最新刊期
卷 39 ， 期 3 ， 2018
- 摘要：KBaGd(MoO4)3:Dy3+ phosphors were synthesized by sol-gel method, and their morphology, structure and spectral properties were investigated by means of SEM, XRD, excitation and luminescent spectra, as well as luminescent decay curves. The results show that the shape and the particle size distribution of samples synthesized by sol-gel method are more regular and narrower than those synthesized by solid state method. Under the excitation of near UV light (390 nm), the samples exhibit two intensive emission bands around 485 nm and 577 nm, and the value of B/Y is about 0.7. In the host of KBaGd(MoO4)3, the optimum mole fraction of Dy3+ is 10%, and the concentration quenching effect is caused by dipole-dipole interactions between Dy3+ ions. The luminescent lifetime becomes shorter and the decay curves become nonexponential with the increasing of Dy3+ concentration.关键词：molybdate;phosphors;concentration quenching;color coordinate173|129|1更新时间：2020-08-12
- 摘要：Er3+/Yb3+ co-doped TeO2-ZnO-Bi2O3 tellurite glasses were first prepared by melt-quenching method. Through precipitation of Zn2Te3O8 micro-crystals by heat treatment and introduction of Ag nanocrystals respectively, the luminescence properties of glasses are improved. However, after further heat treatment, the luminescence properties of glasses with Ag nanocrystals decrease. As Ag nanocrystals can lead to excessive crystallization of glasses during heat treatment process, the auxiliary electric field heat treatment method is applied to control the precipitation of Ag nanocrystals and micro-crystals. After auxiliary electric field heat treatment, more Ag nanocrystals are produced and the growth of micro-crystals is controlled, which lead to the improved luminescence properties of glasses.关键词：tellurite glasses;micro crystallization;Ag nanocrystals;auxiliary electric field102|82|0更新时间：2020-08-12
- 摘要：A series of phosphors CaY1-xAlO4:xRE3+(RE=Dy, Ho, Sm, Tm) were synthesized by sol-gel method. X-ray powder diffraction (XRD), high resolution transmission electron microscopy (TEM) and fluorescence spectrophotometer were utilized to characterize the samples on phase structure, morphology and fluorescence properties,respectively.The results show that the synthesized samples are nanometer material with tetragonal crystal structure.Under UV light excitation, the doped rare earth ions exhibit f-f feature level transitions. The doped ions give the strongest emission when the doped mole fraction (x) of Dy3+, Ho3+, Sm3+ and Tm3+ is 0.03, 0.015, 0.015 and 0.02, and give white, green, orange and blue emission, respectively.关键词：sol-gel method;CaYAlO4:Dy3+;Ho3+;Sm3+;Tm3+;luminescent properties139|159|0更新时间：2020-08-12
- 摘要：Using seed-growth method, gold nanostars and gold nanobipyramids were synthesized, respectively, and they were characterized by transmission electron microscope and ultraviolet-visible (UV-Vis) spectrophotometer. Moreover, the photothermal conversion, biocompatibility and in vitro photothermal therapy (PTT) of gold nanostars and gold nanobipyramids were evaluated. The results show that the UV-Vis absorption peaks of gold nanostars and gold nanobipyramids are located at about 808 nm and 815 nm, and the photothermal conversion efficiency is calculated to be 48.43% and 53.68%. The cell experiments indicate that the gold nanostars and gold nanobipyramids have good biocompatibility, and the viabilities of MCF-7 cells incubate with gold nanostars and gold nanobipyramids are decreased to be about 22.54% and 13.73%, after they are irradiated by 808 nm laser for 5 min, respectively. Furthermore, compared with the gold nanostars, the gold nanobipyramids have more excellent PTT performance, which could be good candidate as safe and high-efficient nanoprobe material for PTT in tumors.关键词：gold nanostars;gold nanobipyramids;photothermal therapy220|452|2更新时间：2020-08-12
- 摘要：Long afterglow phosphors SrLaGa3O7:xSm3+ were prepared by solid state reaction. The crystal structure and luminescent properties of the samples were studied via XRD, photoluminescent (PL) and thermoluminescent (ThL) spectra. Furthermore, the effect of doping Sm3+ on long afterglow properties of SrLaGa3O7:xSm3+ was detailedly investigated. The obtained results show that SrLaGa3O7 exhibites long afterglow emission located at 386 nm after the excitation of 254 nm UV light, which can persist more than 60 min. The existence of vacancies in SrLaGa3O7 is responsible for the long afterglow emission. Following the increase of doping Sm3+ content, the luminescent and afterglow intensity increases and arrives at the strongest values and then decreases. In addition, the luminescent and afterglow emission wavelength shifts towards longer wavelength. When the doping Sm3+ mole fraction reaches 0.5%, SrLaGa3O7 possesses the best long afterglow properties. The thermoluminescence spectra results indicate that the doping Sm3+ can result in two different traps, which are created by VO¨ and V″Sr vacancies. These traps affect not only the PL intensities but also the afterglow properties.关键词：SrLaGa3O7:Sm3+;long afterglow properties;photoluminescence;thermoluminescence;traps142|231|1更新时间：2020-08-12
- 摘要：In order to study the performance of Li-N dual-doped ZnO thin film prepared by electron beam annealing technology, the Li-N dual-doped ZnO precursor films were prepared by sol-gel spinning method and annealed by electron beam. The accelerating voltage, focus beam current and annealing duration were fixed at 10 kV, 123 mA and 5 min, respectively. The electron beam current was within the range from 0.7 mA to 1.9 mA. Finally, the Li-N dual-doped ZnO films were obtained. When the electron beam current is more than 1.5 mA, the result of X-ray diffraction shows that the samples are a compound polycrystalline films of hexagonal ZnO and cubic ZnO, and the metal Zn generates in the films which contributes to the green light emission. SEM pictures show that the grain size increases with the electron beam current. There is not much change in grain size when the electron beam current is more than 1.5 mA and it is about 60 nm. The analysis of photoluminescence (PL) and Raman spectra show that Li and N have doped in the ZnO lattice. The doped Li contributes to the purple light emission in the PL spectra and the vibration mode related to the doped N replacing O is observed in Raman scattering spectra.关键词：electron beam annealing;doping;polycrystalline;ZnO thin film182|148|0更新时间：2020-08-12
- 摘要：The powders of Ho,Yb:(LaLu)2O3 were prepared by citric acid combustion method. The preparation conditions of the powders were determined. The as-prepared particles are of near-spherical shape, and weak agglomeration, the average particle size was about 55 nm. The effects of different mole fraction Ho3+ and Yb3+ on the fluorescence spectra of the powders were studied. Under the excitation of 980 nm, the powders can emit blue-ray appeared at 484 nm, corresponding to the energy level transition of Ho3+ from 5F3 to 5I8, green light appeared at 551 nm, corresponding to the energy level transition of Ho3+ from 5S2/5F4 to 5I8, and red light at 660 nm, corresponding to the energy level transition of Ho3+ from 5F5 to 5I8. The upconversion luminescence mechanism of Ho3+-Yb3+ in co-doped system was discussed.关键词：holmium ytterbium co-doped lanthanum lutetium oxide;upcoversion spectrum;energy transfer137|168|0更新时间：2020-08-12
- 摘要：Lu2O3:xPr3+ and Lu2O3:0.1%Pr3+,yM (M=Li+, Na+, K+, Ca2+, Ba2+) phosphors were synthesized by the high temperature solid-state reaction. The structures of the samples were characterized by XRD, the excitation spectra, emission spectra and luminescence decay curves of the samples were measured. The influences of the doping metal ions of Li+, Na+, K+, Ca2+ and Ba2+ on the microstructure, luminescence intensity and fluorescence lifetime for synthesized samples of Lu2O3:Pr3+ were researched. The results show that the samples after doping metal ions are still pure Lu2O3 cubic crystal phase structure. The emission intensities of Lu2O3:0.1%Pr3+ samples doped with 12%Li+, 8%Na+ and 8%K+ increased 7.32, 4.11 and 2.55 times than that of Lu2O3:0.1%Pr3+ sample, but the emission intensities of samples doped with Ca2+ and Ba2+ decreased. Compared with 1D2 fluorescence lifetime of Lu2O3:0.1%Pr3+ sample, the lifetime of the samples codoped with Li+, Na+, K+, Ca2+, Ba2+ all decreased.关键词：phosphor;Lu2O3:Pr3+ codoped with the metal ions;luminous intensity;fluorescence lifetime146|55|6更新时间：2020-08-12
- 摘要：For the purpose of improving the performance of organic light-emitting device (OLED), the green phosphorescent OLED was fabricated using Ir(ppy)3 as emitter and CsN3 as N-dopant doped in B3PYPPM which functioned as electron-transporting layer (ETL). The N-doped device with best performance named device B comprising ITO/HAT-CN(5 nm)/TAPC(70 nm)/TCTA:Ir(ppy)3(15%, 20 nm)/B3PYPPM(17 nm)/B3PYPPM:CsN3(10%, 63 nm)/Al was achieved by optimizing the doping concentration and the thickness of N-doped ETL. The results indicate that employing the N-doped ETL possessing proper doping concentration as well as thickness can enhance current efficiency and power efficiency dramatically. Served effectively as N-dopant in B3PYPPM, CsN3 reduces the injection barrier for electron, enhances the electron conductivity, facilitates the electron injection and transportation and enhances the charge balance, leading to the decrease in turn on and operating voltages as well as improvement on current efficiency and power efficiency. The optimized N-doped device B shows rather low turn-on voltage with the value of 2.1 V, and the maximum efficiencies are 67.0 cd/A and 91.1 lm/W respectively. It is worthwhile to point out power efficiency of device B can also reach 80.1 lm/W at high luminance of 1 000 cd/m2.关键词：CsN3;B3PYPPM;N-dopant;current efficiency;power efficiency114|182|4更新时间：2020-08-12
- 摘要：The inorganic oxide MoO3 thin films were prepared by thermal evaporation deposition method, and used as an anode buffer layer for PHJ perovskite solar cells. The results show that the MoO3 anode buffer layer can enhance the hole extraction efficiency from the light absorption layer to the anode, and benefit the improvement of the short-circuit current (Jsc) density and the fill factor (FF) of the solar cells. An average power conversion efficiency (PCE) of 9.96% is achieved finally for the solar cells with a MoO3 anode buffer layer. In addition, the results also show that the MoO3 anode buffer layer can hinder the corrosion of ITO by acidic PEDOT:PSS and improve the stability of the solar cells.关键词：perovskite solar cells;anode interface modification;MoO3;inorganic oxide202|200|3更新时间：2020-08-12
- 摘要：To investigate the influence of interface charge on the performance of organic photovoltaic cells (OPVs), the single/double acceptor based planar heterojunction (PHJ) OPV based on P3HT donor were fabricated. Firstly, the effect of poly (3-hexylthiophene) (P3HT) film thickness, P3HT solvent, and the drying time of P3HT film on device performance was studied. To further improve the P3HT/SubPc PHJ performance, the cascade structure of ITO/PEDOT:PSS/P3HT/chloroboron (Ⅲ) subnaphthalocyanine (SubNc)/boron subphthalocyanine chloride (SubPc)/BCP/Al including double acceptors was fabricated, and the influence of SubNc thickness was also investigated. In the single acceptor system, by using the mixed solvent (V(chloroform):V(ODCB)=1:1) and drying in air for 10 min, the obtained P3HT film achieves the highest performance. While in the cascade structure, the power conversion efficiency (PCE) firstly rises then declines with the increase of SubNc thickness. When the SubNc thickness is 5 nm, the PCE is the highest. The photovoltaic parameters of cascade cell are all improved compared with the single acceptor based cells. Finally, to get insight into the physical mechanism between the interface charge and device performance, the effect of SubNc thickness on the dielectric characteristic of cascade cells was studied.关键词：organic photovoltaic cells;P3HT;device performance;dielectric property138|542|0更新时间：2020-08-12
- 摘要：In order to develop a wavelengths ultiplexing fiber-coupled module of high output power and high power denisty on the basis of single emitter semiconductor laser diode, and design a kind of new pump laser for fiber laser, a new-type fiber-coupled module composed of 30 LDs was designed based on ZEMAX optical design software, which can output three kinds of wavelengths. After collimation by micro lens, including FACs and SACs, spatial multiplexing, wavelength multiplexing, diversion by special mirrors, focusing by focus lens and coupling to a fiber, the module can produce above 357.91 W output power from a standard fiber with core diameter of 105 μm and numerical aperture (NA) of 0.22. The total fiber coupling efficiency is about 99.42%, and the power density is 27.24 MW/cm2. To test the practical feasibility of the module, analyzed the influence from the angle between the incident beam and the normals of optical fiber end face on the coupling efficiency, the results showed the effects from the angle is so tiny that can be neglected. At the same time, the application of ANSYS software for the thermal analysis of this module shows that the cooling performance of the module is pretty good. Therefore this module's performance is positive and of high reliability, which can meet the demand of single emitter semiconductor laser fiber-coupled module which is of high power, high brightness and multiple wavelengths. Additionally, this design is of great guiding significance for practical production.关键词：semiconductor laser;fiber coupling;multiplexing technology;ZEMAX209|224|4更新时间：2020-08-12
- 摘要：In order to detect the packaging induced stress of semiconductor lasers quickly and effectively, an experimental device which can reveal the encapsulation stress by detecting the polarization degree of each unit of laser bar was designed. The parameters of the semiconductor laser bar were experimentally tested and the finite element software was used to simulate the relationship between the degree of polarization and the packaging induced stress through the theory of the semiconductor energy band and stress. The experiment results show that the individual light-emitting unit of the bar is less polarized, the higher threshold current is due to the larger packaging stress. Through the calculation, the packing stress is 141.92 MPa, and the polarization equivalent stress is 26.73 MPa. The degree of polarization of the device below the threshold reflects the distribution trend of the packaging induced stress, and the degree of polarization of the device can be measured by using the following threshold current. It can provide a quicker and more efficient method for selecting the heat sink and the solder material and the improvement of the welding process parameters.关键词：laser bar;polarization;packaging induced stress;polarization equivalent stress155|446|1更新时间：2020-08-12
- 摘要：A micro-gap dielectric barrier discharge decive in a parallel plate geometry is excited by a saw-tooth voltage to produce a stepped discharge, whose current waveform presents a plateau every half voltage cycle. It is found that the duration and amplitude of the discharge plateau increase with the increasing of the peak value of the applied saw-tooth voltage. The temporal evolution in the discharge plateau is investigated through optical method. It is confirmed that the stepped discharge is in an atmospheric Townsend discharge regime. Scanning the optical emission spectrum from the discharge, it is found that the spectrum is composed of the second positive system of nitrogen molecule(C3Πu→B3Πu), OH(A2∑+→X2Π) and Ar Ⅰ. With the increasing of the peak value of the applied saw-tooth voltage, it increases for the spectral intensity of OH (308.8 nm) and the molecular vibrational temperature, while the excited electron temperature decreases. By comparing the spectral line intensity of Ar Ⅰ(750.4 nm), it is found that the spectral line intensity produced by saw-tooth wave excited dielectric barrier discharge is larger than that of sine wave excited dielectric barrier discharge under the same peak voltage. All of these physical phenomena mentioned above are analyzed qualitatively by gas discharge mechanism.关键词：optical emission spectrum;temporal evolution;dielectric barrier discharge;townsend discharge;molecular vibtration tempearture;electron excited temperature119|162|0更新时间：2020-08-12
- 摘要：The memory devices based on composites of PS and PC61BM were investigated. By adjusting the buffer layer materials, we optimized the ON/OFF current radio of the device. With Au-NPs, PEDOT:PSS, PVP as a buffer layer at the context layer of the active layer respectively, the adjustable ON/OFF current radio, different memory mechanism of electrical bistable device is obtained. The measurement results show that the buffer layer conductivity plays an important role in ON/OFF current radio. When the buffer layer material changed PVP to Au-NPs, the ON/OFF current radio increased gradually from 102 to 105. In addition to the memory mechanism of different structure, through the I-V fitting curve and energy band diagram analysis, it is found that the conductive properties and energy level of buffer material are important factors of affecting the memory mechanism.关键词：organic;electrical bistable;memory device;buffer layer126|191|0更新时间：2020-08-12
- 摘要：To meet the requirement of high responsivity of silicon-based photodetector in visible light communication (VLC), a novel silicon-based metal-semiconductor-metal photodetector utilizing the abnormal optical transmission of subwavelength metal grating was proposed. The effects of grating height, grating period and slit width on the absorptive performance of the photodetector were analyzed in detail by using the method of finite difference time domain. The simulation results indicate that the absorption enhancement was improved by the Fabry-Perot resonance and the surface plasmon polariton. For the VLC system with a wavelength of 615 nm, the optimum period, the optimum height and the optimum slit width of the metal grating are 580, 91, 360 nm, respectively. The absorption efficiency of the designed detector was 32% higher than that of the detector without metal grating. Since the proposed photodetector is based on standard CMOS process, it has potential application in the visible light communication.关键词：visible light communication;photodetector;subwavelength metal grating;absorption;Fabry-Perot-like resonance;surface plasmon polariton166|321|4更新时间：2020-08-12
- 摘要：ZnO nanorods (NRs) were successfully fabricated on ITO substrates by hydrothermal method, and UV detector of ZnO NRs was prepared with ITO as electrode. The UV properties of the devices were tested at room temperature. The results confirm that the ZnO NRs have an excellent response to UV light and the sensitivity of ZnO NRs UV detectors can reach 1 500 closing to 0 V. In addition, it can be seen that the ZnO NRs UV detector has good repeatability and stability in the cycle test.关键词：ZnO nanorods;hydrothermal;UV detector154|192|2更新时间：2020-08-12
- 摘要：When the thickness of HfO2 film reaches nanometer level, its optical properties will change. The spectral ellipsometer can obtain the thickness and optical constant of the film at the same time. However, due to the relevance of the measurement parameters, the results of optical constants are not accurate and reliable. In this paper, the thickness of HfO2 film is accurately measured by the grazing incidence X-ray reflex technique which can be traced to SI units. Then, the thickness of the HfO2 film and the optical constant were measured by the spectral ellipsometer to obtain the accurate optical parameters of the film corresponding to the thickness of the film. The influence of the thickness of ultra-thin HfO2 films with the nominal thickness of 2, 5, 10 nm on the optical properties was studied, using Al2O3 as the film buffer layer. The experimental results show that the refractive index increases with the increase of HfO2 film thickness, but the refractive index is 1.901, 2.042, 2.121 at the laser wavelength, and is close to the bulk material, but the extinction coefficient is always zero. It is shown that the nanoscale HfO2 thin films have a good effect on the broad spectrum and it does not absorb light.关键词：nanoscale HfO2 thin films;grazing incidence X-ray reflectivity;spectroscopic ellipsometry;characterization of thickness and optical properties122|253|1更新时间：2020-08-12
- 摘要：The characteristics of TFT are critical to the reliability of metal oxide-TFT drived LCD. The effect of Vth and stability of oxide-TFT to the reliability of narrow-bezel LCD display were researched. The negative Vth of the normal-on oxide-TFT can result in the failure of VSR scan circuits. Others, the negative-shift of the Vth of TFT in pixel at high temperature and under back-light illumination can cause the Vth negative shift and results in the cross-talk or image-sticking because of the high leakage current of TFT.关键词：oxide TFT;threshold-voltage (Vth);LCD;reliability163|312|2更新时间：2020-08-12
- 摘要：Carbon quantum dots (CQDs) were prepared by hydrothermal treatment with cigarette filters as raw material. The results indicate that the fluorescence could be quenched by dopamine with high specificity. Based on this phenomenon, a fluorescence sensor was developed for the detection of dopamine in phosphate solutions (pH=8.0). Furthermore, the quenching mechanism of the CQDs was elucidated. The fluorescence quenching value showed linear responses with dopamine concentration ranging from 1.2 to 84.0 μmol/L with the detection limit of 0.80 μmol/L(3σ/k). Satisfactory results were achieved when the method was submitted to the determination of dopamine in real samples.关键词：carbon quantum dots;fluorescence quenching;detection;dopamine130|164|2更新时间：2020-08-12
- 摘要：Using hyperspectral techniques for kind discrimination of egg can provide scientific methods for non-destructive discrimination kind of egg. In this study, hyperspectral images of three kinds of egg samples were acquired in wavelength range from 400 nm to 1 000 nm by hyperspectral system, and pretreatment methods were used to process original spectrum. Then the characteristic wavelengths were selected from the pretreatmented spectral data by CARS, GAPLS and IRF. KNN and PLS-DA discriminant models of eggs were established based on full spectrum and characteristic wavelengths, respectively. The results show that the Detrend method is the optimal pretreatment method. And the number of the characteristic wavelengths selected by CARS, GAPLS and IRF are 31, 52 and 71, respectively. PLS-DA model based on characteristic wavelength extracted by IRF method is optimal, and accuracy of the calibration set and the forecast set are 97.02%, 85.71%, respectively. It is feasible to discriminate kind of egg based on hyperspectral reflectance imaging.关键词：visible/near infrared;hyperspectral imaging technology;egg;non-destructive discrimination;interval random frog163|452|7更新时间：2020-08-12
- 摘要：Traditional plant lamp's optical structure is easy with poor color uniformity and illumination uniformity. It is not good for plant growing. For this reason, a LED panel light with high color-mixed uniformity and illumination uniformity was designed. The design used a pyramidal optical element to divide the light emitted by the LED into transmission part, reflection part and direct part. This method can increase the light coupling, and improve the uniformity of the mixed light and color on light emitting surface. Furthermore, the illumination uniformity was used to instead of the photosynthetic photon flux density (PPFD) uniformity and conjuncted it with color-mixed uniformity as the examining index. Then, the Taguchi method was used to design and experiment, studying the influence of different factors on light uniformity. Finally, the results were obtained and optimized after the experimental. A plant light source with 92.13% illumination uniformity and 89.72% color-mixed uniformity was gotten.关键词：LED;plant factory;plant source;mixing uniformity;optical design178|132|9更新时间：2020-08-12
- 摘要：In machine vision, there are many problems exist in light-source, like long running times, manual debugging, heating seriously and poor adaptability. Accordingly, a digital dimming method of light source was proposed based on PWM technology, which was divided into eight situations. The limitation of this model was pointed out and the principals of the digital light-source was declared from three aspects:dimming theory, control theory as well as driving theory. In the meanwhile, four representative experiments were showed out. The results show that this method can satisfy most proportion of the mixed light models, and realize the adjustment of color as well as the change of illumination. With the function of trigger control, the above problems can be solved properly, at the same time, postponing aging of light-source and energy saving can be achieve as well.关键词：light source;machine vision;PWM;mixed light;LED139|398|1更新时间：2020-08-12
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