最新刊期
卷 38 ， 期 7 ， 2017
- 摘要：Quartz-enhanced photoacoustic spectroscopy(QEPAS) is a new technique for gas detection. It is revealed that QEPAS holds merits in many aspects, including small volume and high sensitivity. Therefore, it has become the hot researching topic of trace gas detection technique. This paper introduces the QEPAS technique principle and the structures of several different QEPAS systems. Furthermore, the development prospect of this kind technique is also predicted.关键词：QEPAS;trace gas detection;laser source;quartz tuning fork155|391|0更新时间：2020-08-12
- 摘要：Tb3+ doped transparent fluorosilicate glass ceramics containing SrF2 nanocrystals were prepared by melt-quenching method with subsequent heat treatment. The structure and luminescence properties of the as-made glass and glass-ceramics were investigated by X-ray diffraction(XRD), transmission electron microscope(TEM), transmittance spectra, photoluminescence spectra, fluorescence lifetime and X-ray excited luminescence spectra(XEL). The XRD results show that the precipitated crystalline in the glass matrix is SrF2 nanocrystal. The diffraction peaks become obvious and the crystal gradually increases with the increasing of the heat treatment temperature and time. Under 376 nm light and X-ray, much more intense emissions are observed in Tb3+ doped oxyfluoride glass ceramics containing SrF2 nanocrystals compared with the as-made glass. With the increasing of the heat-treatment temperature and time, the emission intensities are enhanced.关键词：Tb3+;SrF2nanocrystal;glass ceramic;spectroscopic property124|156|1更新时间：2020-08-12
- 摘要：In order to study the unique nonlinear optical properties and excitation mechanism, Cu-doped zinc oxide nanorods were excited by femtosecond pulsed laser. Under the excitation of 750 nm, the second harmonic peak is almost ignore meanwhile only the exciton peak and Cu doping related peak. The increase of the excitation intensity leads to a nonlinear increase of the intensity of the two emission peaks. The position of exciton peak exhibits a red shift meanwhile the position of defect peak does not move. If the excitation intensity further increases, the intensity of the defect related emission will decrease and the intensity of the exciton emission will increase continuously. When the excitation wavelength increases to 760 nm, the fluorescence spectrum of the sample can be clearly recognized the coexistence of the second harmonic peak and the exciton emission as well as the defect related emission. With the increasing of the excitation wavelength, the intensity of the second harmonic increases and the intensity of exciton emission and defect related emission decrease. At the excitation wavelengths of 790 nm and 800 nm, the exciton emission and defect related emission cannot be found, and the nonlinear spectrum is dominated by second harmonic generation. By selecting the appropriate excitation wavelength and excitation intensity, the transition of the luminescent color display can be realized, which makes Cu-doped ZnO nanorods as the potential of all-optical display.关键词：nonlinear optical;photoluminescence;metal doping;zinc oxide105|125|2更新时间：2020-08-12
- 摘要：Tetraphenylethylene and salicylaldehyde were combined together to synthesize five salicyladehyde schiff-base derivatives TPE-SA1, TPE-SA2, TPE-SA3, TPE-SA4 and TPE-SA5. FT-IR, NMR, MS, elemental analysis, UV-Vis, solution fluorescence, cyclic voltammetry electrochemical analysis and TG-DTA thermal analysis were used to study their structures, optical properties, thermal stability and electrochemical properties. The results show that these compounds have two UV absorption peaks around 260 nm and 370 nm in the dilute solution of THF. A significant aggregation-induced emission (AIE) effect is found through solution fluorescence tests with different V(THF)/V(H2O) mixed solvent of these compounds. Cyclic voltammetry (CV) was employed to characterize the ionization potential and electron affinity, respectively. These results show that all of them have good hole transporting ability and good electron transporting capability. TG/DTA analysis shows that the target products possess good thermal stability.关键词：tetraphenylethylene;salicyladehyde schiff-base derivatives;aie effect;thermal stability154|194|2更新时间：2020-08-12
- 摘要：A series of single phase Eu2+-activated barium phosphosilicates phosphors, Ba10-x(PO4)4(SiO4)2:xEu2+, with apatite structure were successfully synthesized by a novel two-step method and they exhibited interesting two-color emission at 414 nm (blue) and 504 nm (green), respectively. As a significant contrast, the phosphors prepared via traditional solid state reaction method, only showed single-color emission at 504 nm. The luminescent properties of these as-prepared phosphors are strongly dependent on the substitute sites of Eu2+ in apatite crystal structure and the two-color emission was proved due to the occupation of Eu3+ on two lattice sites of BaⅠ and BaⅡ in host material. Furthermore, the relative intensity of two emission peaks can be tuned readily via adjusting the substitution of BaⅠ site by Eu2+.关键词：phosphor;single phase;photoluminescence;Ba10(PO4)4(SiO4)2121|44|0更新时间：2020-08-12
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High-efficiency Flexible Organic Solar Cells with UV-ozone Treated Silver Modification ITO Electrode
摘要：Highly efficient heterojunction polymer solar cells based on ITO flexible electrode were developed with an UV-ozone-treated ultrathin silver interlayer combined with MoO3/PEDOT:PSS as modification materials. By optimizing UV-ozone-treated time of silver thin films, it could improve the power conversion efficiency (PCE) of the device based on the blend of poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C61-butyric acidmethyl ester (PC61BM) from 1.68% (without UV-ozone treatment) to 2.57% (Ag with 1 min UV-ozone treatment), which might be an AgOx layer formation that improves hole extraction and several promising characteristics, including high optical transparency, low sheet resistance and superior surface work function. Meanwhile, the devices with UV-ozone treated thin Ag layer together with MoO3 or PEDOT:PSS improves PCEs from 2.02% for the device with PET/ITO/MoO3 to 2.97% for the device with PET/ITO/AgOx/MoO3 and from 2.01% to 2.93% for device with PEDOT:PSS. In addition, the PCE of 6.21% of the flexible polymer solar cells based on poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b;4,5-b'] dithiophene-2,6-diyl-alt-(4-(2-ethylhe-xyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl(PBDTTT-EFT):[6,6]-phenyl C71-butyric acid methyl ester (PC71BM) as an photoactive layer was obtained. The efficiency improvement of the flexible OPV based on ITO is due to the increase of the work function of ITO by ITO/Ag/PEDOT:PSS or MoO3 composition.关键词：flexible organic solar cell;electrode modification;UV-ozone treatment;ultra-thin Ag124|202|0更新时间：2020-08-12 - 摘要：In order to reduce single-tube laser diode junction temperature and improve heat dissipation effects of the device, an optimized step sink structure was come up based on the thermal characteristic analysis of C-mount heat sink. The distribution of junction temperature and the lateral temperature of single-tube lasers were investigated. Under the conditions of the heat sink temperature of 298 K and continuous output power of 10 W, the junction temperature of typical C-mount heat sink package structure with 1.5 mm cavity length and 3 μm solder thickness is 343.6 K, and the thermal resistance is 4.6 K/W. By introducing level heat sink structure, the junction temperature of single-tube laser diode is 333.8 K and thermal resistance is 3.5 K/W. Theoretical calculation shows that the output power can be improved nearly 20%.关键词：solder thickness;thermal resistance;junction temperature;heat sink;output power192|534|2更新时间：2020-08-12
- 摘要：For perovskite solar cells, the morphology control of the perovskite thin-films is one of the key questions for improving the power conversion efficiency (PCE). To solve this issue, introduction of additive is proved to be an effective and simple way. Herein, polyacrylonitrile (PAN) was used as a solvent additive in the one-step CH3NH3PbI3 precursor solution, and the crystallization and surface coverage of the CH3NH3PbI3 films were controlled by means of adjusting its concentration, by means of adjusting its concentration to control the crystallization and surface coverage of the CH3NH3PbI3 films. Meanwhile, the film crystallinities, morphologies, and optical properties of CH3NH3PbI3 perovskite layers are characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) and UV-Vis. These experiment results show that the perovskite film properties can be optimized just by combining a small number of PAN, and PAN can strongly influence the crystallization process of forming pure CH3NH3PbI3 and facilitate forming the homogenous continuous films with fewer pinholes, which leads to a strengthened crystallization of CH3NH3PbI3 and remarkably improved coverage and light absorption of CH3NH3PbI3 on a planar substrate. After adding 1% mass fraction of PAN, the optimized PCE of CH3NH3PbI3 solar cells was increased from 1.31% to 8.13% for the planar cell structure. These results prove that PNA is an effective additive which could improve the quality of perovskite thin-films and potentially be a new candidate as an easily accessible additive during perovskite solar cells mass production.关键词：polyacrylonitrile;additive;crystal-growth;perovskite solar cells144|129|0更新时间：2020-08-12
- 摘要：The optical and structural properties of high-quality epitaxial Zn1-xMgxO films deposited by pulsed-laser deposition (PLD) were studied.Zn1-xMgxO films with~45% Mg incorporation were measured by EDS (Energy dispersive spectroscopy).XRD (X-ray diffraction) measurement results show that Zn0.55Mg0.45O films have a cubic phase structure without phase separation and are epitaxial grown along the c-axis of Al2O3 substrate.In the films,intense UVB optical pumped stimulated emission of this pure cubic-phase ZnMgO can be observed.The lasing threshold is about 22 kW/cm2.Lasing occurs at UVB wavelength of~310 nm under optical pumping.关键词：ZnMgO;PLD;threshold127|95|0更新时间：2020-08-12
- 摘要：Vertically aligned ZnO nanorods were prepared on sapphire substrates via a hydrothermal approach.The morphological,structural and optical properties were investigated by the scanning electron microscopy (SEM),X-ray diffraction (XRD) and photoluminescence (PL) spectra.These nanorods on substrates showed a good photocatalytic activity toward the methyl violet in the air atmosphere.The presence of oxygen and water vapor was essential for the photocatalytic oxidation.These nanorods could serve as the effective,convenient and recyclable photocatalysts in the air,which made them a promising photocatalyst candidate for the solid-contaminant treatments.关键词：ZnO;hydrothermal approach;photocatalyst166|87|0更新时间：2020-08-12
- 摘要：In order to reduce the operating voltage and increase the carrier mobility in zinc oxide thin-film transistor (ZnO TFT), ZnO TFTs with high-k NbLaO as gate dielectric layer were fabricated on indium tin oxide/glass substrate by radio-frequency magnetron sputtering at room temperature, and the electrical properties of the device were characterized. The fabricated ZnO TFTs exhibit excellent device performances. The saturation drain current can reach to 2.2 mA at gate voltage of 5 V and drain voltage of 10 V. The saturation mobility increases drastically up to 107 cm2/(V·s), which is one of the highest field-effect mobility values achieved in ZnO-based TFTs by room-temperature sputtering. The subthreshold swing and on-off current ratio are 0.28 V/decade and higher than 107, respectively. The relative mechanisms of high mobility, small subthreshold voltage swing and hysteresis phenomenon are discussed by analyzing the atom force microscope images of the NbLaO dielectric and ZnO active-layer film, and the low frequency noise behavior of the device.关键词：thin-film transistor;zinc oxide;radio frequency sputtering;high mobility118|116|1更新时间：2020-08-12
- 摘要：V-pits-containing InGaN/GaN blue LEDs were grown on patterned Si substrate by metal-organic chemical vapor deposition (MOCVD). A carrier confinement quantum well(QW)with a larger band gap and a light-emitting QW with a slightly smaller band gap were grown by tuning growth temperature. The effect of QW structure on the efficiency droop performance of V-pits-containing InGaN/GaN blue LED was investigated with some means to mix the two different types of QW. LED epitaxial wafers and LED photoelectric properties were characterized by high-resolution X-ray diffraction and LED test system. For the novel quantum well structure in which the confinement QW close to the n-side and the light-emitting QW close to the p-side, the droop of the external quantum efficiency is only 12.7%, which shows a more significant improvement compared with other QW structures (16.3%, 16.0%, 28.4%). What's more, only for this kind of structure, the internal quantum efficiency does not decrease sharply with the increasing of drive current at low temperature(T ≤ 150 K). The results show that a reasonable design of QW structure can significantly improve the effective overlap of electron-hole pairs in V-pits-containing InGaN/GaN QWs, promote carriers interaction between wells, and then improve carriers matching degree, inhibit electron leakage, retard efficiency droop, and finally enhance the photoelectric properties of devices.关键词：Si substrate;InGaN/GaN blue LED;efficiency droop;V-shaped pits;quantum well structure146|400|0更新时间：2020-08-12
- 摘要：In order to suppress the noise and improve the performance of the detector, AlSb caplayer was inserted between InAs layer and GaSb layer. The transfer matrix method was employed to solve the SchrÖdinger equation to get the wavefunctions and subband energies for electron and hole. The optical absorption coefficients were obtained by solving the Boltzmann equation with the balance equation method. The effects of AlSb caplayer on the intersubband optical transition were investigated in detail. The noise induced by the electron-hole combination can be suppressed efficiently when the width of AlSb caplayer reaches up to 1 nm. Two peaks of the optical absorption are observed at the mid-and-far infrared bandwidth indicating that InAs/AlSb/GaSb based type Ⅱquantum well system can be used as mid-and-far infrared photoelectric detector.关键词：two color optical absorption;InAs/AlSb/GaSb quantum well;balance equation method;electron-hole combination noise138|121|1更新时间：2020-08-12
- 摘要：ZnO nanorod arrays (ZnO NRAs) on FTO-glass substrates were prepared by chemical method, then Cu2O film was deposited on ZnO NRAs surface by using magnetron sputtering method. The crystal phase, morphology, UV-Vis absorbance spectra and photoelectric property were characterized by X-ray diffraction, X-ray photoelectron spectroscope, scanning electron microscopy, photoluminescence spectroscopy, UV-Vis spectrophotometer and electrochemical workstation, respectively. The photocatalytic activity was evaluated by the photocatalytic degradation of methyl orange (MO) under UV-Vis light irradiation. The results show that ZnO NRAs are wurtzite structure phase with diameter of 80-100 nm, length of 2-3 μm, and rod interval distance of 100-120 nm. Cu2O particles are the cubic phase with grain diameter of 100-300 nm and form a dense membrane layer on ZnO NRAs, which constitutes ZnO/Cu2O heterojunction nanorod arrays(ZnO/Cu2O HNRAs) structure. Compared with pure ZnO NRAs and Cu2O film, the absorption intensity in the visible region of ZnO/Cu2O HNRAs is significantly enhanced and the absorption wavelength redshifts. The charge transfer speed on the carrier transmission interface of ZnO/Cu2O HNRAs is faster, contributing to the separation of photoelectrons from hole. Irradiated under UV-Vis light for 65 min, the MO degradation efficiency of ZnO/Cu2O HNRAs is 94%, 18 times than that of pure ZnO NRAs and 1.7 times than that of pure Cu2O film.关键词：ZnO NRAs;ZnO/Cu2O HNRAs;photoelectrochemical properties;photocatalysis123|100|2更新时间：2020-08-12
- 摘要：In order to describe the spatial evolution of the light flash radiation produced by hypervelocity impact on 2A12 aluminum plate, the hypervelocity impact experiments were performed by using instantaneous optical pyrometer measurement system and two-stage light gas gun loading system at the conditions of the projectile incidence angle of 30° and the different impact velocities. The maximum flash radiant intensity and the maximum flash radiant temperature were obtained based on the experimental data treatments from flash radiant intensity and radiant temperature created by hypervelocity impact on 2A12 aluminum plate. The maximum flash radiant spatial evolutionary model near the impact point was established from plenty of experimental data. By fitting the experimental data with Origin software, the fitting function relations were obtained about the maximum flash radiant intensity and the radiant temperature with the distance from the detection point to the impact points. The experimental results also shown that the maximum flash radiant intensity and radiant temperature had few differences at the same surface of the ellipsoid positions, when the impact velocity and the impact angle were closen to the same conditions. All these verified that the light flash radiation expanded approximately the ellipsoid shape outward, and maximum flash radiant intensity and radiant temperature smaller from the collision point more far with the plasma cloud expansion; the maximum flash radiant intensity and radiant temperature will increase with increasing of the impact velocities at the same surface of the ellipsoid positions of the different detection points. The research has an important applied value in the field of missile interception, astrophysics and deep space exploration.关键词：hypervelocity impact;flash radiant intensity;flash radiant temperature;spatial evolutionary model;rules of flash radiant evolution126|294|4更新时间：2020-08-12
- 摘要：In order to improve the efficiency of LED plant light source, the LED array of red and blue light source was designed and optimized based on Taguchi method. The work was simulated by MATLAB software, then the largest influential factor which influenced on the ratio distribution of red and blue light photon numbers (R/B) at a distance of 10 cm from the plant light source was analyzed by ANOVA method. At last, the best results were tested by TracePro optics software. The results show that the optimal combination consists by the arrangement of one blue LED chip on the center and six red LED chips on the ring on the concave surface with the curvature radius of 50 mm, and the distance of LED chips is 10 mm. The distance of LED chips has the greatest impact on the distribution of R/B, accounting for 35.17%. Of course, the arrangement of LED chips can not be ignored, because it occupies 28.05% of the impact of the ratio.关键词：light-emitting diode;plant light source;curved surface;Taguchi method;ANOVA195|114|4更新时间：2020-08-12
- 摘要：In order to realize LED rectangular collimated beam, a fast design method for LED lens with high optical collection efficiency was presented. Two free-form surface contours were designed based on step-by-step method, edge ray theory and geometrical optics law. Based on them, two free-form surfaces were obtained quickly and the lens was constructed. When the ratio of the length between lens inner surface and LED to the LED size is 6, the full width at half maximum (FWHM) of the system is 2.3°×1.15°, and the light collection efficiency is about 82.6%, which can effectively realize rectangular collimated beam. As the ratio increases, the size of the lens becomes larger, the FWHM becomes smaller, and the collection efficiency of the lens becomes higher. According to the design parameters, a lens was manufactured and the simulation results were experimentally verified. This method provides an effective way to realize the rectangle collimated beam of LED.关键词：rectangular collimated beam;high optical collection efficiency;step-by-step method;free-form surface;LED213|182|1更新时间：2020-08-12
- 摘要：We report a method for determination of melamine based on fluorescence recovery of carbon quantum dots (CQDs). It was found that the fluorescence intensity of CQDs can be efficiently quenched by Hg2+. And a turn-on fluorescence signal can be observed if melamine was added. The results showed when the concentration ratio of mercury ions to carbon quantum dots was 15:10000, the concentration of carbon quantum dots was 4.0 g/L and the pH value was 7.5, the response was linearly proportional to the concentration of melamine within the range of 3.0-60 mg/L, the limit of detection (3σ/k) was 2.2 mg/L. The method was successfully applied to the determination of melamine in real sample with satisfactory recoveries (95%-103%)关键词：carbon quantum dots;fluorescence recovery;determination;melamine132|178|3更新时间：2020-08-12
- 摘要：In order to offer the quick analysis of concentration of pesticides residues in agricultural products, a mixed procymidone-honey system was built and studied according to the principle of fluorescence spectrum. The relationship between the fluorescence intensity and the procymidone content in honey was also analyzed. With the aid of steady fluorescence spectrometer, the fluorescence spectra of procymidone solution and honey solution were detected respectively. The fluorescence emission peaks of pure honey and procymidone are found at about 342 nm and 390 nm. The fluorescence peak position has a red shift (from 342 nm to 390 nm) with respect to an addition of procymidone (0.1 g/dL) into honey, indicating the interaction between procymindone and some substances in honey. By using software program of Origin8.5 which is used to process and analyze data, the linear fitting is done of the fluorescence peak intensity of the honey and the content of procymindone. The results show that the prediction models between the fluorescence intensity and procymidone content in honey has a good linear relationship. The function model is I=188504.75x+384764.33, and the correlation coefficient is 0.99. The experimental results under the same conditions show that the accuracy of the function model is 96.8%-100%. The results can be concluded that the determination of procymidone is effective and reliable for the concentration testing of procymidone residues in other agricultural products.关键词：fluorescence spectrum;honey;procymidone;concentration detection159|103|4更新时间：2020-08-12
- 摘要：Deficiencies of X-ray digital imaging system are mainly shown in the following aspects:imaging end coupling constrained, bottleneck constrained by microfocus, photonic defect and constrained quantum noise, etc.. It is difficult for the effective image filtering through traditional digital image processing techniques to be realized. Its effect is further constrained by the complicated filtering algorithm. To improve the optical transmission capacity and system noise immunity of X-ray imaging system, in this paper, the thermal excited X-ray source and X-ray image intensifier were taken as examples, a number of imaging technical difficulties were explored from system level, and a integral filtering method on X-ray imaging was put forward. Then, the frequency-fixed leaden raster was taken as the tested object. By changing the object-image relation of relay optical coupling system, the image place frequency could be changed continuously within a certain range. By lots of experimental data, the accurate fitness of OTF (optical transfer function) can be realized under different integral time conditions. It is proved that this filtering method can not only effectively suppress the quantum noise caused by hot trigger source in avoid of photonic defect on image, but also obviously improve the optical transmission capacity of imaging system from angles of OTF integral effect and normalized baseband transmission characteristics respectively. Finally, the superiority of this filtering method was testified from perspective of contrasting frame-adding and integral filtering.关键词：X-ray;contrast;integrator filter;modulation transfer function;image intensifier124|81|1更新时间：2020-08-12
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