最新刊期
卷 41 ， 期 2 ， 2020
- 摘要：In recent years, all-inorganic cesium lead halide(CsPbX3, X=Cl, Br, I) perovskite quantum dots have attracted much attention due to their high color purity, tunable emission wavelength(410-760 nm), narrow full width at half maximum (12-42 nm), high photoluminescence quantum yield(up to 95% or more) and solution process ability. They have exhibited promising potential applications in displays and lightening. In this review, we firstly introduce the developing liquid-phase synthetic methods of all-inorganic cesium lead halide, such as high-temperature injection strategy, one-pot method, anion exchange approach, supersaturated re-crystallization method, and so on. Secondly, we present the influencing factors, such as size, morphology and crystal tailoring as well as the effects of composition, reaction temperature and dopants, on the photoluminescence properties, and the progress on all-inorganic lead-free perovskite quantum dots. We also summarize the advances in the light-emitting diodes based on all-inorganic quantum dots. Finally, the challenges and opportunities in the future are also highlighted.关键词：all-inorganic perovskites;quantum dots;synthetic methods;optoelectronic properties;light-emitting diodes604|843|17更新时间：2020-08-12
- 摘要：Graphene oxide is a chemical reagent, which is commonly used in the industry. In order to test its photothermal conversion performance, an experiment was made. The advanced Hummers method was used to prepare graphene GO dispersion, and the PVA-GO composite membrane was prepared by electrospinning. The absorbance performance was analyzed by UV reflectance spectroscopy(UVRS). The results show that the amount of evaporated water of PVA-GO was increased with the increase of GO mass concentration. This phenomenon could be measured by the electronic balance. When the GO mass concentration reached 7%, the performance of PVA-GO composite membrane would be better. The PVA-GO composite membrane was electrospinning into a fibrous network structure, which has a good photothermal conversion performance. The surface characteristics of the PVA-GO composite membrane were analyzed by SEM. The PVA membrane without added GO was a filamentous structure with a smooth surface and uniform fiber diameter distribution. When the PVA was filled with 7% GO, the fiber structure was reticular and part of the GO uniformly wraped the fiber filament. In the vacuum environment, the density of the PVA-GO composite membrane increased after the 423 K high temperature treatment and the degree of GO attaching fiber filaments increased. The evaporation rate of the PVA-GO composite membrane was 0.81 kg/(m2·h) when irradiated with 980 nm infrared laser. The evaporation efficiency could reached 51%, which was about two times that of the polyvinyl alcohol membrane. This can not only improve the utilization of light evaporation, but also provide reference for the desalination industry.关键词：electrospinning experiment;polyvinyl alcohol;photothermal conversion performance;graphene oxide;seawater fresh water140|346|1更新时间：2020-08-12
- 摘要：La2CaB10O19(LCB) is a nonlinear crystal which can produce 355 nm ultraviolet (UV) laser output through the third harmonic generation (THG) of Nd:YAG laser, its optical property is comparable to that of commercial LiB3O5(LBO) crystal, with an obvious advantage in its moisture resistance. In this paper, the THG process of 355 nm UV laser output with LCB crystal was optimized, and the walk-off compensating method was used to improve the conversion efficiency of laser output. By adding a calcite crystal compensator cut at θ=45° to the optical axis with a thickness of 1.2 mm, the output power of 355 nm can be increased from 12 W to 20 W under the laser parameters of 60 ns pulse width and 10 kHz repetition rate. When the pulse width is 25 ps and the repetition rate is 10 Hz, the conversion efficiency from 1 064 nm to 355 nm is improved from 28.3% to 35.2%.关键词：LCB;non-linear optical crystal;ultraviolet laser;third-harmonic generation;walk-off compensation142|139|1更新时间：2020-08-12
- 摘要：InGaN-based yellow-green dual wavelength light-emitting diodes (LEDs) with seven pairs of yellow multiple quantum wells (MQWs) and a pair of green QW were grown on patterned Si substrate by metal-organic chemical vapor deposition (MOCVD). Meanwhile the effect of p-GaN spacer layer before the electron blocking layer (EBL) on the carriers distribution and external quantum efficiency (EQE) was investigated. LED photoelectric properties were characterized by LED test system. The results support the integrated EL intensity ratio of green/yellow peak increases with increasing current density at 100 K. And the integrated EL intensity ratio of green/yellow peak increases with decreasing temperature from 300 K to 100 K at a forward current density of 5.5 A·cm-2. These experiment phenomena indicate that the radiative recombination of carriers occurs in the QW nearest the p-layer. The peaked EQE are 29.0%, 29.2% and 28.2% with the thickness of p-GaN spacer layer 0, 10, 30 nm of three samples. The peaked EQE of three samples decrease because the active region is further from the p-layer and holes are distributed nearer the p-layer with increasing thickness of p-GaN spacer layer. p-GaN spacer layer can effectively reduce the movement (33 nm) of green peak with increasing current density and the cryogenic emission spectrum can be regulated.关键词：Si substrate;yellow-green dual wavelength LEDs;p-GaN spacer layer;emission spectrum211|211|0更新时间：2020-08-12
- 摘要：Yb3+, Eu3+, La3+ co-doped CaF2 upconversion phosphors were synthesized by a modified two-step high temperature solid phase method. On the basis of fluorescence quenching theory, the luminescence properties of CaF2:Yb3+/Eu3+ materials were adjusted by changing the doping concentrations of La3+, and the white upconversion luminescence (UCL) of these materials was obtained under a 980 nm laser. In this UCL system, Yb3+ not only sensitizes Eu3+ but also cooperates with neighboring Yb3+ to emit green luminescence in the wavelength range of 480-540 nm. This green luminescence just happens to be an important component of white light. In addition, Eu3+ ions act as activators and emit both red and blue luminescence, providing two other elements in the tri-color light. Fluorescence dynamical analysis indicates that an efficient energy transfer exists between the Yb3+-dimers and Eu3+ ions. It is remarkable that the white UCL can be achieved from the 1% La3+-doped sample, and the color coordinate is (0.311, 0.340).关键词：upconversion;fluorescence quenching;cooperative luminescence;white luminescence165|183|3更新时间：2020-08-12
- 摘要：YAG:5%Dy3+ and (Ce0.01DyyY0.99-y)3A15O12 (y=0%,1%,3%,5%,7%,9%) phosphors were prepared by high temperature solid-state method. XRD results showed that the addition of H3BO3 could effectively reduce the crystallization temperature of YAG crystal and prevent the formation of the intermediate phase YAlO3. The results showed that they were still the cubic phase of the samples for Dy3+, Ce3+ doped Y3Al5O12 by adding H3BO3 after calcination at 1 450℃ for 6 h. With the increase of Dy3+ doping concentration, the main diffraction peak (420) shifted to a small angle. Under λem=583 nm, the absorptions of Ce3+ and Dy3+ co-doped samples at 342 nm were decreased than that of only Ce3+ doped sample, and the absorptions at 351 nm significantly enhanced compared with that of only Dy3+ doped sample. Under 351 nm excitation, with the increase of Dy3+ doping concentration, the emission intensities at 526 nm decreased for Dy3+ and Ce3+ co-doped Y3Al5O12 samples, but the emission intensities at 583 nm first increased and then decreased, which indicated that under the excitation of 351 nm, part of the energy transfer from Ce3+ to Dy3+ existed. Under 465 nm excitation, Ce3+ and Dy3+ co-doped samples only contained Ce3+ emission peak, and with the increase of Dy3+ concentration, emissions of Ce3+ ions decreased. When the concentration of Dy3+ was 3%, the emission intensity of Dy3+ reached the maximum, and the energy transfer efficiency of Ce3+→Dy3+ was 15.7%. Under 405 nm excitation, with the increase of Dy3+ concentration, the lifetime of Ce3+ decreased for Ce3+ and Dy3+ co-doped samples. The critical distance of Ce3+→Dy3+ energy transfer was 3.464 nm, which was the resonance energy transfer of the electric quadrupole-electric quadrupole interaction.关键词：Dy3+ and Ce3+ co-doped Y3Al5O12;luminescence properties;energy transfer;energy level lifetime;multipolar interaction166|211|4更新时间：2020-08-12
- 摘要：Developing novel inorganic hole transport layer materials is one of the major challenges for the commercialization application of the perovskite solar cells. The preparation of WS2 nanosheets and their application for hole transport layer in perovskite solar cells are investigated in this work. WS2 nanosheets were prepared by liquid phase supersonic exfoliation method. Then by using solution spin-coating method the WS2 nanosheets thin films were introduced as the hole transport layer (HTL) material in the planar heterojunction perovskite solar cells. The results indicate when the concentration of WS2 nanosheet solution is 1 mg/mL, the thickness of the WS2 nanosheet thin films is suitable for the application to the hole transport layer, and the perovskite active layers grown on them have high film quality and good crystallinity. Finally a photoelectric conversion efficiency of 6.3% is obtained. In this study, we demonstrate an effective new use of WS2 nanosheets HTL in the perovskite solar cells.关键词：WS2 nanosheets;liquid phase supersonic exfoliation;perovskite solar cells;hole transport layer148|274|1更新时间：2020-08-12
- 摘要：The performance of double-junction tandem organic solar cells (OSCs) was improved by optimizing interlayer (IL), cathode interface layer (CL) and active layer. Firstly, by employing low work function metal nanoparticles (Mg, Ag, Al and Ca) as IL, the optimal performance was obtained in OSC with IL of 0.1 nm Al. Comparing to tandem OSCs without IL, the power conversion efficiency (PCE) of OSCs with Al IL was increased by 50.9%. Secondly, by employing different low work function metals (Mg, Al and Ca) as CL in tandem OSCs, the optimal performance was obtained in OSC with Mg CL. Compared with tandem OSCs with Al CL, PCE of OSCs with Mg CL was increased by 20.7%. Finally, narrow bandgap material DTDCTB was adopted to replace medium bandgap material boron subphthalocyanine chloride (SubPc) as active layer of the back sub-cell. Compared with tandem OSCs using only SubPc donor material, the PCE was increased by 30.2%. By using bulk heterojunctionstructure in both front and back sub-cells, PCE of tandem OSCs reached 4.04%. Compared with PCE (2.1%) of original non-optimized OSCs, the PCE of optimal OSCs was increased by 92.4%.关键词：tandem organic solar cell;intermediate layer;cathode interface layer;bulk heterojunction146|445|0更新时间：2020-08-12
- 摘要：PbSe/TiO2 composite nanotubes (NTs) are successfully synthesized by solution method. The characterizations indicate the as-prepared samples are composed of PbSe and TiO2. It is found that the surface of PbSe NTs is uniformly coated with a TiO2 thin layer. Under illumination with xenon lamp, the photocatalytic activity is investigated by degradation of methyl orange dye. As a result, PbSe/TiO2 NTs heterostructures display a better photocatalytic degradation rate, almost 4.5 times as high as that of PbSe NTs. Furthermore, the photocatalytic stability of PbSe/TiO2 composite NTs is also studied.关键词：PbSe;TiO2;nanotube;heterojunction;photocatalysis135|118|1更新时间：2020-08-12
- 摘要：Cadmium selenide(CdSe) is a classic Ⅱ-Ⅵ semiconductor material. Most often, CdSe with CdS can form ternary alloys CdSexS1-x (0 ≤ x ≤ 1). CdSexS1-x has a large application in transparency electrode of CdTe thin-film solar cells and optoelectronic device. It is helpful to improve CdSexS1-x application value in photoelectric devices studying of its photoelectric properties. This paper calculates and analyzes the electronic structure and optical properties of CdSexS1-x ternary alloys with plane pseudo-potential mathod based on first-principles calculations. The calculated results are compared with the experimental results. The calculation results show that the lattice constant of CdSexS1-x ternary alloy crystal forming after Se substitutes S partly or wholly presents a tread of linear increase with the increase of Se content. Except Se:S=1:1 the crystal system of CdSexS1-x alloy with other ration does not change, forbidden gap decreases gradually and the peak value of state density gradually shifts towards the direction of high energy with the increase of Se content. In addition, the absorption edge exhibits a blue shift with Se concentration increasing. At the same time, reflectivity, loss-function and refractive index show their peak values when Se concentration x reaches 0.5. The calculation results are in good agreement with the experiment results.关键词：CdSexS1-x;first-principles;electronic structure;optical properties169|221|0更新时间：2020-08-12
Synthesis and Properties of Materials
- 摘要：To improve the performance of 9xx nm high power semiconductor lasers, the doping profile of n-cladding layer and p-cladding layer is adjusted to reduce the internal loss. A high energy band gap GaAsP was introduced between the active region and the waveguide layer to reduce the leakage of carriers in the active region. A broad area laser with internal loss of 1.25 cm is designed and fabricated. The device with maximum output power of 26.5 W is obtained. The maximum electrical-optical power conversion efficiency is 72.4%, which is obtained when the output power is 10.5 W. The slope efficiency is 1.16 W/A.关键词：laser diode;internal loss;free carrier absorption195|234|0更新时间：2020-08-12
- 摘要：Full-spectrum LED has the advantages of high spectral similarity with the visible spectrum of sunlight, high color saturation and fidelity, close to 100 color rendering index and no blue light hazard, and is considered as a mainstream direction of semiconductor lighting technology in the future. Starting from the concept and characteristics of full-spectrum LED, this paper describes the advantages of full-spectrum LED scheme compared with the traditional scheme. The mainstream full-spectrum LED schemes and existing problems are described. Finally, the work done by the researchers in perfecting the spectrum and simplifying the process is introduced from two aspects of the development of new phosphors and the synthesis of multi-color full spectrum. And the application of full spectrum LED in the future is envisaged.关键词：full-spectrum;mixture;color rending index;color temperature600|1580|2更新时间：2020-08-12
Device Fabrication and Physics
- 摘要：L-cysteine modified Mn-doped ZnS quantum dots (Mn:ZnS QDs) were synthesized by hydration. A rapid and highly sensitive method for the determination of tetracyclines (TCs) residues in honey was established by using the internal filtration effect of TCs on Mn:ZnS QDs excited by phosphorescence. TCs have a strong ultraviolet absorption at the optimal phosphorescence excitation wavelength 289 nm of Mn:ZnS QDs. When TCs is present in the Mn:ZnS QDs solution, the excitation wavelength is absorbed by TCs to a certain extent, and the phosphorescence signal decreased. To be represented by doxycycline (DTC), the linear relationship between Mn:ZnS QDs phosphorescence signal and DTC concentration was established, and the quantitative detection of DTC was realized. Under the optimized conditions, the phosphorescence intensity decreased with the increase of DTC concentration and the relative phosphorescence intensity change ln(P0/P) showed a good linear relationship with the increase of DTC in the range from 0.05 to 150 μmol·L-1. The regression equation was lnP0/P=0.01758C(DTC)+0.01351(R2=0.999), the detection limit is 0.009 7 μmol·L-1. The actual sample honey was tested, the recovery rate was 92.4%~110%. The Mn:ZnS QDs phosphorescence probe developed in this study has good repeatability and stability for the detection of TCs residues. It can be used for the rapid and highly sensitive detection of TCs residues in honey.关键词：Mn-doped ZnS quantum dots;phosphorescence probe;doxycycline;honey;tetracyclines144|159|1更新时间：2020-08-12
- 摘要：Aiming at the problems existing in traditional hydraulic system detection, such as low measuring accuracy, large size and complex structure, a kind of integrated target flow sensor based on fiber Bragg grating (FBG) was designed. This paper analyzed the principle of FBG and target type flow sensing, and designed an integrated target with a compact composition, which was easy to seal and disassemble. Double FBG symmetrical distribution was respectively placed on the central axis of the two surfaces of the cantilever beam. This differential form can increase the sensitivity well and solve the cross-sensitivity phenomenon of strain and temperature. Through the simulation analysis of fluid state by FLUENT software, it is concluded that the integrated target structure has less influence on fluid state than the traditional structure. In the hydraulic experiment, there is a good linear relationship between the change amount of the center wavelength of double FBG and the mass loaded on the target, and the sensitivity is twice as high as that of a single FBG, with good stability and reliability.关键词：equal intensity cantilever beam;fiber Bragg grating;flow sensor;target type structure165|274|5更新时间：2020-08-12
- 摘要：Coherent free-space optical communication with 8-quadrature amplitude modulation (8-QAM) using joint algorithm of amplitude compensation and digital phase recovery is proposed. Compared with traditional free-space optical communication schemes, the scheme we proposed not only can restore the signal without requiring the knowledge of instantaneous channel state information, but also has higher spectral efficiency. Numerical studies show that the bit error rate of the proposed system is four orders of magnitude lower than that of the 8-QAM system without joint algorithm, when the frequency offset f0=20 MHz between the receiver and the transmitter, the lasers joint linewidth Δf=10 kHz, and the signal-to-noise ratio is 20 dB for a lognormal turbulence channel with σ=0.25 and phase noise with σφ2=0.07.关键词：free-space optical communications;quadrature amplitude modulation (QAM);coherent detection197|134|0更新时间：2020-08-12
Luminescence Applications and Interdisciplinary Fields
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