensity of Eu2+ increase. When the concentration of Dy3+ continued increase, the luminescence of Dy3+ decrease because of the effect of concentration quenching and the impaired energy transfer process from Dy3+ to Eu2+.关键词：high silica luminescence glass;Dy3+;Eu2+;energy transfer;concentration quenching93|123|4更新时间：2020-08-12
- 摘要：Gd2MoO6:Nd3+ nanophosphors was prepared with a solvothermal method using glycol-water mixed solution as a solvent, then calcined at 800℃ for 1 h. The samples were tested with X-ray diffraction, transmission electron microscope, emission and excitation spectrum. Uniform Gd2MoO6:Nd3+ nano-spher with good dispersity and efficient near infrared emission can be achieved at a reaction temperature as low as 800℃ and pH value of 1.5. The optimized Nd3+ doping mole fraction is 0.03. The ratio of water to ethylene glycol is 1:1. The particle is promising in the application of fluorescence immunoassay.关键词：solvothermal synthesis;infrared luminescence;Nd3+;Gd2MoO6103|94|0更新时间：2020-08-12
- 摘要：CdSe/ZnS core-shell QDs (523 nm) were used as emissive layers, poly-TPD as hole-transport layer (HTL) and ZnO as electron-transport layer(ETL). Green-emitting devices based on CdSe QDs were fabricated and characterized. Luminescence of semiconductor nanocrystal quantum dots (QDs) were used as luminescent centers in organic light emitting devices (OLEDs). By changing the size of QD, this OLED can emit visible to near-infrared spectrum with a narrow full-width at half-maximum (FWHM) of ~30 nm. However, the brightness, efficiency, and lifetime of LEDs need to be improved to meet the requirements of commercialization in the near future.关键词：light emitting diode;QD-LED;architecture;fabrication;characterization120|180|3更新时间：2020-08-12
- 摘要：At low temperature, primary charge separation in reaction centers of wild type rhodobacter sphaeroides show weak excitation wavelength dependence. It comes from the existence of the intramolecular charge transfer state. Herein, we find such kind of heterodimer mutant has more intramolecular charge transfer character and its excitation wavelength depend on temperature. The results show the excited state of heterodimer has two states (local and charge transfer) and they are strong coupling; Intramolecular charge transfer state is not favor to charge separation, as temperature decrease it becomes dark and charge separation yield decrease.关键词：reaction center;heterodimer;electron transfer81|276|0更新时间：2020-08-12
- 摘要：Two europium complexes with terephthalic acid or phenoxyethanoic acid as the first ligand and phenanthroline as secondary ligand are synthesized. Nanometer silver sol is prepared by using reduction method, then the using the silver particles were coated with silica by improved Stöber method. By controlling the dropping time and quantity of tetraethyl orthosilicate (TEOS), the thickness of SiO2 shell was controlled. Europium complexes are dissolved with DMF and then mixed with Ag@SiO2. So we obtain the core-shell nanoparticles composite luminescent materials Ag@SiO2. Results show that the obtained nano silver core has a size of about 50 nm and thickness of the SiO2 core is about 12 nm. This kinds of Ag@SiO2 can significantly enhance the fluorescence emission of europium complexes.关键词：Ag@SiO2 nanoparticles;europium complexes;fluorescence;enhancement86|26|1更新时间：2020-08-12
- 摘要：In the organic phase, hydrophobic CdSe/ZnS core-shell quantum dots (QDs) were synthesized successfully using a free-phosphine and non-injecction method. The transmission electron microscopy (TEM) shows CdSe/ZnS core-shell nanocrstals with an average diameter of 4.5 nm. The fluo- rescence quantum yield of the QDs, calibrated with fluorescein using a 470 nm laser, was found to be 29%, which was greatly increased compared with bare CdSe QDs, indicating strong photoluminescence. The maximum emission wavelength of QDs was 540 nm at excitation of 410 nm. Through the thin-film evaporation method, using the L-α-phosphatidylcholine and Cholesterol, the hydrophobic CdSe/ZnS core-shell QDs were successfully embedded in the two-layer of liposome. As the amphipathy of phospholipid molecules, rendering the luminescent hydrophobic CdSe/ZnS core-shell QDs hydrophilia, CdSe/ZnS core-shell QDs can be transferred in water without extra surface combining reagents. The morphology of liposome was characterized by TEM using negatively stained method, the process of CdSe/ZnS core-shell QDs embedded in the phospholipid two-layer was confirmed by inverted fluorescent microscopy under the UV light. The result indicates that CdSe/ZnS core-shell QDs embedded in the phospholipid two-layer have more photostability and more resistant photobleaching.关键词：CdSe/ZnS core-shell QDs;liposome;fluorescence90|186|0更新时间：2020-08-12
- 摘要：Using the flexible dipyridyl ligand 1,2-bis(4-pyridyl)ethane (bpe), a hybrid silver chloride [Ag3Cl3-(bpe)2]n(1) has been synthesized by ultrasonic method. The experimental results indicate that it belongs to triclinic system with space group P1. The structure of complex 1 features 1D (Ag6Cl6)n chains, which are further linked by bipodal spacers bpe to form a 2D bilayer structure. In addition, the complex 1 shows a strong yellow emission band that peaks at 525 nm (λex=385 nm) in the solid state at room temperature, and it is thermally stable below 170℃.93|113|0更新时间：2020-08-12
- 摘要：Considering the hydrostatic pressure and screening effect on the GaN/AlxGa1-xN quantum well with infinite barriers under an external magnetic field. The variational methods are used to numerical calculation the binding energies of the impurity in the system. The relations between the binding energies of donors with magnetic field strength and well width is given. We also discussed the difference between the cases with and without screening. The resultds indicate that the binding energy increases with the well width under a fixed magnetic field strength and pressure. The results also show that the binding energy increases with the magnetic field strength for a given well width and pressure. Because of the screening reduce coulomb interaction effectively, the binding energy of impurity states decreases significantly. Screening effect increases with the pressure and decreases with the magnetic field strength.关键词：quantum well;pressure;external magnetic field;screening;binding energy83|177|0更新时间：2020-08-12
- 摘要：The precursors of ZnO:Cu nano-powder were prepared in PVA aqueous solution. Then the products were obtained by calcining with different temperature. The effect of calcination tempe-rature on preparation and the photoluminescence of the ZnO:Cu nano-powder was investigated. The products dealed with different temperature were characterized by XRD, TEM and PL. The results of XRD indicated that when the clacination temperature was above 500℃, the products had a crystal structure of hexagonal wurtzite, while the polymer PVA decomposed completely. The TEM result showed that the nano-powder was spherical with a uniform size of 20~25 nm and good dispersibility. Two blue emission peaks centered at 458 nm and 486 nm were observed in the room temperature PL spectra excited with 342 nm light. The product calcined in 400℃ had the most strongest blue emission, while the green emissions (510~530 nm) became weak and changed into blue emission. With the clacination temperature increasing, the violet-blue spectral had an obvious red shift from 404 nm to 422 nm. The emission intensity increased firstly and then decreased.关键词：zinc oxide;doping;PVA;calcination temperature;photoluminescence86|235|0更新时间：2020-08-12
- 摘要：Tm3+ doped organic-inorganic materials were fabricated with ethyl silicate and 3-glycidyloxypropy-trimethoxysilane as precursors by sol-gel method. According to the Judd-Ofelt theory, the Judd-Ofelt strength parameters(Ω2, Ω4, Ω6)were calculated in terms of the characteristics of the absorption spectra and the physical-chemical properties. Meanwhile, according to the McCumber theory, the absorption and stimulate emission cross-section corresponding to the 3H6←→3F4(1.8 μm) transition of Tm3+ were also calculated. The gain cross section was calculated by using the emission cross-section, absorption cross-section and Tm3+ concentration. These Tm3+-doped organic- inorganic materials would have a potential application in mid-infrared lasers at about 1.8 and 2.0 μm wavelength.关键词：Tm3+ ions;organic-inorganic material;optical spectra;gain properties102|98|0更新时间：2020-08-12
- 摘要：Undesirable surface effect of luminescent upconversion nanoparticles (UCNPs) is a major obstacle to the biomarker. In this work, we synthesized the water-soluble NaYF4:Yb3+, Er3+ UCNPs with amino functional groups and polyethylene glycol (PEG) molecules modified by covalent coupling of the way to the surface of UCNPs. The spectral characterization showed that the luminescent properties of UCNPs unchanged. Scanning electron microscopy results indicate that modification of PEG molecules distinctly reduce the aggregation of UCNPs. The cell toxicity experiments show that this modification on the UCNPs has good biocompatibility.关键词：luminescent upconversion nanoparticles;polyethylene glycol;surface modification111|231|1更新时间：2020-08-12
- 摘要：Red-emitting phosphors (Sr1-x-yBax)3Al2O6:3yEu2+ were synthesized by a solid-state reaction in a reducing atmosphere. X-ray diffraction and fluorescence spectrophotometer were used to investigate the effects of doping Eu2+ and Ba2+ ions on the crystal structure, luminescence properties and thermal stability of the samples. The XRD results indicate that the samples prepared at 1 200℃ for 3 h generate a single Sr3Al2O6 phase with cubic system and Pa3 space group. The crystal structure type of the host has not been changed by doping Eu2+ and Ba2+ ions. The emission spectra illustrate that the emission intensity of (Sr0.98-yBa0.02)3Al2O6:3yEu2+ reaches the maximum when the mole fraction of Eu2+ is 4%. Furthermore, the emission peaks of (Sr1-x-yBax)3Al2O6:3yEu2+ show a red shift and decrease of emission intensity compared with Sr3(1-y)Al2O6:3yEu2+ under the excitation of 460 nm. Both of them have broad emission bands due to the 4f65d1→4f7 transition of the Eu2+ ions. Finally, the thermal stability of Sr3Al2O6:Eu2+ is enhanced by doping Ba2+ ions.关键词：(Sr1-xBax)3Al2O6;solid-state reaction;red phosphor;luminescence properties;thermal quenching97|92|1更新时间：2020-08-12
- 摘要：Mercury cadmium telluride films were prepared by RF magnetron sputtering technique at different sputtering pressure on glass substrate. In experiment, X-ray diffraction (XRD), atomic force microscopy (AFM) and energy dispersive spectroscopy (EDS) have been used to characterize the microstructure, surface morphology and chemical composition of Hg1-xCdxTe films. Experimental results show that the growth rate, crystal structure, chemical composition content and surface morphology of the Hg1-xCdxTe films have a strong relation to the sputtering pressure. When increased the sputtering pressure, the growth rate of films decreased. When the sputtering pressure was more than 1.1 Pa, the prepared Hg1-xCdxTe film was amorphous, and when the sputtering pressure was controlled at 0.9 Pa, the films exhibited polycrystalline structure. In addition, the surface roughness (RMS and Ra) of Hg1-xCdxTe films gradually decreased with the increasing of sputtering pressure. The chemical composition of films also varing with different sputtering pressure, the Hg and Hg+Cd content in films reache the lowest, but the Cd content gets to the top at 1.1 Pa.关键词：Hg1-xCdxTe films;amorphous semiconductors;microstructure;surface morphology;magnetron sputtering84|66|0更新时间：2020-08-12
- 摘要：ZnO films were grown on flexible substrate by the atomic layer deposition (ALD) using diethyl zinc (DEZn) as a metal precursor and water as a reactant. AFM, XRD and HALL effect were used to investigate the morphology, structural and electrical properties of the films. PL spectrum was measured for optical property. With the increasing temperature, the crystal quality and optical property of the films were improved. When grown at 170℃, the films exhibited c-axis orientation, the electron concentration was 5.62×1019 and the electron mobility was 28.2 cm2·V-1·s-1.关键词：ZnO;ALD;growth temperature;flexible substrate130|111|0更新时间：2020-08-12
- 摘要：Insulation layer of aluminum substrate for LED encapsulation was made by hard anodizing technology. White and blue GaN-based light-emitting diodes were encapsulated on the aluminum plate directly. White LED was fabricated by blue chip coated with YAG:Ce phosphor, while blue LED didn't coated with phosphor. Accelerated aging tests at 500 mA and 700 mA were carried out for about 1 000 h on the new type of integrated high-power. Then optical parameters of LEDs were tested per 24 h. Compared with the blue and white LED, we could get the following conclusions: White LED luminous flux attenuates seriously than the blue LED, while optical power is opposite. There are two stages in LED attenuation: The chip and phosphor decay at the same time in initial stage of aging, well blue chip attenuation is dominant after a certain period of time.关键词：integration package;LED;aging;failure mechanism108|437|8更新时间：2020-08-12
- 摘要：We present a design of 2D photonic crystal coupled-cavity waveguide with a high transmission efficiency and a quality factor simultaneously. By optimizing the structural parameters such as amount and radius of air holes between microcavities and waveguide, a 90% transmission efficiency is obtained with a Q factor of 8.20?104. In order to increase Q factor without sacrificing too much efficiency, a new kind of coupled-cavity waveguide is formed by introducing microcavity chains. Photons hop in adjacent microcavies. For this new kind of waveguide, Q factor is improved one order higher and transmission efficiency only decrease by 40%. The result has a practical gui-ding significance for application of photonic crystal in various different fields such as slow light, light trap, optical transmission.关键词：two dimensional photonic crystal coupled cavity waveguide;Q factor;transport property82|246|2更新时间：2020-08-12
- 摘要：The heating distribution of vertical cavity surface emitting laser array (VCSEL) is analyzed. The heating source is simplified and the heat transport model is established. The Comsol Multiphysics software is used for all numerical simulations. The temperature rise is computed by changing the cell diameter and gap between the adjacent cells. Three kinds of arrays are manufactured: 4×4, 5×5 and 8×8. The power are 580, 1 440 and 2 100 mW, the corresponding power density are 115, 374 and 853 W/cm2, respectively. The values of temperature rise at 4 A are 120, 58 and 38℃, which are obtained by redshift of wavelength. The arrays made up of small size cells can effectively reduce the thermal crosstalk and improve the output power.关键词：vertical cavity surface emitting laser array;high power;thermal crosstalk115|154|0更新时间：2020-08-12
- 摘要：OLEDs were fabricated with a structure of anode (ILTO or ITO)/NPB (70 nm)/Alq3 (60 nm)/LiF (1 nm)/Al (100 nm). NPB and tris(8-hydroxyquinoline) aluminum (Alq3) were used as hole transport layer and light emitting layer, respectively. A buffer layer of lithium fluoride (LiF) capped with aluminum (Al) was used as a cathode. Comparing with ITO-anode device, the luminance, current efficiency, power efficiency, and external quantum efficiency (EQE) are obviously enhanced in ILTO-anode device. Simultaneously, the turn-on voltage (2.1 V) is decreased in combination with a better rectifying behavior. The significant improvement in the EL performance indicates that the high-work-function ILTO anode can not only lower the hole-injection barrier, but also leads to a better charge balance in OLEDs. The effects of high work function afford more opportunities to develop and optimize the performance of organic photoelectric devices, and facilitate the fabrication process of devices.关键词：work function;doped;transparent conducting oxides;OLED84|164|0更新时间：2020-08-12
- 摘要：We systematically investigated the stability of gallium indium zinc oxide (IGZO) thin film transistor (TFT) with reactive sputtered SiOx insulator under white light illuminaion. The research involved an overall stress conditions that included light stress (LS), negative voltage stress (NBS), positive voltage stress (PBS), negative bias-light stress (NBLS), and positive bias-light stress (PBLS). The results demonstrate a large threshold voltage shift under LS and NBLS conditions, and a negligible threshold voltage shift under PBLS condition. The C-V characteristics indicated that the shift of threshold voltage came from traps generated at or near the dielectric/semiconductor interface. Additionally, the stretched exponential model was used to obtain the relaxation time. This work aimed to provide an instability origin of IGZO-TFT under white light illumination and gate voltage bias.关键词：thin film transistor;stability;reactive sputtered SiOx85|64|0更新时间：2020-08-12
- 摘要：The SiO2 film has been successfully synthesized by liquid phase deposition (LPD) method. The microstructure and passivation performance of the SiO2 film have been investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and microwave photoconductive decay (μ-PCD). The results show that the deposited SiO2 film contains a little amount of F element and it is very smooth and dense. The reflectance and surface recombination velocity reduced to 10.88% and 2 830 cm/s, respectively.关键词：liquid phase deposition;SiO2 film;passivation121|103|0更新时间：2020-08-12
- 摘要：The interaction between ethyl piperate and bovine serum albumin (BSA) was deeply investigated by using fluorescence spectroscopy (FS). The experimental results showed that the ethyl piperate molecules quenched the intrinsic fluorescence of BSA by forming ethyl piperate-BSA complex. The mechanism of fluorescence quenching was confirmed combining by both static quenching and non-radiation energy transferring. The quenching constants (Kq) are 1.451×1013 L·mol-1·s-1(25℃) and 1.136×1013 L·mol-1·s-1 (37℃). The apparent binding constants (KA) between ethyl piperate and BSA are 9.484×105 L·mol-1 (25℃) and 1.355×106 L·mol-1(37℃), and the value of binding sites (n) are 1.18(25℃) and 1.24(37℃). According to the Förster theory of non-radiation energy transfer, the binding distances (r) were 2.68 nm (25℃) and 2.81 nm (37℃). The process of binding was a spontaneous molecular interaction in which entropy increased and Gibbs free energy decreased, indicating that the interaction of ethyl piperate and BSA was driven mainly by hydrophobic force. The effects of metal ions on the interaction of ethyl piperate with BSA were also discussed.关键词：fluorescence spectroscopy;ethyl piperate;bovine serum albumin;metal ions;effect95|131|2更新时间：2020-08-12
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