最新刊期
卷 38 ， 期 11 ， 2017
- 摘要：We report the observation of upconversion luminescence from Sm2+ ions, which demonstrate that changeable valence lanthanides can served as the ions for optical frequency transformation. Upon the excitation of 980 nm diode laser, the doped Sm2+ ions in the hybrid material of BaFCl0.5Br0.5:1%Sm2+-CaF2:1%Yb3+ emit red upconversion fluorescence peaked at 631, 644, 665, 689, 704, 729 nm from the 5D0,1→7F0,1,2 transitions, respectively. By transient dynamic analysis, we attribute the excitation of Sm2+ ions to the cooperation energy transfer process:two excited Yb3+ ions simultaneously transfer their energy to one Sm2+ ion.关键词：cooperative energy transfer;Yb3+-dimer;Sm2+;upconversion luminescence143|141|3更新时间：2020-08-12
- 摘要：ZnO quantum dots (ZnO QDs) were fabricated by wet chemistry method. By varying the synthesis conditions (reaction time, reagent concentration ratio and reaction temperature), the size and luminescence properties of ZnO QDs can be effectively controlled. Transmission electron microscopy, UV-Vis absorption spectra and fluorescence spectra were employed to analyze the influence of preparation conditions on optical properties of the synthesized ZnO QDs, and a set of optimized synthesis condition was obtained for the following fabrication of white-LED device. The physical mechanism of the device electroluminescence (EL) was investigated via the measurements of current-voltage curves and EL spectra. The results show that stable ZnO QDs can be obtained at room temperature when the synthesis condition is set as:concentration ratio of Zn(OAc)2 to LiOH is 2:1 and reaction time is 3 h. Finally, a p-i-n type LED was constructed by employing p-GaN:Mg wafer and Al2O3 thin film respectively as hole injection layer and electron blocking layer, and a white EL emission under forward injection current of 5 mA was achieved, where the CIE is located at (0.28, 0.30) and the color temperature is calculated to be 9 424 K.关键词：ZnO QDs;yellow-green emission;wet chemistry method;ZnO QDs/Al2O3/p-GaN heterostructure;white-LED163|149|1更新时间：2020-08-12
- 摘要：The phosphors with general molecular formula A0.98Nb2O6:Eu0.02(A=Ca, Sr, Ba) were prepared by the high-temperature solid state reaction technique. X-ray diffraction (XRD) results reveal that the obtained products are pure phase. The luminescence properties of A0.98Nb2O6:Eu0.02(A=Ca, Sr, Ba) were investigated by photoluminescence spectra(PL) and diffuse reflection spectra(DRS). A0.98Nb2O6:Eu0.02(A=Ca, Sr, Ba) phosphors can exhibit the characteristic red emission of Eu3+, and PL intensities of A0.98Nb2O6:Eu0.02are in the order of CaNb2O6>SrNb2O6>BaNb2O6. The charge transfer transition(CT) and f-f transition absorption of Eu3 + can be observed in the excitation spectra. With the increase of the host cationic radius, the CT band shows large red shift from 270 to 330 nm.关键词：ANb2O6;phosphors;charge transfer band;Eu3+186|41|1更新时间：2020-08-12
- 摘要：Y4Zr3O12:Eu3+ phosphors were synthesized by the sol-gel method. The crystal structure, morphology and luminescence properties were investigated by XRD, TEM and luminescence spectroscopy. The effects of calcination temperature and Eu3+ concentration on the luminescence properties were also studied. These phosphors can be efficiently excited by 394 and 467 nm. The optimal calcination temperature and optimal Eu3+ mole fraction are 1 400℃ and 18%, respectively. The mechanism of concentration quenching is attributed to the electric dipole-dipole interaction.关键词：Y4Zr3O12:Eu3+ phosphor;sol-gel;concentration quenching125|155|1更新时间：2020-08-12
- 摘要：Fluorescent materials P(CS-g-CA)Ds were prepared by hydrothermal method using chitosan, citric acid, and N-(2-hydroxyethyl) ethylenediamine as raw materials. It was found that grafted citric acid could significantly increase the quantum yield of chitosan polymer carbon dots. The P(CS-g-CA)Ds were characterized by infrared spectroscopy, ultraviolet spectroscopy (UV), X-ray powder diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, thermal decomposition and photoluminescence spectra. The fluorescence performance tests at different pH values show that P(CS-g-CA)Ds have excellent stability in the pH range of 4-12. The application performance of P(CS-g-CA)Ds in rice paper was studied by testing the carbonyl index and the vinyl index of the paper before and after UV aging. The results demonstrate that P(CS-g-CA)Ds have good UV aging resistance performance.关键词：chitosan;citric acid;polymer carbon dots;UV aging142|163|4更新时间：2020-08-12
- 摘要：Sr1-xCaxSi2O2N2:Eu2+/Y3+ (x=0, 0.15, 0.3, 0.6, 0.75, 0.95) phosphors were prepared by a high temperature solid-state reaction method. The effect of Y3+ doping on the luminescence properties of the samples was studied. The results revealed that Y3+ ion doping may significantly improve the photoluminescence properties of MSi2O2N2:Eu2+(M=Ca, Sr) because the point defect result from the substitution of Y3+ ions for M2+ could inhibit the oxidization of Eu2+ to Eu3+. Besides, The Y3+ ion has smaller radius which could relax the expansion caused by the larger Eu2+ in CaSi2O2N2:Eu2+. The structure of Sr1-xCaxSi2O2N2:Eu2+/Y3+ can solve more Eu2+ ions at an equal distortion degree. With the increasing of x values in Sr1-xCaxSi2O2N2:Eu2+/Y3+, the luminescence intension ratio of Sr1-xCaxSi2O2N2:Eu2+/Y3+(B1-B6) to Sr1-xCaxSi2O2N2:Eu2+(A1-A6) raises (120%~180%).关键词：Sr1-xCaxSi2O2N2:Eu2+;luminescence;rare earths;Y3+ doping156|95|1更新时间：2020-08-12
- 摘要：Cesium lead bromine quantum dots were prepared by hot injection method. The obtained quantum dots are cubic structure and present well dispersed nanocubes with uniform length of about 10 nm, which can be stable for more than 2 months in the air. The cesium lead bromine quantum dots have a wide excitation spectrum and strong green emission. The fluorescence decay is fitted to the double exponential process. The quantum dots can form uniform thin films by drop or spin coating method, which has important prospects in solar cell, photoelectric detector, LED, and laser applications, etc.关键词：perovskite;quantum dots;semiconductor;luminescence properties;fluorescence lifetime285|1329|3更新时间：2020-08-12
- 摘要：Experimental spectra of the Eu 4f76p3/2nd(n=6, 7) autoionizing states were investigated by using the three-step isolated-core excitation technique, while the impact of laser polarization on the spectra was studied for the first time. A detailed interpretation to the complex spectra of the 4f76p3/2nd (n=6, 7) autoionizing states is fulfilled by reproducing their line shapes with a multi-peaked fitting process. The spectroscopic information of the autoionizing states, like the total angular momentum (J, is deduced by comparing their corresponding spectra obtained under different excitation paths.关键词：Eu atom;spectrum of autoionizing state;laser polarization;selection rules135|89|0更新时间：2020-08-12
- 摘要：The polycrystalline KLa(MoO4)2:Yb3+,Ho3+,Tm3+ phosphors were synthesized by the simple hydrothermal method. Under the excitation of 980 nm laser, KLa(MoO4)2:Yb3+,Ho3+,Tm3+ phosphors show bright white upconversion emission visible to the naked eyes, which composes of blue emission at~475 nm from Tm3+, green and red emission at~540 nm and~651 nm from Ho3+. The experiment results show that the coordinates of KLa(MoO4)2:Yb3+,Ho3+,Tm3+ in the commission international CIE chromaticity diagram can be controlled from cool to warm white color depending on the rate of Ho3+/Tm3+ concentrations.关键词：white-LED;upconversion;phosphor;rare earths125|136|3更新时间：2020-08-12
- 摘要：Europium has been widely used in inorganic luminescent materials because of its excellent optical properties. The luminescence properties of the activator ions are determined by their valence state and are affected by the crystal structure of the matrix. Eu2+and Eu3+ exhibit different optical properties, and it is possible to obtain a white light when two kinds of ion in a single matrix. In this review, research progress about luminescent properties of Eu3+-Eu2+ coexisting in aluminate, phosphate, silicate and borate has been described, which was paid more attention at the present stage. In addition, the reduction condition of Eu3+to Eu2+ and the mechanism have been summarized in this paper.关键词：luminescent materials;reduction of Eu3+;Eu3+-Eu2+ coexist275|130|1更新时间：2020-08-12
- 摘要：Black silicon is a new type of electronic material which can significantly improve the efficiency of photoelectric conversion device, and the micro-nano structure black silicon is a more efficient novel black silicon material than the ordinary black silicon materials. Preparation of a large area, good appearance characteristics and high surface cleanliness black silicon material is the premise for the preparation of efficient black silicon solar cells. Firstly, using the wet etching method, through the design appropriate reaction device and a good means of process control, the large area micro-nano structures black silicon was prepared by the pyramid silicon. Then, the key processing technologies were discussed. Experimental results show that the micro-nano structures black silicon prepared by this processing method has the characteristics of good appearance characteristics, high surface cleanliness and low surface reflectance. Effectively removing the surface silver deposits, the weighted average reflectivity of the black silicon is as low as 4.06% in the wavelength range of 300-1 100 nm. This preparation method is suitable for the preparation of large area efficient micro-nano structure black silicon, which has important application value in the field of high-efficient black silicon solar cells.关键词：pyramid structure;micro-nano structure;black silicon;solar cell125|199|0更新时间：2020-08-12
- 摘要：Flexible LEDs have attracted significant interest in recent years for lighting and display applications. We present a polydimethylsiloxane based phosphor film that is capable of high elasticity and flexibility while actively emitting light. It not only exhibits good thermal stability in a wide range of -50-230℃, but also retains the optical properties as raw phosphors. The prepared transparent PDMS thin film and the corresponding phosphor film enable complete flexibility and elasticity, the largest elongation is up to 400% and 275%, respectively. Besides, white LEDs were fabricated using prepared YAG-doped phosphor film, showing average Tc of 6 925 K, CRI of 71 and mean luminous efficiency of 115.7 lm/W. Furthermore, the proposed photoluminescent films in two colors and a flexible 3×3 LED array glowing with three colors were fabricated using thin elastic and transparent rubber and subjected to stretching, rolling and folding to demonstrate their promising use in flexible lighting and display applications.关键词：light-emitting diodes;flexible design;phosphor film;optical properties281|186|1更新时间：2020-08-12
- 摘要：An efficient one-step solution method was demonstrated to prepare CH3NH3PbI3 perovskite solar cells by adding pyridine to the precursor solution. The film morphology, crystallinity, and optical properties of CH3NH3PbI3 perovskite films were investigated by SEM, AFM, XRD, UV-Vis and PL. The results show that the perovskite film properties (coverage of perovskite films and surface morphology) can be manipulated by incorporating a small amount of pyridine. The adding of pyridine is helpful to obtain a smooth, continuous and dense morphology. With the optimized pyridine volume fraction of 1%, the power conversion efficiency of 7.33% with Jsc of 14.64 mA/cm2, Voc of 0.82 V, and FF of 0.61 is obtained for the planar device structure. By contrast, the power conversion efficiency of the device without pyridine is only 1.01%. However, the further increase of the content of pyridine can result in the decomposition of perovskite, because the pyridine can easily form complexes with perovskite and induce the perovskite dissociation.关键词：perovskite solar cell;additive;morphology;pyridine290|195|0更新时间：2020-08-12
- 摘要：InGaNAs/GaAs quantum-well (QW) with high In composition (>40%) which covered the optical fiber communication wavelength range of 1.3-1.55 π was grown on GaAs substrate by molecular beam epitaxy (MBE). The characteristics of N atom incorporation and growth properties for InGaNAs/GaAs QW were studied by photo luminescence (PL) spectra at room temperature. The results show that the increasing of N composition can result in a large number of non-radiative recombination centers. The mole fraction of N decreases sharply from 2% to 0.2% with the growth temperature increasing from 480℃ to 580℃. The change of In composition and As pressure cannot influence the incorporation of N atoms and the adhesion coefficient of N is about 1. The PL intensity at 1.3 π for InGaNAs/GaAs QW is strongest at the growth temperature of 410℃ and Ⅴ/Ⅲ ratio of~25. Higher growth rate can obtain shorter surface migration length and improve the crystal quality.关键词：InGaNAs;quantum well;molecular beam epitaxy;photoluminescence140|257|0更新时间：2020-08-12
- 摘要：Vertical-cavity surface-emitting lasers (VCSELs) have already become the first choice of light sources for short-reach optical interconnects. As the continues growth of optical interconnects used for data center, there is an urgent need for high-speed VCSEL devices which can support high data bandwidth requirement. This paper performs a comparative thermal analysis of 980 nm VCSELs based on the finite element method. Parameters which can influence the active region temperature are studied in this work including bias current, oxide aperture diameters, and material used for DBRs. Also, the improvement by using binary GaAs/AlAs Bottom-DBR is numerable studied by extracted thermal resistance form thermal simulation. The improvement in thermal performance makes this strategy useful for next generation green photonic device design.关键词：VCSEL;thermal analysis;high-speed;active region175|323|4更新时间：2020-08-12
- 摘要：The nonlinear characteristic of organic field-effect transistors (OFETs) is that the output characteristic curve of an OFET at low drain voltages is similar to the current-voltage characteristic curve of a diode. And this phenomenon is very common in OFETs' studies. Simonetti et al. proposed a model and successfully simulated this nonlinear behavior. However, the mobility value of OFETs extracted from transfer characteristics is generally gate voltage independent. In addition, the introduction of gate voltage dependent mobility makes the model inconvenient for practical use. In this paper, we improved that model by introduction of constant mobility, that is, gate voltage independent mobility. The improved model is not only convenient for use, but also reduces the number of required input parameters for calculation. With the improved model, the output characteristic curve of the bottom contact OFETs was successfully simulated, and the main factors that influence the nonlinear characteristic of OFETs were analyzed.关键词：organic field effect transistor;nonlinear injection;threshold voltage;field effect mobility122|109|0更新时间：2020-08-12
- 摘要：The absorption efficiency of top-incident organic thin-film solar cells(TOSCs) was improved by employing rectangle grating structure. The coupling mechanism between the hybridized surface plasmon polariatons and microcavity modes in ideal model of air/Ag1/active layer/Ag2/air (IMIMI) structure was analyzed. By tuning the period of the grating and the thickness of the active layer, the resonance region of the hybridized surface plasmon polaritons and microcavity modes are matched with the intrinsic absorption range of the organic materials. Due to the electric field enhancement effect of plasmon-cavity polaritons formed by the anticross-coupling between the microcavity modes and the surface plasmon polaritons, the absorption efficiency of the active layer is increased obviously, exhibits a increment of 19%.关键词：top-incident organic thin-film solar cells (TOSCs);surface plasmon polaritons;plasmon-cavity polaritons;rectangle grating162|96|4更新时间：2020-08-12
- 摘要：In order to optimize the performance of Mg-In-Sn-O thin film transistors (MITO-TFTs), MITO-TFTs were fabricated by radio frequency magnetron sputtering. The electrical properties on the effect of the annealing temperature and annealing ambient (O2 flow rate) were investigated. The 750℃ annealed MITO thin film with 400 cm3/min O2 flow is amorphous and the corresponding TFT shows best performance with saturation field effect mobility of 12.66 cm2/(V·s), threshold voltage of 0.8 V and on/off ratio reaches 107. Proper annealing will reduce defect and interface states density, improve the device performance effectively.关键词：MITO-TFT;oxide semiconductor;filed effect mobility;annealing temperature;annealing O2 flow rate122|190|3更新时间：2020-08-12
- 摘要：Optical radiation from any light source causes permanent damage to the color of high-responsivity Chinese traditional paintings. The white light emitting diode (WLED) is flexible, efficient, and can create similar color phenomena within different spectra, simplifying the adjustment of spectral irradiance distribution according to specific requirements. Establishing quantitative influence rules of WLED monochromatic light for protecting traditional paintings is the key. In this study, four typical monochromatic light sources (red, yellow, green, and blue) comprising the WLED spectrum were used to illuminate specimens of Chinese traditional light color paintings, then the CIE XYZ were measured periodically. Each specimen was manufactured with four organic pigments. The dominant wavelength, excitation purity, and lightness were calculated based on the data. Firstly, the curves showing the chromaticity change of different pigments under different light sources were analyzed to determine the color change rules. Secondly, the color change values were calculated to determine the influence of light sources on the painting. The quantitative influencing relationship on the dominant wavelength of painting color is 482 nm:510 nm:583 nm:650 nm=8 147:9 067:9 772:9 121. The quantitative influencing relationship on the excitation purity of painting color is 482 nm:510 nm:583 nm:650 nm=89 446:85 250:76 895:69 229. The quantitative influencing relationship on the lightness of painting color is 482 nm:510 nm:583 nm:650 nm=137:238:190:177. These results provide a reference for the spectral irradiance distribution of minimum-damage WLED for different light color paintings.关键词：Chinese traditional painting;white light emitting diodes (WLED);light damage;illumination protection178|123|1更新时间：2020-08-12
- 摘要：In order to detect copper in the cement quantitatively, on the basis of the characteristics of laser induced breakdown spectroscopy method, the laser induced breakdown spectroscopy system was set up. The standard addition method for the calibration method was adopted and five samples of cement containing different content of copper were made. According to the LIBS spectra, 213.598 nm and 219.958 nm were chosen as analysis lines. The spectrum data were preprocessed by Savitzky-Golary convolution smoothing method, and the fitting curves by Guass, Lorentz and Voigt fitting were compared. The calibration curves were set up by single variable linear fitting method. The Adjust R-Square of calibration curves of 213.598 nm and 219.958 nm are 0.994 8 and 0.986 4 respectively and the average relative errors are 3.20% and 5.78%. The results show that the accuracy of 213.598 nm as the analysis line is better than 213.598 nm for copper detection. This technique is reasonable to quantitatively analysis the metal elements in the cement by LIBS.关键词：laser induced breakdown spectroscopy (LIBS);metal elements;standard addition method;quantitative analysis;cerement158|169|8更新时间：2020-08-12
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