最新刊期
卷 40 ， 期 1 ， 2019
- 摘要：It remains a challenge for enhancing the limited upconversion efficiency of rare earth doped materials, which restricts their applications severely. In this paper, we synthesized alkali metal ions and rare earth ions co-doped fluorides using hydrothermal method, the upconversion properties were investigated as well. By comparing the upconversion spectra, effects of the doping alkali metal ions were discussed. It is found that doping Li+ can significantly enhance the upconversion intensity of rare earth doped NaYF4 nanocrystals, a nearly 7 times stronger emission was achieved in LiYF4 host than that in NaYF4. In addition, efficient white light emission was obtained in rare earth doped LiYF4 matrix (CIE coordinates, x=0.32, y=0.36), after optimizing the doping concentrations. This work provides references for fabricating the highly efficient upconversion materials, as well as the new generation lighting devices.关键词：impurities;alkali metal elements;upconversion efficiency;white light200|228|4更新时间：2020-08-12
- 摘要：Gd2SiO5:RE phosphors were prepared by high temperature solid-state method with Gd2O3 and SiO as the raw material. The effects of calcining temperature, Gd/Si atomic ratio and fluxing agent on the Gd2SiO5 crystallized power fabrication were studied systematically, by means of X-ray diffraction (XRD). The optimum calcining condition is holding at 1 500℃ for 3 h with Gd/Si atom ratio of 1.9, and BaF2 of 5‰ used as flux. Photoluminescent spectra show that the excitation rang is 250-470 nm for Gd2SiO5:Eu, while 250-320 nm for Gd2SiO5:Tb. The strongest peak in the emission spectra is 620 nm (related to Eu3+:5D0→7F2) for the former phosphor. For the later phosphor, the strongest peak locates at 548 nm (related to Tb3+:5D4→7F5). The best doping amount is 7% for Eu3+ and 5% Tb3+. The collaboration of fa(E) and fe(E) for Gd3+-Tb3+ is better than that of Gd3+-Eu3+, so the Gd2SiO5:xTb will have higher quantum yields than Gd2SiO5:xTb.关键词：gadolinium silicate;photoluminescent spectra;energy transfer;high temperature solid-state method131|201|0更新时间：2020-08-12
- 摘要：GaSb quantum dots were directly grown on (001) GaAs substrates by metal organic chemical vapor deposition. The effect of reaction chamber pressure on the size anisotropy of GaSb/GaAs quantum dots was analyzed. By the Sb surface treatment, a floating layer of Sb-Sb with low surface energy is formed on a GaAs substrate to achieve growth of GaSb quantum dots with an interfical misfit(IMF) growth mode. The morphologies of GaSb quantum dots were characterized by atomic force microscopy (AFM), and the results showed that the anisotropy of GaSb quantum dots is significant and elongated along the[110] direction. With the reaction pressure of 10 kPa, the aspect ratio of the asymmetric island caused by IMF growth mode is more than 3. Because of the low energy for (111) sidewalls, the GaSb quantum dots preferentially grow up along the[110] direction rather than the[110] direction. When eaction pressure is reduced to 4 kPa, the density of quantum dots increases to 8.3×109 cm-2. The shape of the quantum dots transforms into a symmetrical hemisphere and the aspect ratio is approximately 1. Because the low pressure reduces the activation energy of the atoms and increases the diffusion length, the anisotropy of GaSb quantum dots can be effectively improved.关键词：GaSb/GaAs quantum dots;anisotropy;IMF growth mode;MOCVD135|141|0更新时间：2020-08-12
- 摘要：The recently developed 3D GaN-based light emitting diodes (LEDs) can solve problems associated with typical GaN-based thin film LEDs including the quantum-confined Stark effect, efficiency droop, and monochromatic wavelength. To resolve these issues, the micro-pyramids were synthesized and their luminescence properties were subsequently studied. First, GaN micro-pyramids with a base size of 8 μm and height of 7.5 μm were successfully fabricated after SiNx was deposited in situ by MOCVD, followed by three deposition periods of InGaN/GaN multiple quantum wells on the semi-polar facet of the GaN micro-pyramids. The cathodoluminescence measurements showed that the wavelength of the emission peaks varied on the semi-polar facet of the GaN micro-pyramids. According to micro-photoluminescence measurements obtained using different excitation power densities, the polarization field on the semi-polar facets of the GaN micro-pyramids containing InGaN/GaN multiple quantum wells was rather weak. The atomic migration mechanism was determined from the cathodoluminescence and transmission electron microscopy results. The GaN micro-pyramids can possibly be used for fabricating LEDs with multi-color emission due to their unique structures and optical properties.关键词：GaN micro-pyramid;metal-organic chemical vapor deposition;optical materials;quantum dot191|193|0更新时间：2020-08-12
- 摘要：Yb3+, Er3+ co-doped up-conversion luminescent materials can be used to measure the internal temperature of tissue under infrared light excitation, but the lower efficiency of up-conversion materials makes it impossible to detect deep tissue temperature. Considering that Er3+ energy levels can be populated by various light sources, X-ray is undoubtedly an ideal excitation source with better penetration. In this article, we first reported a novel deep tissue temperature sensing material La2O2S:Yb3+,Er3+. The data show that the fluorescence intensity ratio of the two green levels at different temperatures conforms to Boltzmann distribution under X-ray excitation, and the maximum sensor sensitivity is 0.011 5 K-1. We believe that Yb3+, Er3+ co-doped La2O2S can be used as an ideal temperature measuring material for clinical application.关键词：Boltzmann distribution;tissue temperature detection;La2O2S:Yb3+;Er3+;fluorescence intensity ratio;sensor sensitivity210|180|2更新时间：2020-08-12
- 摘要：In order to study the photocatalytic effect of tungsten oxide(WO3) and silver/tungsten oxide(Ag/WO3) nanofibers. The WO3 and Ag/WO3 nanofibers were fabricated by electrospinning method. The crystal phase, morphology and ultraviolet-visible diffuse reflectance spectroscopy of the samples were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and UV-Vis spectrophotometer(UV-Vis). The photocatalytic degradation performance on Methyl Blue(MB) with WO3 and Ag/WO3 nanofibers was evaluated under UV-Vis light irradiation. The results demonstrate that the photocatalytic degradation efficiency on MB with Ag/WO3 nanofibers is 1.3 times higher than WO3 at 90 min. Based on the energy band structure, the principle of photocatalytic efficiency enhancement of Ag/WO3 composite fibers was analyzed.关键词：electrospinning;WO3 nanofibers;Ag/WO3 nanofibers;photocatalysis145|155|3更新时间：2020-08-12
- 摘要：A novel 10-(spiro[fluorene-9,9'-xanthen]-2-yl)-phenothiazine(SFXPz) with deep HOMO(the highest occupied molecular orbital)(-6.15 eV) and high triplet energy(T1, 2.82 eV) has been synthesized, which is expected to fabricate high-efficient blue phosphorescent organic light-emitting diodes(PhOLEDs) due to the importance of a wide energy gap(Eg, 4.33 eV) and deep enough HOMO in blue PhOLEDs. The good thermal stability(Td, 259℃) and high stable morphology(Tg, 206℃) of SFXPz were demonstrated by thermo gravimetric analysis(TGA) and differential scanning calorimetry(DSC) curves. The complete separation of HOMO and the lowest unoccupied molecular orbital(LUMO) of the compound is preferable to prevent the back of energy transfer. The UV-Vis spectrum peaks of SFXPz exhibit at around 230, 260, 292, 310 nm, respectively, and the corresponding fluorescence emission spectrum peaks show at about 311, 324 nm, respectively. In addition, the molecular structure is characterized detailedly by LC-MS, 1H NMR and 13C NMR, respectively.关键词：spiro[fluorene-9;9'-xanthene];phenothiazine;deep HOMO;structure-property relationships;steric hindrance161|128|1更新时间：2020-08-12
- 摘要：The spectra of odd-parity states of Eu atom are studied systematically with two-photon ionization detection technique. The two-photon ionization detection technique is utilized to obtain the spectra of odd-parity states with the two-step excitation:the wavelength of the first step laser is fixed, while that of the last-step laser is scanned around the region of 35 500-35 650 cm-1, 36 200-36 600 cm-1 and 46 650-46 950 cm-1, respectively. The characteristics of spectra in the energy region of 35 500-35 650 cm-1, 36 200-36 600 cm-1 and 46 650-46 950 cm-1 are investigated, demonstrating the special lifetime of highly excited states within those energy regions. In this paper, three different excitation pathways are used, not only the energy levels, line width and line shape are obtained, but also the q-reversal phenomenon is observed in the odd-parity states spectra. Besides, by analyzing the odd-parity states spectra of Eu atom, it is demonstrated that the possibility of 4f electrons are excited for the first time.关键词：Eu atom;two-photon ionization;4f electrons;q-reversal140|124|0更新时间：2020-08-12
Synthesis and Properties of Materials
- 摘要：The photoelectrochemical (PEC) process is a low-cost approach to convert chemical energy to electricity under light illumination. The photoelectrochemical biosensing has attracted huge attention because of its ability to detect biomolecules through the photocurrent generated from biomolecule oxidation. The photoelectrochemical biosensors have extensive application prospect in the immunodetection, biotechnology and other important fields for their characteristics of low cost, high sensitivity, high specificity, simple operation, low detection background signal and so on. In recent years, the research of the performance and detection methods of photoelectrochemical biosensors have been made many achievements. This paper mainly introduces the concept, basic principle, classification, application and prospect of the photoelectrochemical biosensors.关键词：photoelectrochemical (PEC);biosensor;immunodetection257|590|2更新时间：2020-08-12
- 摘要：A direct-lit LED jaundice phototherapy lamp is proposed, which could achieve uniform planar spectral distribution on the receiving surface(baby crib). Firstly, according to the order of the number of LED from less to more, the arrangement mode of four kinds of monochromatic LEDs in the same substrate is designed, which could form four kinds of same size light field with uniform illuminance distribution on the same out-lighting surface respectively, and further to achieve uniform planar spectral distribution on the out-lighting surface and even receiving surface. Secondly, the simulation of the direct-lit LED jaundice phototherapy lamp shows that it can achieve uniform planar spectrum distribution on the receiving surface certainly. Finally, placing the diffusion plate or brightness enhancement film on the out-lighting surface of the direct-lit LED jaundice phototherapy lamp respectively, two kinds of LED jaundice phototherapy lamp samples are produced and the corresponding experiments are carried out. Results show that:in comparison, the LED jaundice lamp samples placing the brightness enhancement film on the out-lighting surface can make the receiving surface receive more energy. However, on the 600 mm×300 mm receiving surface, two kinds of LED jaundice lamp samples, which the value of planar spectral distribution uniformity is over 99.9% and the value of illumination distribution uniformity is over 74%, all meet national safety standards of infant phototherapy equipment.关键词：optical design;LED jaundice lamps;direct-lit;LED arrangement;planar spectral distribution;illumination uniformity110|124|0更新时间：2020-08-12
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Design of Photoelectric Coupler Module with Optical Fiber Embedded in Flexible Printed Circuit Board
摘要：In order to improve the coupling efficiency between the laser beams and the fiber embedded in the optical fiber interconnection system of the flexible substrate, a detachable and efficient photoelectric coupling module was designed in this paper. First of all, the structure size of the coupling module was analyzed, and the energy flow change of the laser beam was simulated with Matlab software after passing through the 45° total reflection mirror. In addition, Zemax software was used to simulate the fiber coupling system and optimize the structure of the coupling system with the orthogonal descent method, in regard to the multi-mode optical fiber with a core diameter of 62.5 μm and a numerical aperture of 0.25. Furthermore, the vertical cavity surface emitting laser beams with a wavelength of 1 310 nm and an output power of 1 W were coupled into the fiber. The analysis results showed that the coupling efficiency was axially symmetrical with axial deviation and angular deviation. When the manufacture deviation was maximum, the coupling efficiency reached 79.37% and the coupling loss was 1.00 dB. Therefore, the module had a high position deviation, the highest coupling efficiency can reach up to 85.35% and the lowest coupling loss was 0.69 dB.关键词：optoelectronic interconnection;optical fiber coupling;ZEMAX;vertical cavity surface emitting laser;deviation analysis144|162|1更新时间：2020-08-12 - 摘要：CZTSSe thin films were fabricated by co-sputtering method followed by selenization. The effect of selenization temperature on CZTSSe thin films and its solar cell performance was studied. The structure, morphology, optoelectronic and solar cell performance were characterized by X-ray diffraction, Raman, Scanning electron microscope (SEM), ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy, Hall effect measurement and digital source meter, respectively. The crystallinity of CZTSSe thin films showed the best crystallinity when the selenization temperature was 580℃ and the film surface was uniform and dense. The resistivity and carrier concentration reached minimum and maximum values of 1.57 Ω·cm and 8.2×1017 cm-3 respectively. The short-circuit current and conversion efficiency of the CZTSSe solar cells prepared at this temperature were up to 30.68 mA/cm2 and 5.17%, respectively. Compared with the solar cells selenized at 550℃ and 600℃, the conversion efficiency of CZTSSe solar cells selenized at 580℃ increased by 36% and 6% respectively. With increasing selenization temperature, the position of the (112) peak in XRD patterns and Raman peaks corresponding to A1 mode systematically shifted to lower diffraction angle and wavenumbers. Meanwhile, the band gap of the films decreased from 1.26 eV to 1.21 eV.关键词：CZTSSe;co-sputtering;selenization temperature;solar cell property128|289|1更新时间：2020-08-12
- 摘要：In order to analyze the luminescent characteristics and mechanism of perovskite materials, a stable perovskite light emitting diode was prepared. The transient current and transient electroluminescence of the device driven by electric pulsed are investigated. At a constant current density of 10 mA·cm-2, the luminance attenuated from the maximum to half in a duration of more than 30 min, which ensure the accuracy of the transient test. In the 0.1~20 ms pulse width, the luminous efficiency of the device increases with time, and there is a reverse current after power turn-off. In the pulse amplitude test, the brightness of low voltage easily reaches its saturation. In the offset voltage test, the intensity of electroluminescence at high offset voltage is lower than that at low offset voltage. Analyzing the transient test results, we can conclude that ion migration (MA+, Br-) leads to the bending of energy band in the interface of the perovskite layer, which weakens the carrier injection. Meanwhile, the exciton dissociation is suppressed, leading an increase in the electroluminescence efficiency.关键词：perovskite;transient electroluminescence;ion migration;band bending198|124|2更新时间：2020-08-12
- 摘要：Ceramic-embedded heat dissipation substrate was prepared employing AlN block embedded selectively into FR4 material. A comparison study on LED's optical characteristic was carried out between aforementioned substrate and regular MCPCB using LED-related test method. Ceramic-embedded heat dissipation substrate was used on a 30 W far and near integrated functional LED automobile lamp, with its light failure and reliability were investigated. It was found that the ceramic-embedded heat dissipation substrate was endowed with unparalleled heat dissipation performance in comparison with regular MCPCB and the FR4/AlN interface presented an excellent bonding strength, which could dramatically decrease the junction temperature of LED and improve LED's optical performance, thus enhancing the performance stability of LED automobile lamp.关键词：ceramic-embedded;heat dissipation;substrate;LED;automobile lamp;junction temperature;optical performance153|170|2更新时间：2020-08-12
Device Fabrication and Physics
- 摘要：The visible light indoor positioning system based on the received signal strength algorithm has a simple structure. However, due to diffuse reflection channels, system noise and other factors, the positioning accuracy is greatly limited. Therefore, this paper proposes to use artificial neural network to learn indoor visible light channel parameters, and to fit the real value of indoor channel parameters as well as achieve high-precision positioning. Firstly, the CDMA modulation technique is used to eliminate the problem of inter-symbol interference caused by visible multi-reference optical communications in the room. Then the CDMA despreading signal is normalized and input to an artificial neural network to train the coordinate function so as to fit the indoor visible light communication channel parameters. Finally, the spatial distance between the receiver and each LED reference point is estimated. Besides, because the neural network training data noise and the receiver signal noise will affect the positioning accuracy, the Newton-Raphson iterative method is used to further approximate the true coordinates of the test points. The experimental results show that in the 1 m×1 m×1.2 m indoor visible light communication positioning system model, the average positioning error of this system in the two-dimensional positioning application is 0.87 cm; in the three-dimensional positioning application, the average positioning error is 1.47 cm. In this paper, a visible light indoor positioning system based on received signal strength is proposed. This system uses CDMA modulation technology. The received signal is despreaded and input artificial neural network to estimate the channel parameters. To further reduce the positioning error caused by random processes such as noise, an iterative approximation algorithm for positioning-based coordinate solutions is proposed. The results show that the system can achieve high positioning accuracy in both two-dimensional positioning and three-dimensional positioning.关键词：visible light communication;indoor positioning;high precision;artificial neural network225|186|4更新时间：2020-08-12
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A Novel Near-infrared Fluorescence Aptasensor Assay for Ochratoxin A in Traditional Chinese Medicine
摘要：A novel near-infrared fluorescence aptasensor was developed using near-infrared fluorescence carbon quantum dots as probes, ochratoxin A(OTA) aptamers as specific binding OTA. The other mycotoxins were no interferences in the determination of OTA. The influence factors on the performance of the aptasensors were investigated including components of aptasensors, pH of the solution, incubation period. The optimum conditions were determined. Under the optimum conditions, a linear fluorescence signal response to OTA concentration was obtained over a wide OTA concentration range of 0.015-1.50 ng·mL-1 with a detection limit of 8 pg·mL-1. The proposed method was employed in the determination of trace OTA in forsythia suspense, radix puerariae, semen nelumbinis, malt, pericarpium citri reticulatae and radix liquiritiae successfully.关键词：near-infrared fluorescence;carbon quantum dots;aptasensor;traditional chinese medicine;ochratoxin A146|131|3更新时间：2020-08-12 - 摘要：Objective:To develop the performance evaluation protocol of automatic luminescence immunoassay analyzers. Methods:The principle, structure and operation of 30 different types of automatic luminescence immunoassay analyzers manufactured by 15 companies were investigated and tested to develop the performance evaluation protocol for sampling system:incubating system, cleaning system and optical system. Results:Incubating system:temperature control accuracy of all the instruments is (37±0.5)℃, and the fluctuation of temperature is not out of the range of 0.5℃. Sampling system:the range of sample injectors and reagent injectors varies greatly. The minimum volume of sample injectors is from 5 μL to 40 μL and the maximum volume is from 20 μL to 300 μL. The minimum volume of reagent jnjectors is from 5 μL to 50 μL and the maximum volume is from 47 μL to 450 μL. When the volume is > 10 μ L, most instruments can meet bias < 10% and CV < 3%. When the volume is > 50 μL, most instruments can meet bias < 5% and CV < 2%. The smaller the amount of sample is, the higher the requirement of instrument is, and the more difficult the technical realization is. A few instruments cannot meet the requirement of minimum injection amount of < 10 μL as claimed. Optical system:all the instruments can satisfy the claimed noise requirements. The linear range meets the clinical needs of more than 3 luminescence magnitudes, and some even reach 6 magnitudes. A few instruments go beyond bounds of precision (CV) 3% and stability (bias) 5%, which need further improvement. Cleaning system:some instruments'carry-over rate exceeds 10×10-6. Conclusion:The performance evaluation method of important modules of LIA is established. The applicability and practicability of the ptotocol are proved by testing.关键词：automatic luminescence immunoassay analyzer;system modules;performance evaluation protocol137|412|2更新时间：2020-08-12
- 摘要：There is less study for ordinary LCD display color gamut boundary calculation. In order to accurately and quickly acquire the gamut boundary of an ordinary LCD display screen, a novel calculation method which coupled iterative method and the inverse calculation model was proposed. The reverse characteristic calculation method is:first, the approximation input values of the known XYZ were calculated using GOG model, and then the input value RGB of known XYZ was calculated by successive approximation method, a positive characteristic model and the function between the main stimulus and primary input value were adopted during the process of successive approximation calculation. The calculation steps are:the initial value of iterative calculation is appointed firstly, then XYZ of color point which belongs to any elevation angle on any hue surface is calculated by iterative computation. Then the device value RGB of the XYZ is calculated. Lastly, whether the color point located on the color gamut boundary is based on the values of RGB. Experimental results show that the new algorithm requires fewer samples and less computation time, and its calculation results can better meet the actual requirements than SMGBD. The results indicate that this method can well calculate color gamut boundary of ordinary LCD screen.关键词：ordinary LCD display screen;color gamut boundary;inverse calculation model130|115|2更新时间：2020-08-12
Luminescence Applications and Interdisciplinary Fields
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