最新刊期
卷 33 ， 期 8 ， 2012
- 摘要：High efficiency red phosphorescent organic light-emitting devices were fabricated based on multiple quantum well (MQW) structure. A type-Ⅱ MQW structure is formed by using 4,4'- bis(N-carbazolyl)-1,10-biphenyl(CBP)∶bis(1-phenyl-isoquinoline)(Acetylacetonato) iridium(Ⅲ) (Ir(piq)2(acac)) as the red emitting layer and 4,4'-bis(N-carbazolyl)-1,10-biphenyl (Bphen) as the charge control layer. The MQW device shows a maximum luminescence and current efficiency of 15 000 cd/m2 and 7.4 cd/A, respectively. The current efficiency of the MQW device is enhanced by 21% compared with the reference device. The improvement is attributed to the well confined of the holes and electrons in the MQWs and the balanced charge carrier injection, which results in an increased charge carrier recombination probability and enhances the efficiency.关键词：quantum well;phosphorescent;Ir(piq)2(acac);organic light-emitting devices87|108|1更新时间：2020-08-12
- 摘要：The optical phonons are investigated experimentally by means of Raman scatterning and by the modified random element isodisplacement (MREI) model in hexagonal quaternary nitride-based crystals. A one-mode behavior of E1 and A1 branches is presented in our calculated results. The calculated A1(LO) branches are almost consistent with our experimental data for InxGa0.45-xAl0.55N crystals, and Cros's experimenatal results for InxAl0.42-xGa0.58N crystals.关键词：InAlGaN;optical phonon;Raman scattering;MREI76|65|4更新时间：2020-08-12
- 摘要：The Raman spectra of CCl4 diluted with C6H6 at different volume fractions have been measured. We have calculated the v1+v4~v3 Fermi resonance parameters of CCl4 in C6H6 at different volume fractions according to the Bertran equations. It turns out to be that with the decreasing concentration of CCl4, the ratio of intensities of Fermi doublets, R increase, while all the other Fermi resonance parameters decrease. This phenomenon can be accounted for the solvent effect. The Raman scattering coefficients of CCl4 in C6H6 decrease with the CCl4 volume fraction, which can be attributed to the enhancement of the v1+v4~v3 Fermi resonance of CCl4.关键词：Fermi resonance;Raman spectroscopy;solvent effect83|117|1更新时间：2020-08-12
- 摘要：A series of Ba2SiO4∶Eu2+ green phosphors have been synthesized by high temperature solid state method. The effects of different fluxes on the crystal structure, surface morphology and spectral characteristics of Ba2SiO4∶Eu2+ phosphors were systematically investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrophotometer. The function mechanism of different fluxes on the preparation of Ba2SiO4∶Eu2+ phosphors have also been discussed. XRD results show that the Ba2SiO4∶Eu2+ phosphor without flux has the impurity phase of BaSi2 and SiO2 during firing, while fritted with NH4F, Na2CO3 or H3BO3 flux, the impurity phase of BaSi2 can be suppressed. BaF2 flux can get the pure orthorhombic. By comparing the influence of different fluxes on the emission of Eu2+, it was found that the emission intensity of the Ba2SiO4∶Eu2+ phosphor with 2% mass fraction of BaF2, NH4F or Na2CO3 flux improved by 138%, 81%, 34% than that of the powder without the flux material, while the luminescent intensity reduced 14% when using 2% mass fraction of H3BO3 as flux. The phosphor powders were spherical-like shapes using BaF2 as the flux, while the phosphor powder prepared with NH4F, Na2CO3 or H3BO3 as flux had the irregular laminated structure, spindle shape and irregular polygon, respectively.关键词：Ba2SiO4∶Eu2+;solid-state method;flux;phosphor121|100|4更新时间：2020-08-12
- 摘要：Blue luminescent Sr2MgSi2O7∶Eu2+,xBi3+ (x=0,0.02,0.04,0.06,0.08,0.1) powder phosphors have been successfully synthesized by sol-gel method. Their structure and luminescent properties were analyzed by XRD, DTA-TG, and PL spectra. Emission spectra of Sr2MgSi2O7∶Bi3+ powder phosphors with λex=286 nm (3P1→1S0) and Sr2MgSi2O7∶Eu2+,xBi3+ (x=0, 0.02, 0.04, 0.06, 0.08,0.1) phosphors with λex=358 nm (4f65d1→4f7) have been analyzed. Based on the emission performance of Sr2MgSi2O7∶Eu2+,xBi3+, the optimized Bi3+ mole fraction is 0.04. The luminescent intensity of the phosphor increases up to 1.9 times than that of phosphors without doping Bi3+, which due to the sensitization of Bi3+ to Eu2+.关键词：Bi3+;Sr2MgSi2O7;sol-gel method;blue luminescence130|59|0更新时间：2020-08-12
- 摘要：Red Bi4Ge3O12(BGO) single crystals had been grown by vertical Bridgman (VB) method. The luminescence and decay time in the near infrared (NIR) region were measured at temperature of 8 K. A broad emission band was found at around 1 150 nm at T< 200 K, and the luminescence lifetime was measured to be several hundred microseconds. The decreased temperature led to increased luminescence intensity.关键词：red Bi4Ge3O12;low temperature;luminescence100|45|0更新时间：2020-08-12
- 摘要：Two novel rare earth ( Eu, Tb) binary complexes with 3,3',4,4'-Biphenyl tetracarboxylic as the ligand were synthesized and characterized by elemental analysis, FT-IR, TG-DTG. The compositions of the complexes were found to be Tb5L3(OH)3·8H2O and Eu5L3(OH)3·10H2O (L=BPDA). There are two coordination modes of the carboxylate ligands in the complexes. Most of them are in bridging mode with BPDA linked to two rare earth ions, the others are in chelating mode with BPDA chelated to the same rare earth ion. These novel rare earth complexes have good thermal stability. Their photophysical properties were further investigated by UV absorption spectra and fluorescence spectra. The results indicate that both of the terbium and europium complexes exhibit red fluorescence. The fluorescence lifetime of the 5D4→7F3 transition (613 nm) for Tb(Ⅲ) complex is 491.1 μs,which is longer than that of the 5D4→7F5 transition (544 nm,27.9 μs). The fluorescence lifetime of the 5D0→7F2 transition (613 nm) for Eu(Ⅲ) complex is 329.5 μs. The fluorescence quantum yield of Eu(Ⅲ) complex is 13.05%.关键词：3;3';4;4'-Biphenyl tetracarboxylic dianhydride;rare earth (Eu or Tb) complexes;red fluorescence84|137|1更新时间：2020-08-12
- 摘要：Red-light-emitting phosphors of Pr3+ activated Ca1-xPrxMoO4 were synthesized by high temperature solid state reaction. The luminescence spectra of samples indicate that under the excitation of 453 nm, all samples produce red emission peak at 654 nm corresponding to the characteristic transition of Pr3+ (3P0→3F2). The influence of Pr3+ doping mole fraction (x) on the luminescent intensity of samples was analyzed. The optimum doping mole fraction of Pr3+ was x=0.01. In order to further improve the luminescent efficiency, two charge compensation approaches were applied: (1) two Ca2+ ions were replaced by one Pr3+ ion and one M+ (M=Li, Na) ion and (2) three Ca2+ ions were replaced by two Pr3+ ions. It is found that both charge compensation approaches can obviously improve the red luminescent intensity. In particular the relative emission intensity of Ca0.98Pr0.01Li0.01MoO4 reached more than 3.17-fold as compared with that of the sample without the charge compensation.关键词：Ca2MoO4;Pr3+ ion;luminescence;charge compensation103|88|2更新时间：2020-08-12
- 摘要：KCaY(PO4)2∶Tb3+ phosphor was synthesized by the hydrothermal method and characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD patterns demonstrated that the synthetic material belonged to the phase of KCaY(PO4)2 crystal without detectable impurity. The SEM image showed that the morphology of the product was completely in the form of quadrangular and prismhexagonal prisms. Under the excitation of ultraviolet (218 nm), the emission spectra exhibited multi emission peaks from blue to red. Tunable emission from the greenish-blue to yellowish-green region was achieved by changing concentration of Tb3+. In order to obtain white light emission, Eu3+ was introduced into KCaY(PO4)2∶Tb3+ host. A low color temperature white light was achieved by an effective energy transfer from Tb3+ to Eu3+. KCaY(PO4)2∶Tb3+, Eu3+ can be used as a potential single-phased white phosphor excited by ultraviolet or vacuum ultraviolet.关键词：hydrothermal;cross-relaxation;energy transfer;white light emitting139|319|1更新时间：2020-08-12
- 摘要：The red phosphor powders BaWO4∶16%Eu3+ were successfully prepared by hydrothermal method in different hydrothermal time. The crystal structure and surface morphology of the phosphor as-prepared was characterized by XRD patterns and SEM, respectively. The correlation between the crystal orientation of the matrix and the characteristic emission of the doped rare earth ions Eu3+ were discussed. The pure phase structure BaWO4∶16%Eu3+ phosphor was obtained under the hydrothermal reaction at 160 ℃. The room temperature characteristic emission 5D0→7F0 and 5D0→7FJ(J=1, 2)of Eu3+ ions in the samples as-prepared were observed under the excitation of 395 nm or 464 nm light. 5D0→7F2 transition emission intensity was significantly higher than those of 5D0→7F1 and 5D0→7F0. XRD analysis indicates that the samples prepared at a hydrothermal temperature of 160 ℃ are all tetragonal. The growth rates of each crystal face vary with different hydrothermal time. This difference leads to a change of crystal symmetry and the luminescent properties of BaWO4∶Eu3+ samples. The optimized hydrothermal time is 10 h for the Eu3+ doping concentration of 16%.关键词：hydrothermal method;BaWO4∶Eu3+;nano-phosphor;luminescene92|136|4更新时间：2020-08-12
- 摘要：A blending crystalline system containing poly(3-hexylthiophene) and polycaprolactone was investigated. The electric measurements reveal that the field-effect performances of blend films, such as mobility, on/off current ratio and threshold voltage, decrease slowly with P3HT content reducing. However, the devices still have relatively good performance even P3HT content was 40%. According to the AFM studies, vertical phase separation occurs in the blend films, and a connective semiconducting layer can be observed in the interface between insulating layer and active layer, which is beneficial to transport of charge carriers.关键词：organic thin-film transistors (OTFTs);semiconducting/insulating blend;phase separation;electric performance115|110|3更新时间：2020-08-12
- 摘要：The distribution temperature of the integrating sphere was calculated according to the measured integrating sphere spectral distribution. The influence of integrating sphere source's distribution temperature on broadband optical remote sensor's absolute calibration accuracy is analyzed. The simulation experiment was carried out to calculate optical remote sensor's absolute calibration coefficient based on different distribution temperature sources, including the measured integrating sphere source and the sun. The calculation result indicated that the maximum calibration coefficient difference between different distribution temperature sources was over 2%. The correcting methods to reduce the influence of integrating sphere source's distribution temperature on broadband optical remote sensor's absolute calibration accuracy are proposed, which will provide effective method for improving radiometric calibration accuracy and calibrating remote sensing image.关键词：optical remote sensor;radiometric calibration;integrating sphere;distribution temperature120|185|9更新时间：2020-08-12
- 摘要：The influence of different energy electron beam irradiation on the luminescence properties of GaN-based LED has been studied. GaN-based LED epitaxial wafers are irradiated under the simulation of space electron radiation by 1.5, 3.0, 4.5 MeV electron beam irradiation in the laboratory and photoluminescence (PL) spectra is applied to measure luminescent properties. The results show that LED luminous intensity increase about 25% when the radiation doses is 10 kGy with electron energy is 1.5 MeV, while reduced ~16% in dose irradiation in 100 kGy. Under 3 MeV electron beam irradiation, the color purity of LED increased, while in the higher energy irradiation the device failed.关键词：electron-beam irradiation;LED;luminescent properties;GaN91|154|4更新时间：2020-08-12
- 摘要：The spectra of the bi-color and tri-color phosphor-converted white LED were optimized in the neutral correlated color temperature of 4 870 K with consideration of Stokes shift energy loss. The results showed that a high luminous efficacy of radiation up to 483 lm/W could be attained in the case of the white LED composed of blue chip and YAG phosphor but with a poor color quality and 83.9% Stokes efficiency. When a narrow-band red phosphor or LED chip was added to the bi-color white LED, a good color rendering index of 94.7 was gained with a reduced luminous efficacy of radiation 343 lm/W and a Stokes efficiency of 84.4%. Later, we characterized the performance of tunable-color-temperature tri-color white LED. It was found that the color rendering index was better when the correlated color temperature exceeded 4 000 K.关键词：spectroscopy;spectrum optimization;correlated color temperature;color rendering index;luminous efficacy of radiation115|530|4更新时间：2020-08-12
- 摘要：The a-AlGaN Metal-semiconductor-Metal (MSM)ultraviolet photodetector (UV-PD) was fabricated, and the effect of SiO2 nanoparticles (SNPs) on its properties was investigated. It was shown that the dark current of the UV-PD with SNPs was more than one order of magnitude lower than that of without SNPs. The peak responsivity was enhanced more than two orders of magnitude after deposition of the SNPs. The SNPs on a-AlGaN MSM UV-PDs usually formed at the termination of screw and mixed dislocations, which acts a role of passivating the carrier transport paths. Surface-deposited SNPs make photogenerated electrons and holes collected easily in two separated contacts, which lead to a higher device property.关键词：SiO2 nanoparticles;a-plane AlGaN;MSM ultraviolet photodetectors105|111|0更新时间：2020-08-12
- 摘要：The photonic band gaps of two dimensional square lattice photonic crystals are analyzed in terahertz range using the plane wave expansion method and the finite difference time domain method. The simulation results indicate that the photonic gaps vary with the dielectric constants and radius of materials in the square lattice photonic crystal. Then the band gaps and transmitting characteristics of photonic crystal that based on the plastic and high-resistivity silicon are studied.关键词：terahertz wave;photonic crystal;plane wave expansion method;FDTD128|230|2更新时间：2020-08-12
- 摘要：The effects of electrodes on the optical performance of bilayer heterojunction organic solar cells have been investigated by employing MATLAB and transfer matrix method. The simulations reveal that the absorption of active layer is mainly influenced by phase shift of reflection in top electrode but not the transmittivity when microcavity structure is introduced into bilayer heterojunction organic solar cells. A significant improvement of light absorption has been achieved due to the optical resonance effect by adjusting the thickness of top capping layer. Furthermore, the simulations demonstrate that both reflectivity and reflection phase shift of back electrode play important roles in active layer optical absorption when one-dimensional photon-crystals(1DPCs) composed of positive and negative refractive index materials are introduced into bilayer heterojunction organic solar cells. The optical absorption in new device can be enhanced at a broad wavelength range comparing to traditional device by adjusting the thickness of back electrode when the period of 1DPCs is 10.关键词：bilayer heterojunction organic solar cells;optical absorption;transfer matrix method;electrode90|81|1更新时间：2020-08-12
- 摘要：A high power fiber-coupled flexible source is fabracated in which 20 conduction cooled diode laser bars were intergrated in manner of linear array coupling. Under the macrochannel cooling with industrial water, a CW output power of 907 W, a beam parameter product of 47 mm·mrad, an optical power density of 3.21×105 W/cm2 and a maximum wall-plug efficiency of 39% on the work piece are demonstrated from a 600 μm, NA 0.2 fiber. This source has a great potential to be directly adapted in materials processing, especially in metal sheet welding.关键词：diode laser;linear array coupling;fiber-coupled;flexible processing source106|100|4更新时间：2020-08-12
- 摘要：We proposed a PT-symmetric metal-insulator-metal waveguide system, in which two waveguides coupled to a ring resonator, one arm of ring resonator was filled with gain medium, the other arm with loss medium. The transmission character of the system was studied. The results showed that, through balancing of gain and loss medium, PT-symmetry induced transparency can be clearly seen, which indicated the transmission peak have an opposite phases.关键词：metal-insulator-metal waveguide;PT-symmetry;PT-symmetry induced transparency122|100|4更新时间：2020-08-12
- 摘要：Succinic-oligochitosan-Eu(Ⅲ) complex was synthesized and characterized. Under simulated physiological conditions, the interaction between complex and bovine serum albumins (BSA) was studied by ultraviolet spectrum and fluorescence spectrum. The results showed that the absorption intensity of BSA increased with the concentration of complex. The complex quenched the fluorescence of BSA and it was static quenching, and then the binding constant and binding sites were calculated . They were 2.068 2×104 L·mol-1 and 1.094 72 at room temperature, respectively.关键词：succinic-oligochitosan-Eu(Ⅲ);bovine serum albumin;interaction86|99|3更新时间：2020-08-12
- 摘要：The water-soluble CdTe was synthesized using thioglycolic acid as stabilizer. The fluorescence resonance energy transfer (FRET) between the CdTe QDs and Rhodamine B (RhB) in the presence of cetyltrimethylammonium bromide (CTAB) was characterized, in which the QDs with an emission wavelength of 530 nm was used as energy donor and rhodamine B as acceptor. Lysozyme content in lysozyme buccal tablets was determined by fluorescence resonance energy transfer. The results showed that the extent of fluorescence energy transfer quenching was linearly proportional to the concentration of lysozyme from 2?10-7 mol稬-1 to 8?10-6 mol稬-1 with a correlation coefficient of 0.991 0. The minimum detection concentration was 2?10-8 mol稬-1, RSD and the average recovery was 5.8% and 101%(n=5), respectively.关键词：CdTe;RhB;FRET;lysozyme116|94|2更新时间：2020-08-12
- Address：No.3888 Dong Nanhu Road, Changchun, Jilin, China Postal code：130033
- Tel：0431-86176862 Email：fgxbt@126.com
- Technical support is provided by Beijing Founder electronics co., LTD 吉ICP备11002662号-17
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0