最新刊期
卷 36 ， 期 10 ， 2015
- 摘要：12CaO·7Al2O3:Ce3+ (C12A7:x%Ce3+) transparent ceramics were synthesized by a solid state method. Upon 350 nm UV excitation, a broad emission band located around 440 nm can be observed and it can be attributed to the transitions from 5d1 to 2F5/2 and 2F7/2 of Ce3+, respectively. It can be seen that the emitting intensity increases with the increasing of Ce3+ doping concentration. When the mole fraction of Ce3+ exceeds 0.7%, other impurities appear. To enhance the emitting intensity, C12A7:0.5%Ce3+ transparent ceramics were prepared by a self-propagating combustion method. For the samples annealed in H2 ambient, the scintillation properties, such as the emitting intensity and decay time, are improved by controlling sorts and amounts of encaged anions in C12A7. The experiment results show that Ce3+ doped C12A7 might be a potential scintillation material.关键词：12CaO·7Al2O3;Ce3+;scintillation properties;decay time;ceramics131|58|1更新时间：2020-08-12
- 摘要：High quality CdSe@ZnS and CdZnS/ZnS quantum dots (QDs) with core/shell structures were synthesized by the one pot method. The two types of QDs were mixed with the hole transport material CBP, respectively. The CBP:QDs hybrids were spin coated as the active layers. The green and blue emitting QD light-emitting diodes (LED) can be prepared with simple spin coating operation. This method reduces the steps of spin coating because the hybrid of CBP and QDs is spin coated together, thus the QD-LED can be produced easily. For the QD-LED with two spin coating steps, the energy level of cathode is far from that of CBP:QD layer, which results the high turn-on voltage. Surface states of QDs in CBP may capture the injected carriers to form the surface state emission. The surface state emission related to the carrier density.关键词：quantum dots;core-shell structure;LED;hole transport material;electroluminescence;surface state emission123|185|4更新时间：2020-08-12
- 摘要：Mn doped Zn-In-S quantum dots (QDs) were prepared and the effect of Zn/In molar ratio and reaction temperature on their photoluminescence properties were studied. A 600 nm photoluminescence band was observed in the doped QDs. The absorption band of the doped QDs could be tuned from 3.76 eV (330 nm) to 2.82 eV (440 nm) by changing the Zn/In ratio while the photoluminescence band around 600 nm only slightly shifted. The longest photoluminescence lifetime in the doped QDs reached up to 2.14 ms. When the reaction temperature increased to 230 ℃ from 200 ℃, the photoluminescence intensity of doped QDs increased and reached the maximum. When the temperature increased to 260 ℃, the photoluminescence intensity rapidly deceased. Further the temperature-dependent photoluminescence spectra of Mn doped Zn-In-S QDs were measured. It was found that the photoluminescence intensity significantly decreased, the photoluminescence peak slightly shifted to higher energy, and the linewidth of the photoluminescence increased with the increasing of temperature. It can be concluded that the emission in Mn doped Zn-In-S QDs originates from the radiative recombination of Mn2+ ions between 4T1 and 6A1 energy states.关键词：doped quantum dots;nanocrystals;Mn:Zn-In-S;photoluminescence lifetime;temperature-dependent photoluminescence126|116|4更新时间：2020-08-12
- 摘要：The water-soluble AgInS2 quantum dots/low molecular weight chitosan nanocomposites (AgInS2/LCSMS) were successfully synthesized. Natural polysaccharide in alkaline polysaccharide——Chitosan was used as stabilizer and capped agent. The structure, chemical composition, and optical properties of AgInS2/LCSMS nanocomposites were studied by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), fluorescence microscope, fluorescence spectrophotometer, and UV-Vis absorption spectroscopy, etc. The results show that the particle diameter of AgInS2/LCSMS nanocomposites is about 5-6 nm, and they are still have a relatively stable luminescence in the water phase. In addition, we studied the biological compatibility of the AgInS2/LCSMS nanocomposites. Compared with pure AgInS2 quantum dots, the cell activity of AgInS2/LCSMS nanocomposites has an obvious improvement. It shows that low molecular weight chitosan wrapping can obviously improve the biocompatibility of the nanometer materials. Therefore, this kind of AgInS2/LCSMS fluorescent nanocomposites with good water solubility and biological compatibility show significant value for potential applications in biomedicine test, biolabel, cell and in vivo imaging studies.关键词：low molecular weight chitosan;AgInS2 quantum dots;toxicity97|173|0更新时间：2020-08-12
- 摘要：Novel efficient blue phosphors Ba1-xKBP2O8:xEu2+ were successfully synthesized by high-temperature solid state reaction. The structure and luminescence properties were characterized systematically by XRD and fluorescence spectra, respectively. The results show that Eu2+ doping does not produce significant changes for the crystal structure which remains pure tetragonal. Excitation spectrum (monitoring wavelength is 443 nm) is composed of the acromion at 307 nm due to host absorption, and the main peak at 346 nm due to 4f7-4f65d transition Eu2+ ions. Under violet light excitation, the samples emit blue light. When the mole fraction of Eu2+ is 0.03, the emission spectrum has a maximum intensity. However, with further increase of the concentration of Eu2+, the emission spectrum intensity decreases, as a result of concentration quenching. At temperatures over 370 K, the intensity of the phosphors is still more than 50%. The CIE chromaticity coordinate of BaKBP2O8:Eu2+ is (0.176 6, 0.168 1).关键词：phosphors;BaKBP2O8:Eu;blue-emitting172|199|0更新时间：2020-08-12
- 摘要：A green-emitting phosphor, Ca8MgLu(PO4)7:Tb3+, was synthesized by a solid-state reaction. The photoluminescence excitation (PLE), emission (PL) spectra, and decay curves were measured to investigate photo-luminescent property of Tb3+ in Ca8MgLu(PO4)7 host. The excitation and emission spectra indicate that the phosphors can be effectively excited by the near ultraviolet (NUV) light (378 nm) and emit strong green emission of Tb3+ 5D4-7F5 transition. The CIE chromaticity (x, y) of Ca8MgLu(PO4)7:Tb3+ is (0.324, 0.592). The internal quantum efficiency of Ca8MgLu(PO4)7:Tb3+ is as high as 84% under the excitation of 378 nm. The phosphors show a good thermal stability at high temperature (200 ℃), and the emission intensity at 150 ℃ and 200 ℃ is 90.71% and 86.36% of that at 25 ℃. The results indicate that Ca8MgLu1-x(PO4)7:xTb3+ can be served as a potential green-emitting phosphor candidate for NUV LED application.关键词：phosphors;WLED;Ca8MgLu(PO4)7:Tb3+115|93|5更新时间：2020-08-12
- 摘要：A thiourea Schiff base (L) containing carbazole was synthesized from carbazole derivative and 4-phenyl-3-amino thiourea as reagents. The structure of compound L was characterized by 1H NMR and MS. The recognition performance and the binding mode of L and metal ions were investigated by UV-Vis and fluorescence spectroscopies. The results show that L has a quick visual selective recognition response to Hg2+ and Ag+. The addition of metal ions caused the color of L changed from colorless to yellow, and it can be identified by the naked eyes. The fluorescence spectrum of L has different changes with the adding of Hg2+ or Ag+ to the solution. The presence of other ions does not interfere with the selective recognition of L for Hg2+ and Ag+. It is also found that the binding model of L and Hg2+/Ag+ for fluorescent recognition is different: L coordinates with Ag+ to form complex which causes fluorescence quenching effect; L coordinates with Hg2+ to form complex which causes fluorescence quenching effect, then the complex removes HgS to produce a new compound.关键词：carbazole;thiourea;Schiff base;ions recognition138|87|3更新时间：2020-08-12
- 摘要：The multilayer structure of phosphorescent organic white light-emitting devices(WOLEDs)were fabricated, and the spectral stability was enhanced by adding hole-blocking layer (TPBi) in the light emitting layer. When the thickness of TPBi is 2.5 nm, the change of CIE coordinate is (0.031, 0.006) during the voltage changing from 8 to 12 V. In addition, the current efficiency is 24.7 cd/A, and the maximum external quantum efficiency is 8.2%. Compared with the device without hole-blocking layer, the CIE coordinate changes from (0.435, 0.472) to (0.333, 0.439) while the voltage is 8 V. The experiment results show that the CIE coordinate can be changed and the spectral stability can be enhanced by adding an interlayer in the light emitting layer.关键词：WOLEDs;hole-blocking layer;spectrum stability121|186|1更新时间：2020-08-12
- 摘要：A highly efficient blue phosphorescent organic light-emitting diode (OLED) with double emitting layer (DEL) structure was prepared using both 1,3-bis(carbazol-9-yl)benzene (mCP) and p-bis(triphenylsilyly) benzene (UGH2) as host material, and iridium(Ⅲ) bis[(4,6-difluo-rophenyl)-pyridinato-N,C2](FIrpic) as phosphorescent guest material. The physical mechanisms on the high efficiency were discussed. Compared to the device with single emitting layer using mCP or UGH2 as host material, the OLED with double emitting layer structure has higher efficiency. The maximum current efficiency, power efficiency, and external quantum efficiency of the device are 21.13 cd/A, 14.97 lm/W, and 10.56%, respectively. The efficiency roll-off between 100 cd/m2 and 3 000 cd/m2 is 34.2%.关键词：organic light-emitting diode;blue phosphorescent;double emitting layer148|137|1更新时间：2020-08-12
- 摘要：NaOH solution and HCl solution were used to recycle the used indium-tin oxide (ITO) substrate. The treated surface was then observed by using atomic force microscopy (AFM), while organic light-emitting devices (OLEDs) were fabricated with the recycled ITO to study the influence of reutilization on the performance of OLED. The results show that such treatments can efficiently remove the residual aluminum electrodes on the used ITO and change the chemical composition of the surface, especially by the NaOH treatment. OLED based on such recycled ITO can achieve a current efficiency of 12.08% with an increase of 14.7% compared with that based on new ITO, while the external quantum efficiency reached 5.23% with an increase of 11.7%. In addition, the sterically hindered between the chromophores and between chromophore and auxochrome increased, resulting in the enhanced side-band effect in the electroluminescence spectrum of the device when ITO was processed by different methods.关键词：indium-tin oxide;organic light emitting devices;reutilization117|195|0更新时间：2020-08-12
- 摘要：A novel transparent conducting oxide, PrTiO3-doped indium oxide (IPTO), is developed via double source reactive electron beam evaporation technology. The film exhibits a high work function of 5.14 eV and its stability is demonstrated in air for two months. The numerical values of optical and electrical properties of IPTO film and the commercial ITO are similar. Two OLEDs were fabricated by employing IPTO and ITO as anode, respectively. For device with IPTO anode, the peak luminance is 85 140 cd/m2 and maximum external quantum efficiency is 3.16%, which are 3 times and 1.13 times of the ITO device. It has been demonstrated that the improvements in device performance are achieved for the IPTO-anode OLED.关键词：transparent conductive oxide;work function;OLED111|128|2更新时间：2020-08-12
- 摘要：Employing MOCVD and CVD growth technique, the solar blind ultraviolet-near infrared dual-color detectors were successfully fabricated based on AlGaN with high Al component and single-layer graphene materials by vertical integration. The typical response of the dual color detectors in the ultraviolet band at 263 nm is 5.9 mA/W, and that in the near infrared band at 1.15 μm is 0.67 mA/W, under the operating condition of room temperature, the modulation frequency of 209 Hz, and the operating voltage of 10 V and 5 V, respectively. Besides, the responses of the two types of detectors will increase with the increase of operating voltage.关键词：AlGaN;graphene;UV-IR dual-color detector142|160|2更新时间：2020-08-12
- 摘要：High quality ZnO thin film was obtained on c-sapphire substrate by using a technique of plasma assisted molecular beam epitaxy (P-MBE), in which MgO and low temperature ZnO are used as buffer layers. High-resolution XRD measurement shows the full width at half maximum (FWHM) of (002) and (102) are only 68.4 and 1 150 arcsec, respectively. In the meantime, atomically smooth surface with root mean square (RMS) surface roughness of 0.842 nm is realized. In addition, Raman and photoluminescence (PL) measurements show that ZnO layer has extremely low stress level and defect density. The realization of high quality ZnO thin film pays a good way for the application of ZnO-based optoelectronic devices.关键词：buffer;stress;defects;ZnO;high quality thin film118|92|1更新时间：2020-08-12
- 摘要：GaN high electron mobility transistor (HEMT) has been widely acknowledged for use in high-frequency, high-power, and high-temperature applications because of their features such as its wide band gap, high electron saturation velocity, high 2-DEG density at the hetero-interface, high breakdown voltage (BV), and high thermal conductivity. The issues that limit the gallium nitride high electron mobility transistor device performance improvement and some solutions are introduced firstly. And then, the latest research progress on the high-frequency, high-power area of gallium nitride high electron mobility transistor is reviewed in detail with focus on the material structural design and the device structural design. Finally, the direction for the development of the device is discussed briefly.关键词：high electron mobility transistor;GaN;high-frequency;structural design172|976|4更新时间：2020-08-12
- 摘要：11 mini-bars with a width of 5.4 mm were coupled into a 200 μm/0.2 QBH fiber by beam shaping, spatial overlapping, polarization multiplexing, and wavelength multiplexing. The diode laser source with a continuous wavelength power of 386 W, a power density of 1.23 MW/cm2 and the electro-optical (E-O) efficiency of 43.6% at 50 A emitting from the fiber is developed. This laser source has been employed to directly cut the stainless sheet with the thickness of 1 mm at the output power of 200 W.关键词：diode laser;stainless sheet cutting;laser coupling;fiber coupled159|138|4更新时间：2020-08-12
- 摘要：An ionic wind cooling method based on corona discharge theory was presented to meet the thermal demand of high power LED. The electrical properties of corona discharge were studied through experimental measurement. The effect of discharge voltage on the refrigerating performance was researched, as well as the change laws of temperature drops with discharge power. The experimental results indicate that the negative corona can generate ionic wind at lower voltage and result in siganificant cooling at the same electrode gap comparing with positive corona.The corona current square root displays a good linear relationship to the applied voltage.The optimal refrigerating performance is attained at 1.5 W power and 10 mm electrode gap.关键词：high power LED;corona discharge;ionic wind;needle-mesh electrodes;forced heat transfer112|228|0更新时间：2020-08-12
- 摘要：In order to compute the natural illuminance, it is necessary to select one correctly among the 15 sky types defined by CIE to correspond to real sky. Firstly, according to the ratio of the sky illuminance on a vertical surface facing the sun to the sky illuminace on a vertical surface back the sun, the 15 sky types can be divided into 6 groups. Secondly, the 6 groups sky types can be further divided according to the ratio of the window sky light illuminance formed by the result on the two different measuring points in the space model. And ultimately, the correct type can be chosen from the 15 sky types of CIE standard general sky model. The result from the comparison between the selected sky type and the real sky type shows that this method works accurately on choosing the correct sky type for the real sky.关键词：atmospheric optics;selection of CIE sky types;calculation of illuminance;law of solid angle projection113|522|1更新时间：2020-08-12
- 摘要：Based on the theory of phase change decalescence of throttled cooling medium with high pressure in the micro evaporation cavity, a new pack module was designed for the refrigeration of high power laser diode. Oxygen-free copper with high heat-conducting was adopted in the module. The micro evaporative cooling module was constructed with the process of wire-electrode cutting, chemical corrosion, and welding by the newly designed welding equipment. According to thermal model of high power laser diode, numerical simulation is conducted theoretically on the module, and the result is consistent with the experiment of the heat dissipation of laser bar with the power of 60 W. From the experiment, the thermal resistance is 0.289 ℃/W when the refrigerant flow rate is 23 mL/min.关键词：micro-evaporation cavity;high power laser diode;heat sink115|86|1更新时间：2020-08-12
- 摘要：A finite element thermal analysis model of 5×5 AlGaInP-based LED microarray was established and simplified according to the calculation results. The results show that the simplified model and original model have the same temperature distribution, relative error of simplified model is 0.8% at 1.5 s. Using the simplified model, the temperature distribution of the chip with the size of 10 mm×10 mm×100 μm and 104 units was calculated, and the center temperature of chip reached 360.6 ℃ at 1.5 s. In order to solve the problem of heat dissipation, two finned radiators were designed, and the impacts of radiator structure, adhesive material, and number of fins on the temperature of chip were simulated.关键词：optical devices;thermal characteristic;finite element analysis;LED microarray;radiator127|207|1更新时间：2020-08-12
- 摘要：The optimal design of the particle number concentration of phosphor is an important way to improve the color quality and lumen efficiency of white LED. Through the method of optical simulation, the optical properties were analyzed under the influence of different particle number concentrations. According to the simulation results, with the increasing of the particle number concentration of phosphor, the absorption and scattering of blue light are strengthened. It is helpful to get the higher luminous efficiency, the better white light spot and uniform chrominance. When the particle number concentration of phosphor is at level of 105 /mm3, the LED light spot has the most uniform light intensity distribution and chrominance, and approximates the standard white light source.关键词：LED;optical simulation;phosphors;particle number concentration;luminous efficiency157|838|2更新时间：2020-08-12
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