最新刊期
卷 35 ， 期 11 ， 2014
- 摘要：NaGdF4:Yb3+,Er3+ and Na(Y, Gd)F4:Yb3+,Er3+ crystals were synthesized by hydrothermal methods. The size and luminous intensity of the particles can be adjusted by changing the temperature, time, pH value, the molar ratios of trisodium citrate to Ln3+ ions, F- to Ln3+ ions and Gd3+ to Y3+ ions. Diffraction (XRD), photoluminescence (PL) spectra, and field emission-scanning electron microscopy (FE-SEM) were used to characterize and analysis the samples. The low pH value is found to promote the formation of GdF3, while NaGdF4 benefits from high pH value. The increasing of trisodium citrate content can restrain the growth of the particle to reduce the luminous intensity. The addition to the fluorine content accelerates the growth along (001) crystal orientation relative to (101) crystal orientation and further enhances luminous intensity. With the increasing of doped Y3+ content, particle size increases, while the luminous intensity show a trend of rising after decline first.关键词：NaGdF4;Na(Y;Gd)F4;particle size;luminous intensity110|36|0更新时间：2020-08-12
- 摘要：An MSM solar-blind UV photodetector was fabricated on Mg0.29Zn0.71O thin film, which showed a large responsivity of 27.9 A/W at 30 V bias (268 nm). The ultra thin phase-transition layer leads to the improvement of the metal-semiconductor contact and more internal gain. The results provide a new choice to realize high performance MgZnO-based solar-blind UV detectors.关键词：cubic MgZnO;deep-ultraviolet photodetector;photoconductive gain115|134|1更新时间：2020-08-12
- 摘要：Plasmon characteristics in nitrogen-doped graphene nanostructures are studied by time-dependent density functional theory. The pyridinic-nitrogen doping does not affect plasmon characteristics of graphene nanostructures, while the substitutional-nitrogen doping affects plasmon resonances of graphene nanostructures due to two main competing factors: The reduced symmetry of graphene nanostructures and the increase of the electron densities. After doped with substitutional-nitrogen, low-energy spectra of hexagonal graphene nanostructures are red-shifted. For rectangular graphene nanostructures, along the armchair-edge direction, the main low-energy spectra always show blue-shifts. However, along the zigzag-edge direction, the substitutional-nitrogen doping has little effect on the main lower-energy collective excitation.关键词：plasmon;nitrogen-doped graphene nanostructures;time-dependent density functional theory98|107|1更新时间：2020-08-12
- 摘要：Sr2-xZnSi2O7:xEu3+ red phosphors were synthesized with mesoporous MCM-41 as silica source via a low-temperature hydrothermal route with further calcining. The results indicate that Sr2ZnSi2O7 phase appears in the hydrothermal reaction product synthesized at 150 ℃ for 16 h, and pure phase Sr2ZnSi2O7 is obtained by further calcining at 950 ℃ for 3 h. Sr2-xZnSi2O7:xEu3+ phosphors can be effectively excited by 392 nm near-ultraviolet radiation and show the typical emission spectra of Eu3+. The prominent emission transition is at 615 nm assigned to 5D0→7F2. The structure of Sr2ZnSi2O7 is not affected by doping appropriate amounts of Eu3+. Sr2-xZnSi2O7:xEu3+ phosphor with x=0.10 has the highest Eu3+ emission intensity.关键词：Sr2ZnSi2O7:Eu3+;red phosphors;hydrothermal treating;MCM-41105|90|0更新时间：2020-08-12
- 摘要：The orthorhombic CaZrO3:Ln (Ln=Pr3+, Sm3+, Tb3+, Dy3+, Tm3+) were successfully synthesized by solid-state reaction method. The crystalline structure of the samples were characterized by X-ray diffraction (XRD). The luminescence properties were investigated using photoluminescence spectra. Under appropriate near UV- or blue light-radiation, CaZrO3:Pr3+ showed strong green light emission, CaZrO3:Sm3+ showed well reddish orange light in the range of 550-700 nm, and CaZrO3:Tm3+ generated well blue light emission. The results indicate that spectral tuning can be realized by adjusting active ions in CaZrO3, thus rare earth ions-doped CaZrO3 phosphors can be exploited as new luminescence materials.关键词：CaZrO3;rare earth ions;optical properties;spectral tuning114|40|0更新时间：2020-08-12
- 摘要：TbPO4·nH2O were synthesized via low temperature hydrothermal method by controlling the molar ratio of PO43-/Tb3+. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and photoluminescence spectra (PL) were used to characterize the as-synthesized products. The influence of the ratio of PO43-/Tb3+on the morphology, crystal structure and luminescent properties were studied. The possible growth mechanism was proposed. When the molar ratio of PO43-/Tb3+ is up to 60:1, the powder is cocoon-like with a diameter of 100-200 nm, and its emission intensity is the strongest. The ratio of PO43-/Tb3+ plays an important role in the morphology and the luminescent properties.关键词：TbPO4·nH2O;hexagonal;luminescence properties;hydrothermal synthesis95|24|0更新时间：2020-08-12
- 摘要：In this contribution, a simple method for synthesizing the TiO2 nanoporous electrodes processed at low temperature was explored. Specifically, three types of inorganic binders, i.e. ammonia, hydrochloric acid and deionized water, mixed with ethanol as dispersant were used to prepare the TiO2 pastes. The effects of the mass ratio between the inorganic binders and dispersant on film properties were particularly studied. Moreover, the complete all-solid-state dye-sensitized solar cells were fabricated based on prepared TiO2 electrodes. Combining the viscosity test of TiO2 paste and the micro-morphology measurement to the photoelectric characterization in time-/frequency-domain, the comprehensive analysis presents the interrelation between macroscopic photovoltaic performance and microscopic charge carrier transport mechanisms. Eventually the optimal inorganic binder and its mass ratio versus dispersant has been found out, and the maximum power conversion efficiency of the corresponding cell can reach up to 1.45%.关键词：titanium oxide;low-temperature processed;photoelectrode;all-solid-state dye-sensitized solar cells;power conversion efficiency125|194|1更新时间：2020-08-12
- 摘要：Y2O3:Pr3+,Yb3+ nanoparticles were synthesized by femtosecond pulsed laser ablation method, and the up-conversion properties of the particles were investigated. The nanoparticles can be obtained under certain laser power intensity. With the increasing of laser intensity and pulse repetition frequency, the yield of the nanoparticles increases. The diameters of these spherical particles are smaller than 50 nm. An emission band centered at 510 nm can be observed in the emission spectrum under 976 nm excitation. The emission intensity increases with the amount of the nanoparticles.关键词：laser ablation;up-conversion;rare earth oxide97|62|1更新时间：2020-08-12
- 摘要：Tm3+/Yb3+ doped NaGdF4 luminescent powder with different Na sources and ion ratios were synthesized by ball milling method, and part of samples were treated under high temperature. In all selected molar ratios of the ions, n(RE):n(Na):n(F)=1:1:4 is the best. The up-conversion luminescence of the samples with this ratio is the strongest before and after high temperature treatment. After high temperature treatment, the intensity of visible light emission increases significantly. XRD results show that Tm3+ and Yb3+ have doped in the lattices of NaGdF4. After high temperature treatment, part of β-phase and amorphous phase turn to α-phase, which results in the crystallinity improving. HRTEM image also shows that α- and β-phase coexist in the sample. The excitation of 980 nm laser hardly has effect on the paramagnetism of the samples, but the changing magnetic field has negative effect on the up-conversion luminescence of the samples.关键词：ball milling;upconversion;paramagnetism;luminescence111|115|0更新时间：2020-08-12
- 摘要：Hybrid white organic light-emitting device based on fluorescent layer combining with phosphorescent doping layer was fabricated, in which fluorescent material BePP2 acted as blue emitter layer, phosphorescent material GIrl and R-4B doped into CBP:Bphen bipolar type host acted as green and red emitter layer, respectively. The ultrathin spacer layer was constructed by inserting a 2.0 nm thin layer of TPBI between red and green emitting layer. In the quantum well structure, BePP2 and TCTA acted as the potential well layer and the potential barrier layer, respectively. The maximum luminance and current efficiency are 21 682.5 cd/m2 and 23.73 cd/A, respectively. The Commission Internationale de I’Eclairage(CIE) coordinates of the device vary from (0.345,0.350) at 7 V to (0.340,0.342) at 14 V when the number of potential barrier layer is two. In comparison with the reference device without quantum well structure,the device with two barrier layers achieves a maximum power efficiency of 8.07 lm/W, a low CIE coordinates changing of ±(0.005, 0.008), and a high color rendering index of 83.关键词：organic semiconductor;phosphorescent material;fluorescent material;quantum well;white organic light-emitting devices103|155|0更新时间：2020-08-12
- 摘要：An interesting photo-annealing phenomenon has been successfully demonstrated in polymer solar cells (PSCs) with an inverted device architecture by employing solution processable Cs2CO3 as electron extraction layer. As the photo-annealing time attained 15 min, the PSC device harvested a high power conversion efficiency (PCE) of 8.35% with a short-circuit current density of 15.8 mA/cm2, an open-circuit voltage of 0.76 V and a fill factor of 69.5%. It is worth mentioning that this fill factor is among the highest values in all reported BHJ devices based on PTB7. X-ray photoelectron spectroscopy results reveal that the photo-annealing phenomenon derived from the transformation of Cs2CO3 into Cs2O and CO2 during photo irradiation. This evidence was further verified in PSCs by employing four-week-irradiation Cs2CO3 solution as electron extraction layer. By using the irradiated Cs2CO3 solution, the PSC devices did not show photo-annealing phenomenon and presented almost the same device performance in comparison with those photo-annealing devices. The results indicate that this photo-annealing phenomenon is very meaningful for the realization of future high-performance all-solution processed PSCs.关键词：photo annealing;polymer solar cells;solution processable;Cs2CO398|131|0更新时间：2020-08-12
- 摘要：One-direction-emission red transparent organic light-emitting device employing Ag/organic/Ag anode and Ag/Ge/Ag cathode was fabricated. The photonic tunneling effect existing in the multilayer electrode results in the alternative transmission property of the electrode, and the device employing the multilayer electrode exhibits one-direction-emission property. At the same bias voltage, the brightness of the non-emission side is less than 3% of that of the emission side. The brightness from emission side and non-emission side are 15 550 and 387 cd/m2 at 9.5 V, respectively. The devices attain its maximum current efficiency of 7.01 cd/A at 7.5 V, and the brightness from emission side and non-emission side are 4 968 and 151.7 cd/m2, respectively. Besides, the device also shows an excellently angle-stable characteristic. As the viewing angle increases from 0° to 60°, the chromaticity coordinate only shift (-0.002,0.001), which should be attributed to the relatively high transmission and low reflectivity of the Ag/Ge/Ag cathode.关键词：organic light-emitting device;transparent;one-direction-emission127|150|2更新时间：2020-08-12
- 摘要：The actual situation of fiber coupling diode laser module based on mini-bars was simulated by ZEMAX. Twenty two pieces of mini-bar with output power of 60 W were arranged in two stack arrays as laser source. The beam could be coupled into the fiber of 400 μm core diameter with 0.22 numerical aperture by collimating, combining and focusing. The output power of the fiber coupling module is more than 1 200 W, and the coupling efficiency is about 92%.关键词：diode laser;ZEMAX;mini-bar;optical fiber coupling104|190|1更新时间：2020-08-12
- 摘要：Indium gallium zinc oxide thin film transistors (IGZO-TFTs) with bottom-gate top structure were fabricated on n-type silicon substrates using radio frequency (RF) magnetron sputtering method. Three kinds of metal material such as Au, Cu, and Al were used to fabricate electrode, respectively, and the effects of different electrode materials on IGZO TFT performance were investigated. The output characteristic and transfer characteristic of the TFT devices were tested. The best performance was obtained when Au was used to fabricate electrode, its saturation output current was 17.9 μA,and on-off current ratio was up to 1.4×106. In addition, the contact characteristics between three kinds of electrodes and IGZO thin film were analyzed based on their work function. Au electrode had the smallest contact resistance of these three metal according to the TLM(transmission line model) theory.关键词：IGZO;contact resistance;TLM theory;work function202|945|2更新时间：2020-08-12
- 摘要：The integration of the top-emitting organic light-emitting diode (OLED) driven by the organic thin film transistor (OTFT) was investigated. The OTFT operating voltage is decreased via reducing the thickness of the gate insulator layer. OLED adopts standard devices structure with green emission and employs the thin Al film as transparent cathode to realize top-emission. The integration of low-voltage operation OTFT and top-emitting OLED is achieved, while the threshold voltage of the OTFT is 2.0 V and the saturation field effect mobility is 0.40 cm2·V-1·s-1. Based on the experimental data, the electrical characteristic of the integrated pixel is calculated and analyzed. Under the control of gate voltage from -5 to -10 V, the linear gray-scale control can be realized within the range of pixel brightness from 50 to 250 cd/m2.关键词：organic thin film transistor;organic light-emitting diode;integrated pixel;gray level control136|84|2更新时间：2020-08-12
- 摘要：Supercontinuum generation in homemade tellurite microstructured fibers by using a homemade 1 560 nm femtosecond fiber laser as pump source was demonstrated. The effects of the pump power, the length of fiber, the nonlinear coefficient and group velocity dispersion on the supercontinuum generation were investigated in detail. By optimizing the fiber structure, we archived an all-fiber supercontinuum source covering the range from 1 300 to 2 200 nm.关键词：supercontinuum light source;tellurite microstructure fiber;femtosecond fiber lasers103|151|2更新时间：2020-08-12
- 摘要：Laser/visible dual-mode seeker used for precise guidance of missile was designed. In order to reduce the structure volume, RC complex structure of double-channel was used, which shared main mirror and secondary mirror together, and multiple-folding for light transforming was adopted. The focal length and field angle of the visible light path are 100 mm and 3° separately, which are designed for searching the initial goal of the larger region. The focal length and field angle of the laser light path are 300 mm and 0.6° separately, which are designed for confirmation of the final target guided by laser. The computer software was used to optimize the analysis of design. The total quality is less than 600 g. These characteristics of structure design make certain the thermal stability and structural reliability. The results of environmental tests show that the visible MTF is better than 0.3@50 lp/mm, satisfying the end requirements.关键词：laser;visible;dual-mode seeker;environmental test;MTF154|987|2更新时间：2020-08-12
- 摘要：An atmospheric argon plasma jet was obtained with a needle-plate dielectric barrier discharge system. The discharge gap was kept at 4 mm and the argon gas flow rate was 0.5 L/min. A test capacitor and a test resistance were connected in series in the circuit, and the discharge current and the transport charge were measured simultaneously. The average discharge power in a period of the applied voltage was calculated by Lissajous figure. The plasma jet was investigated spatially by optical emission spectroscopy, and the electron density was estimated by Stark broadening of Ar Ⅰ 696.54 nm. It is found that the discharge is asymmetric at different discharge phases, and more discharge current pulses are generated during the positive half cycle of the applied voltage. In addition, with the increasing of the applied voltage, the pulse number and the discharge power increase. Moreover, the plasma density is in an order of 1015 cm-3. With the increasing of the distance from the needle tip, the electron density of the plasma jet decreases from 2.94×1015 cm-3 to 2.28×1015 cm-3. The results show that the electric field plays an important role in the discharge current number and the spatial distribution of the electron density.关键词：discharge power;optical emission spectroscopy;electron density;dielectric barrier discharge114|74|1更新时间：2020-08-12
- 摘要：In order to solve the problem of cooling LED multi-chip LED module, an integrated heat pipe heat sink was designed and fabricated. Heat dissipation experiments were conducted to study effects on heat load, filling ratio and inclination angle on the thermal performance of the heat sink in nature convection. The results show that the efficient heat transfer of the heat pipe can reduce the thermal resistance of the heat sink effectively and the optimum filling ratio is 30% in this research. Inclination angle in the range of 0°-50° has little effect on heat transfer capability of heat pipe at lower heat load. When the angle reaches 75°, heat transfer of heat pipe and thermal resistance of heat sink are all subject to a significant deterioration. The time heat sink enters stable state is about 30 min and is not affected by the magnitude of the power. However, the heat sink works stably after 40 min when angle is 75°. Compared to traditional parallel plate fins and sunflower fins heat sink, the chip junction temperature with integrated heat pipe heat sink is smallest.关键词：LED;heat pipe;heat sink;thermal resistance;junction temperature116|142|4更新时间：2020-08-12
- 摘要：We have presented the theoretical method of extracting the optical functions from terahertz (THz) time-domain spectroscopy, which is based on optical transfer matrix. Compared with the conventional method of extracting main pulse, this method can be generalized to the cases that the main pulse and the subpulses can not be distinguished. Meanwhile, we have obtained the complex refractive indices of sapphire from 0.3 to 1.0 THz by the method of optical transfer matrix. Compared with the results from the method of extracting main pulse, the security and accuracy of the optical transfer matrix method are both tested and verified. The theory present in this paper provides a solid theoretical foundation for analyzing the THz time-domain spectroscopy of the cases that the main pulse and the subpulses can not be distinguished.关键词：terahertz time-domain spectroscopy;optical transfer matrix;complex refractive index120|202|3更新时间：2020-08-12
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