最新刊期
卷 40 ， 期 6 ， 2019
- 摘要：Carbon dots(CDots) as a novel carbon-based fluorescent nanoparticles have attracted a lot of attention due to their distinctive advantages such as tunable emission, high photostability, biocompatibility, and low cost. In the past decade, preparation and application of CDots have been made great progress. However, the accurate photoluminescence(PL) mechanisms of CDots are controversial due to the diversity of the precursor and the synthetic method. Now it is generally accepted that the optical properties of CDots originate from core state(π-π*), surface edge state(n-π*), molecular fluorophores or their combination. We will discuss them successively in the following part. In this review, firstly we summarize the photoluminescence origins of CDots, then discuss the methods to modulate the bandgap by particle size modification and surface structure engineering respectively. This is followed by introduction of the enhancement of PLQY. The most effective applications of CDots in optoelectronic devices, information storage, bioimaging and cancer treatment are also mentioned. This review concludes with an outlook on the development and application prospects of CDots.关键词：carbon dot;photoluminescence mechanisms;bandgap modulation;bioimaging;white-light-emitting devices271|349|0更新时间：2020-08-12
- 摘要：A series of La2-xMgTiO6:xDy3+ and La2-x-yMgTiO6:xDy3+,yEu3+ phosphors were synthesized by high temperature solid-state method. The phase of the products was determined by X-ray diffraction meter and the composition of the phosphors was optimized. The influence of the concentration of Dy3+ and Eu3+ on the luminescence intensity was studied. The fluorescence spectra and fluorescence lifetime of the phosphors were tested. The energy transfer mechanism and energy transfer efficiency between Dy3+ and Eu3+ were studied. The results showed that all the as-synthesized doped phosphors were of single phase. The optimum doping concentration of Dy3+ in La2-xMgTiO6:xDy3+ was x=0.05. The La2-x-yMgTiO6:xDy3+,yEu3+ phosphors exhibited yellow and blue emissions of Dy3+ and characteristic emissions of Eu3+ upon 350 nm near ultraviolet light excitation. The fluorescence lifetime decay of Dy3+ was double exponential and it decreased with the increase of the concentration of Eu3+, which showed the occurrence of an energy transfer between Dy3+ and Eu3+. The energy transfer efficiency increased with the increase of the concentration of Eu3+, which was 53.9% for La1.83MgTiO6:0.05Dy3+,0.12Eu3+. By adjusting the concentration of Dy3+ and Eu3+, the phosphor realized the emission from cold-white-light to warm-white-light. The chromaticity coordinates of La1.83MgTiO6:0.05Dy3+,0.12Eu3+ were (0.3373, 0.3544).关键词：LED;white phosphor;double perovskite;titanate175|79|7更新时间：2020-08-12
- 摘要：The AlN thin films with (002) preferred orientation was deposited on the glass substrate by DC magnetron reactive sputtering method under different nitrogen concentration. The structure and surface pattern of AlN films were characterized by X-ray diffraction(XRD) and scanning electron microscope(SEM). The luminescence properties of AlN thin films were also investigated by photoluminescence(PL) spectra. The results show that the AlN thin films deposited under different nitrogen concentration all present (002) preferred orientation with uniformly dense surface and the average size of the grains is about 20 nm. The PL spectra shows that the AlN thin films deposited under different nitrogen all have a strong emission at 550 nm originating from the defect of VAl transiting to the VB. There are several weak defect emissions at 589, 614, 654 nm. These defect emissions become more obvious with the N2 concentration increasing. The weak emissions at 589, 614, 654 nm can be ascribed to transition from ON-ON to VAl-2ON, from CB to oxygen impurities(IO) and from VAl-ON to VB respectively.关键词：magnetron sputtering;preferred orientation;photoluminescence;defect emission180|775|0更新时间：2020-08-12
- 摘要：NaMg4-xCax(VO4)3:0.01Eu3+(x=0~2), NaMg2.1Ca1.9-y(VO4)3:yEu3+(y=0~0.19), NaMg2.1Ca1.9-y(VO4)3:yEu3+,yX-(X=Cl,F) and NaMg2.1Ca1.9-2y(VO4)3:yEu3+,yM+(M=Li, Na, K) phosphors have been synthesized by high temperature solid phase method. X-ray diffraction(XRD), scanning electron microscopy(SEM) and photoluminescence spectra were utilized to characterize the samples. The results show that the NaMg2Ca2(VO4)3 cubic phase phosphor can been effectly excited by UV light, and emit the blue green light of vanadate ions and the red light of europium ions simultaneously. The effect on the luminescence properties of VO43- and Eu3+ by adjusting matrix composition and charge compensation by F-, Cl-, Li+, Na+ and K+ ions, the energy transfer from VO43- to Eu3+, and the energy transfer mechanism have been discussed. Charge compensators can increase the emission intensity of Eu3+ and decrease the luminescence intensity of the substrate significantly, indicating that the charge compensators enhance the energy transfer between the substrate and activator ions. The emission intensities of the blue green and red light can be controlling, and a single base white light phosphor was obtained.关键词：vanadate matrix;luminescence of the matrix;luminescence of the Eu3+;charge compensation;single phase white light147|71|1更新时间：2020-08-12
- 摘要：A series of neutral cyclometalated iridium(Ⅲ) complexes(Ir1-Ir5), which containing 2-phenylpyridine main ligand and fluorinated picolinic acid ancillary ligands, were synthesized with main ligand of 2-phenylpyridine and ancillary ligand of 2-pyridine carboxylic acid. The structures of the complexes were confirmed by the NMR and mass spectroscopies. All these complexes displayed intense green phosphorescent emission with the emission maximum between 498 nm and 516 nm. The quantum efficiency of reference complex Ir1 is 32.0%. Due to the influence of the 2-position fluorine substituent, complex Ir4 has the lowest quantum efficiency of 6.0%. The quantum efficiency of other fluorinated complexes are between 13.0% and 16.0%. Compared with the reference complex Ir1, the oxidation potential of fluorinated complexes increased from 511 mV to 547-574 mV and the thermal stability enhanced from 142℃ to 187-380℃. The thermal stability increase of Ir4 is the minimum(187℃). The ECL intensity of reference complex Ir1 was 332. Except Ir4, the ECL intensity of complexes Ir2-Ir5 is higher than reference complex Ir1, which is between 333 and 370. Complex Ir4 has the lowest ECL intensity of 203. All these results show the influence of fluorine substituent is related to the substituent positions in picolinic acid. The 2-position fluoro-substitution can reduce the quantum efficiency and thermal stability because of the steric effect. Relatively, fluoro-substitution on other positions can enhance these two performances. This research can be used as a reference in the design and development of efficient luminescent materials.关键词：cyclometalated iridium(Ⅲ) complex;pyridine carboxylic acid;fluorine;electrochemiluminescence145|175|0更新时间：2020-08-12
- 摘要：Two types of plasmonic nanostructure i.e. the ultra-thin gold nanoshell and the sputtered gold nanofilm combined with upconverting nanocrystals are designed and fabricated. The enhancing effect of gold nanoshells on the upconversion luminescence (UCL) and the quenched UCL induced by the gold nanofilm are observed, respectively. The wavelength dependent enhancement and quenching mechanisms are elucidated on the basis of the microstructure characterizations, steady state and transient spectral analysis. Green emission of Ho ions has been selectively enhanced by the ultra-thin gold nanoshell outside of NaYF4:Yb, Ho,Fe nanocrystals, and the excitation enhancement mechanism is stemmed from the coupling of LSPR with NIR excitation energy. In contrast, sputtered gold film on the top of the NaYF4:Yb,Er@SiO2 nanocrystal exhibits the quenching effect, likely originating from the scattering of the excitation light and the increase of nonradiative transition probability of the green emission state due to its coupling with LSPR absorption band, which is responsible for the decline of UCL intensity as well as the shortened green UCL lifetime.关键词：upconversion luminescence;gold nanoshell;localized surface plasmon;luminescence quenching;gold nanofilm143|242|2更新时间：2020-08-12
- 摘要：In order to study the impact of nitrogen-doping on the photoluminescence properties of carbon nanodots and explore a facile preparing approach for nitrogen-doping carbon dots(N-CDs), 2-aminoterephthalic acid as the precursor and various modifiers were firstly dissolved in deionized water. Thereafter the as-prepared solution was treated by microwave irradiation of 1 kW for 3 min and consequently a novel N-CD was obtained by the one-pot method. Experimental results indicated that the as-synthesized N-CDs were very soluble in water and exhibited bright blue emission under ultraviolet light. Furthermore, the fluorescence emission was independent of excitation wavelengths. The N-CDs showed an approximately spheric particle with a size of 5-8 nm and an obvious fringe distance of 0.23 nm, close to the (100) crystal lattice distance of graphitic carbon structure. The fluorescence of the obtained N-CDs could be effectively quenched by ferric ions via interacting with functional groups on the surface of N-CDs to form complex compounds. The normalized intensity versus the concentration of ferric ions showed a good linear relationship under the concentration in the range of 5-60 μmol·L-1. The detection limit of ferric ions was estimated to be 1.01 μmol·L-1. These results suggested that the as-synthesized N-CDs could be used as an effective fluorescent sensing platform for ferric ions in water.关键词：garbon dot;nitrogen-doped;fluorescent probe;ferric ion232|276|7更新时间：2020-08-12
- 摘要：Microcrystalline powders of YNbO4 with different Dy3+ doping concentration were synthesized by the conventional solid-state reaction at 1 300℃ and duration of 2 h. Their X-ray diffraction patterns were examined and the results confirmed the formation of single phase crystalline structure of YNbO4. Their absorption spectra were measured through combination of a scattering integral sphere and a fiber spectrometer, and in consequence, spectrum intensity parameters(Ω2, Ω4 and Ω6), experimental and theoretical oscillator intensities of YNbO4:Dy3+ were calculated through Judd-Ofelt theory. Excitation spectra with emission peak at 577 nm were recorded and the results illustrated that there were an excitation peak near 260 nm due to absorption of crystalline lattice of YNbO4 and several excitation peaks originated from 4f-4f transition of Dy3+ ions. Emission spectra excited at 270 nm and 360 nm were also measured and basically identical emission spectra were observed. Concentration quenching phenomenon of Dy3+ ion's luminescence was discovered by comparing emission spectrum of different Dy3+ doping concentration. Analytic results according to energy transfer theory indicated that concentration quenching mechanism in Dy3+ ions belonged to dipole-dipole interaction. At last, CIE color coordinates of the prepared samples were also calculated and color parameters with nearest distance to white light region were (0.219, 0.166).关键词：YNbO4;Judd-Ofelt theory;CIE coordinate;dipole-dipole interaction147|87|0更新时间：2020-08-12
Synthesis and Properties of Materials
- 摘要：In this paper, a two-step solution method including dimethyl sulfoxide(DMSO) as additive is used to prepare a high-quality CH3NH3PbI3 absorb layer for carbon-based hole conductor-free perovskite solar cells(PSCs), which have the structure consisting of FTO glass/compact TiO2/mesoporous TiO2/CH3NH3PbI3/carbon electrodes. The effects of dipping time and dipping concentration on the photovoltaic performance of PSCs are studied. Introducing some DMSO in the PbI2/DMF solutions results in formation of porous and loose PbI2 films, which shortens the time required for the complete conversion of PbI2 to perovskite. When the dipping time is 40 min, the PSCs have the best photovoltaic performance with the open circuit voltage of 0.82 V, the short-circuit current density of 21.21 mA/cm2, the fill factor of 0.49, and the photoelectric conversion efficiency of 8.61%. However, when the dipping time is too long, the large grains will appear on the surface of the CH3NH3PbI3 absorb layer, resulting in the poor photovoltaic performance of PSCs. In addition, the concentration of MAI/IPA solution will significantly affect the rate of the conversion of PbI2 to CH3NH3PbI3. The higher the concentration of MAI/IPA solution is, the faster the rate of the conversion of PbI2 to CH3NH3PbI3 is.关键词：perovskite solar cell;two-step solution method;dipping time;dipping concentration;photovoltaic performance195|179|0更新时间：2020-08-12
- 摘要：In order to improve the interfacial properties of organic semiconductor devices, polymethyl methacrylate(PMMA) was spin-coated on the silicon nitride insulation layers to fabricate a compound insulation layers. First, the surface topography and roughness of composite insulation layers with different PMMA concentration were investigated by atomic force microscope. Then, the organic metal-insulation-semiconductor(MIS) devices were fabricated by vacuum evaporating of para-hexaphenyl(p-6P), phthalocyanine copper and the gold material electrodes, respectively. Finally, the hysteresis effect and electrical properties of MIS devices were studied. The experimental results show that the roughness of the compound insulation layers was lower than 1/5 of the single insulating layers and was about 1.4 nm. The p-6P films can form the larger and more ordered domains on the compound insulation layers with the increase of PMMA concentration, but it is formed spherical islands on the single insulating layers. The organic MIS devices of the compound insulation layers have almost no hysteresis, but the devices of single insulation layers have the largest hysteresis voltage of about 12.8 V and its internal trap charge density is about 1.16×1012 cm-2. The mobility of MIS devices with the compound insulation layers is 1.22×10-2 cm2/(V·s), which is 60% higher than that of MIS devices of the single insulation layers. The saturation currents are increased by 345%. The MIS devices based on the compound insulation layers have better interface performance and electrical performance which can be applied to the field of organic display.关键词：compound insulation layers;metal-insulator-semiconductor;polymethyl methacrylate;silicon nitride;hysteresis effect171|139|1更新时间：2020-08-12
- 摘要：In order to study the orientation effects and the comprehensive heat dissipation performance of the high power radiator heat sink with the phase-change heat transfer in capillary microgrooves heat sinks, the experiment studies the variation of height, power and whether using the phase-change heat transfer in capillary microgrooves heat sinks on excess temperature and the mean convection heat transfer coefficient with the installation angles. And the correlations between the Ra and Nu are obtained. The results show that when the installation angle is less than 90 degrees, the excess temperature of heat source for microgrooves heat sinks is much lower than that of the section heat sink. When the installation angle is 30 degrees, the height is 90 mm, the input power is 80, 100, 120, 200 W, the heat source excess temperature 11.6, 13.3, 18.9, 26.7 K are reduced respectively, and the greater the input power, the greater the reduction. When the installation angle is greater than 90 degrees, the excess temperature of the microgrooves heat sinks is slightly higher than that of the section heat sink, and the reason is that the vacuum environment inside the microgrooves heat sinks affects the temperature uniformity, the higher the input power, the more obvious the orientation effects. The lower the height is, the greater the mean convection heat transfer coefficient is. When the installation angle is 0°, the input power is 80, 100, 120 W, compared with height 60 mm and height 90 mm, the mean convection heat transfer coefficient increased by 27.5%, 23.8% and 24.2%. Therefore, the orientation effects of the radiator should be considered when designing the radiator for LED lamps.关键词：high power LED;orientation effects;microgrooves;natural convection;radiator155|278|0更新时间：2020-08-12
- 摘要：In order to explore characteristics of CCD detector, according to the structural characteristics of CCD detectors, we developed a six-layer-structure, thermal-coupling, mathematical physical 3D model of a CCD detector that was irradiated by a 1.06 μm continuous laser. By changing the way of laser irradiating the CCD at different damage stages, the multi-layer damage mechanism of CCD detector was analyzed numerically and the time threshold was obtained. By comparison, the results demonstrated that due to melting the damage started from the microlens layer when the microlens focusing laser to photosensitive layer, causing the point damage of CCD. Then the aluminum film was fused and peeled by heat and stress after the microlens lost the ability to focus the beam, causing the vertical bright linear damage. With the molten Al film peeling off, the silicon electrode was irradiated directly and its surface was molted. Then the damaged wiring circuit made charges untransferable, causing the horizontal dark linear damage. Subsequently, the SiO2 insulating layer was torn up by shear stress, which made the molten silicon electrode in the upper and the silicon substrate in the lower conduct together, causing the complete damage of CCD. Additionally, the experimental and simulation results show the same trend with small error and verify each other.关键词：continuous laser;charge-coupled device;damage mechanism;damage time142|300|1更新时间：2020-08-12
Device Fabrication and Physics
- 摘要：The reliability analysis of multi-chip LED light sources involves multiple physical fields of light, electricity and heat. The high-precision analysis results will lead to too many calculation resources, too long calculation time and difficult calculation. To solve the above problems, the traditional finite element method(FEM) and efficient artificial neural network(ANN) method are used to analyze the temperature of LED light source, and the advantages and disadvantages of both are discussed. Finally, by combining the advantages of FEM analysis in a single heat transfer physics field with the advantages of ANN in little calculation time and low computational resource requirements, a more efficient method for heat dissipation analysis of multi-chip LED light sources is summarized. Using this method, the correlation coefficient between the prediction data and the training data of ANN reaches 0.997 79, and the prediction result has a good match with the actual heat distribution. The computational resource saves 59% compared with the traditional FEM method. The application of this method can consume fewer computing resources and time based on satisfying the accuracy, while improving the flexibility of analysis. In addition, this method has certain reference value for solving the reliability problems such as the lifetime of high-power LED light source.关键词：multi-chip LED light source;multiphysics field coupling;thermal analysis;finite element method;artificial neural network173|185|1更新时间：2020-08-12
- 摘要：Based on the experiment of influence of laser energy fluctuation on output electric pulse fluctuation, the influence of laser energy fluctuation on the jitter time of GaAs photoconductive switch was investigated theoretically. In the experiment, GaAs photoconductive switch was triggered using the wavelength of 1 053 nm and the pulse width of 500 ps laser pulse under the condition of 2 kV bias voltage. The influence of laser energy fluctuation on the output electrical pulse fluctuation was investigated. It is shown that the fluctuation of the laser energy is proportional to the output electrical pulse fluctuation through the contrast analysis. At the same time, it is pointed out that the jitter time of GaAs photoconductive switch increases with the increase of laser energy fluctuation through the analysis of the carrier transport. The fluctuation of energy does not cause the rapid change of switching jitter time with the increase of laser power fluctuation. GaAs photoconductive switch will also increase the zone of timing jitter until the energy reaches GaAs saturated absorption limit.关键词：GaAs photoconductive switch;jitter time;energy fluctuation155|121|0更新时间：2020-08-12
- 摘要：In view of the poor light transmission of thick skin fruit and the independent modeling of the sugar content of different grapefruit varieties, the grapefruit was the research object, and 325 effective spectra were collected to compare and analyze the spectral responses of two absorption peaks of different grapefruit varieties near 710 nm and 800 nm. In the 550-970 nm full-band spectrum, the false positive rate of the grapefruit partial least squares discriminant model is 1.25% after SPA no information elimination; the partial least squares method is in the 550-970 nm full-band range and the de-differential 750-930 nm band. The prediction correlation coefficients of the range are 0.58 and 0.86, respectively, and the predicted root mean square error RMSEP is 0.84 and 0.55, respectively. Experiments show that the continuous projection method combined with the partial least squares discriminant model can realize the qualitative discrimination of different grapefruit varieties. The coefficient of variation method is the best to quantify the soluble solids of the thick fruit grapefruit with the least squares model. This study provides a reference and theoretical basis for the online sorting technology of different varieties of thick fruit.关键词：near-infrared spectroscopy;on-line detection;universal model;soluble solids;variety discrimination139|360|4更新时间：2020-08-12
- 摘要：Damage effects and thermal evolution characteristics induced by space high-energy particles to spacecraft electronic devices are directly related to the safe operation of spacecraft and on-orbit tasks. In this paper, self-constructed femtosecond pulsed laser irradiation system, laser induced damage effect data acquisition system, data write-read system and infrared thermal imaging system were used to carry out different laser output frequencies and different areas of irradiated ferromagnetic random access memory(FRAM). Under the conditions, experiments were carried out to obtain the steady-state temperature field of the irradiated surface of the FRAM and the time of transient failure and permanent failure of the FRAM, and damage effect and thermal evolution on the FRAM were observed. The data were processed by MATLAB software. The temperature distribution of the thermal evolution process in different areas of the laser irradiated FRAM was obtained. The results show that the laser pulse output power is approximately the same under the conditions of femtosecond pulsed laser irradiation, the lower the laser pulse output frequency, the longer the moment of permanent damage induced, the longer the nonlinear growth; with the laser output frequency increasing, the effect of the laser on the FRAM, induced by the high-energy charged particles generated by the laser ionization memory medium mainly destroys the spontaneous polarization of the ferroelectrics, and gradually transforms into the damage induced by thermal radiation and thermal stress. When the maximum temperature produced by the laser on the surface of the device is close to the highest working temperature of the memory, the time of permanent damage will be significantly prolonged. Through the calculation of the regression parameters and the hypothesis test, the fitting relationship between the maximum radiation temperature and the laser output frequency of laser irradiation area 1 and area 2 is given, under the condition that the confidence degree 1-α is 95%.关键词：femtosecond pulsed laser;damage effect;ferromagnetic random access memory (FRAM);temperature field distribution179|272|1更新时间：2020-08-12
Luminescence Applications and Interdisciplinary Fields
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