最新刊期
卷 34 ， 期 6 ， 2013
- 摘要：Hybrid inorganic/organic white organic light emitting diodes (hybrid-WOLEDs) are fabricated by combining the blue phosphorescent organic light emitting diodes (PHOLEDs) with red Sr2SiO4:Eu3+ phosphor spin coated as a color conversion layer (CCL) over the other side of glass substrate on the devices. The basic configuration of the PHOLEDs consists a host material, N, N'-dicarbazolyl-3, 5-benzene (mCP) which doped with a blue phosphorescent iridium complexes iridium(Ⅲ)bis[(4,6-di-fluorophenyl)-pyridinato-N-C2'](FIrpic) to produce high efficient blue organic light emitting diodes. The hybrid-WOLED shows maximum luminous efficiency of 22.1 cd/A, maximum power efficiency of 11.26 lm/W, external quantum efficiency of 10.2% and CIE coordinates of (0.32, 0.34). Moreover, the output spectra and CIE coordinates of the hybrid-WOLED have a small shift in different driving current density, which demonstrate good color stability.关键词：white organic light emitting diodes(WOLEDs);color conversion layer(CCL);Sr2SiO4∶Eu;color stability105|121|0更新时间：2020-08-12
- 摘要：Water-soluble ZnSe:Cu quantum dots were synthesised in aqueous solution, ZnSe:Cu/CdS core/shell quantum dots(QDs)with different shell thickness were obtained in this paper. The influence of shell thickness on the optical properties of ZnSe:Cu QDs was studied. The samples were characterized by TEM, XRD, PL and UV-Vis. The results showed that ZnSe:Cu/CdS core/shell QDs have a cubic zinc-blende structure and are spherical with good dispersibility. The average grain size increased from 2.7 to 4.0 nm after the shell modification. The redshift of core/shell QDs compared with the core QDs was observed in both the UV-Vis and the PL spectra, which suggested that the size of core/shell QDs increased. The results proved that CdS shell were coated on the surface of ZnSe:Cu QDs and formed the ZnSe:Cu/CdS core/shell structure QDs. The PL intensity of the ZnSe:Cu QDs decreased with higher stability after being coated by CdS shell.关键词：quantum dots(QDs);ZnSe∶Cu;ZnSe∶Cu/CdS;core/shell structure130|168|2更新时间：2020-08-12
- 摘要：Cathodoluminescence behavior vs. accelerating voltage of electron beam in ZnO/ZnMgO multi-quantum wells was reported in this paper. The samples were grown on sapphire substrate by plasma-assisted molecular beam epitaxy. By exciton tunneling, the excitation efficiency was improved significantly. In a sample with asymmetric double-quantum-wells, a marked reduction of the optimal acceleration voltage from 7 kV to 5 kV was obtained compared to the symmetrical multi-quantum well sample.关键词：ZnO;quantum wells;electron beam pumped;exciton tunneling112|166|0更新时间：2020-08-12
- 摘要：An improved Pechini method was applied to synthesize YAG phosphor. Yttrium nitrate, cerium nitrate and aluminium nitrate were used as raw materials with ammonium citrate as complexing reagent and polyacrylamide as polymerizer. The YAG phosphor was analyzed by TG-DSC, XRD and SEM. The results showed that the phosphors synthesized by improved Pechini method had better crystallinity at lower calcining temperature compared with commercial advanced products. The illumination performance of pc-LEDs coated with the synthesized YAG phosphor were measured. The results show that the luminous efficiency of the synthesized YAG phosphor is 90.1% of the commercial advanced phosphor.关键词：WLED;YAG phosphor;improved Pechini method111|180|2更新时间：2020-08-12
- 摘要：The Ho3+-doped LiYF4 single crystals were grown by Bridgman method. The axial and transverse absorption spectra of Ho3+ ions in LiYF4 crystals were measured. The Judd-Ofelt theory was applied to calculate the J-O effective intensity parameters Ω2,4,6, spontaneous radiative transition rate, branching ratio, radiative lifetime of σ transition and π transition. IR emission spectra of Ho3+:LiYF4 single crystals were measured under 640 nm wavelength excitation, and the emission band around 2.9, 1.2 and 2.0 μm due to 5I6→5I7, 5I6→5I8,5I7→5I8 transition were observed. Based on the absorption spectra, the maximum calculated emission cross section emission at 1.2 and 2.05 μm in LiYF4:Ho3+ crystal are 0.20×10-20 and 0.51×10-20 cm2, respectively. In the meantime, the emission lifetimes at 1 191 nm (5I6→5I8) and 2 059 nm (5I7→5I8) were determined to be 2.13 and 17.23 ms. The research results indicate that Ho3+:LiYF4 crystal is a good candidate for mid-infrared laser media.关键词：polarized absorption spectra;Ho3+∶LiYF4 single crystal;mid-infrared luminescence;Jodd-Ofelt theory144|235|4更新时间：2020-08-12
- 摘要：ZnO:Mn thin films were prepared on glass substrates using RF magnetron sputtering method. Raman spectroscopy, X-ray diffraction spectra and SEM were used to analyze the structural characteristics of ZnO:Mn films with the different working pressure. The results show that ZnO:Mn thin films have the significant wurtzite structure with the different working pressure. The leftshifts of the Raman peaks corresponding to E2(High) mode and related to Mn doping are explained by the appearance of much more lattice defects and disorder in ZnO:Mn films with decreasing working pressure, which are also evidenced by XRD and SEM results.关键词：ZnO∶Mn;Raman;diluted magnetic semiconductors95|183|1更新时间：2020-08-12
- 摘要：The beta-gallium-oxide (β-Ga2O3) nano-material was prepared from gallium and oxygen by thermal evaporation in the argon atmosphere. The X-ray diffraction (XRD) reveals that the synthesized products are monoclinic gallium oxide. When the sizes of Au catalysts are small, the breadths of the nanowires are less than 100 nm and the lengths are several micrometers. With the increasing of the catalyst particle sizes, the morphology of the products are gradually transformed into nanobelts, sheets and other shapes. β-Ga2O3 has stable emission at 516 nm under excitation of 325 nm. With the increasing of the catalyst particle sizes, the luminescence intensity and the red-shift are gradually weakened.关键词：gallium-oxide;catalyst;nanostructure;photoluminescence;red-shift156|27|2更新时间：2020-08-12
- 摘要：Highly oriented γ-CuI thin films have been successfully prepared on indium doped tin oxide (ITO) glass substrate by a simple electrochemical process at different temperatures. For comparison, CuI powders are also obtained by a simple complex compound method. Analyses on phases and structures based on X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques indicate that the films are composed of CuI triangular facet nanocrystals with (111) preferred growth orientation, and decrease from 2 μm to 500 nm with increase of the deposition temperature. Furthermore, photoluminescence (PL) spectroscopic analysis shows a strong near band edge emission. It is also found that the CuI powders show some diverse in structural, morphology and optical properties compared with the CuI thin films.关键词：CuI thin films;temperature;structure;photoluminescence122|147|0更新时间：2020-08-12
- 摘要：In order to study the interface formation in the growth process of Ti-Si-N films, a series of calculations have been carried out with the first principle method to investigate the total energies and adsorption energies of some 3N1Ti1Si island configurations on the TiN (001) surface, and also the activation energies of two kinds of transformations from the Si-in-3N1Ti configuration to the Ti-in-3N1Si configuration. The calculations present some interesting results:(1) According to the energies of all 3N1Ti1Si configurations, the Ti-in-3N1Si configuration is a relative stable structure. It implies that silicon atom outside of TiN island could lead to the structure stable. (2) In the island evolution from the Si-in-3N1Ti configuration to the Ti-in-3N1Si configuration, the diffusion of silicon and titanium atoms need less activation energy than the diffusion of nitrogen atoms. (3) Compared with the evolution of 2Ti2N1Si island, the phase separation of SiN and TiN could be easily performed in the evolution of 3N1Ti-1Si island. This means that properly increasing the partial pressure of nitrogen in the deposition is beneficial to the interface formation in Ti-Si-N film growth process.关键词：interface formation condition;phase separation;configuration evolution;diffusion energy;first-principles93|176|0更新时间：2020-08-12
- 摘要：Temperature dependent characteristics of upconversion luminescence in β-NaYF4:Yb3+,Er3+ nanoplates under 980 nm excitation were reported. Intense green and red upconversion emissions corresponding to (2H11/2, 4S3/2) → 4I15/2 and 4F9/2 → 4I15/2 transitions of the Er3+ ions were observed, respectively. The green emission around 520 nm and the red emission around 660 nm continuously increase with increasing of temperature. The emission around 545 nm increases from 84 to 204 K and then decreases from 204 to 483 K. The temperature dependen ce of intensity characteristics was systematically analyzed by a simple three-level system.关键词：upconversion;β-NaYF4;rare earth;temperature-dependent;three-level system109|27|0更新时间：2020-08-12
- 摘要：LuVO4:Eu3+ nano-(or submicron-) phosphors have been prepared by hydrothermal method without (or with) further heat treatment. The properties of the resulting phosphors are characterized by X-ray diffraction, scanning electron microscope, photoluminescence spectra and decay curve. The excitation spectra of LuVO4:Eu3+ phosphors are mainly attributed to Eu→O charge-transfer band at about 275 nm as well as some sharp lines of Eu3+ f-f transitions in near-UV and visible regions with two strong peaks at 395 and 466 nm, respectively. Under the 275 nm excitation, intense red emission peak at 619 nm corresponding to 5D0→7F2 transition of Eu3+ is observed for LuVO4:8%Eu3+ phosphors as the optimal doping mole fraction. The luminescence properties suggest that LuVO4:Eu3+ phosphor may be applied as a potential red phosphor candidate for lighting and displays.关键词：optical materials;LuVO4∶Eu3+;hydrothermal method;luminescence94|118|1更新时间：2020-08-12
- 摘要：The green light emitting diode (LED) with an insertion layer between the multiple quantum wells and n-GaN layer was grown on c-plane sapphire substrate by metal organic chemical vapor deposition. The structural and optical properties of the LEDs with and without insertion layer were investigated. It is found that the insertion layer can promote the combination of In concentration, and induce an overall red-shift of wavelength. We speculate that the In phase separation and piezoelectric field would be responsible for the wavelength red-shift, the performance of LED deteriorated either.关键词：LED;phase separation;insertion layer149|116|1更新时间：2020-08-12
- 摘要：By using typical luminescent materials, 4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl (DPVBi) and 5,6,11,12-tetraphenylnaphthacene (Rubrene) as a blue and orange emitter, respectively, a highly efficient bright nondoped white electroluminescent device with low driving voltage and ideal chromaticity is fabricated. The turn-on voltage, maximum current efficiency are 3.1 V, 6.7 cd/A (luminous efficacy of 5.5 lm/W, external quantum efficiency of 2.8%), respectively. Commission Internationale de l'Eclairage (CIE) co-ordinates are at ideal equal-energy white point (0.33, 0.33). The achievement of excellent white emission is attributed to realizing perfect ratio of energy transfer from DPVBi to Rubrene by tuning distance from NPB/DPVBi interface to Rubrene.关键词：luminescence;organic electroluminescence;white;distyrylarylene derivative DPVBi;Rubrene138|162|0更新时间：2020-08-12
- 摘要：The front-surface and the bottom of amorphous silicon(a-Si) thin-film solar cell are designed respectively. Light absorption is calculated by using the rigorous coupled wave analysis(RCWA). In TM polarization, the absorption of solar cells with optimized AR coating can be increased by an average of 35% compared with that without AR coating in the range of 300~840 nm. Furthermore, the absorption of solar cells with optimized back reflector can be increased by an average of 23% compared with that without back reflector in the range of 700~840 nm. The amorphous silicon(a-Si) thin-film solar cell that we design has broadband and omnidirectional absorption, so that it can improve the conversion efficiency of solar cells.关键词：antireflection coatings;diffraction gratings;photonic crystals;absorption;solar cells104|131|1更新时间：2020-08-12
- 摘要：A layer of porous silicon was formed on the surface of the pyramids on the silicon using the electrochemical method. The effect of the porous silicon on the reflectivity of surface as well as the photovoltaic conversion quantum efficiency and the effect of oxidation on the photovoltaic conversion quantum efficiency for different wavelengths were studied. It was observed that the density of hydrofluoric acid(HF) did not make a difference on the reflectivity of the surface, and the electrochemical etching time can determine the minimun-reflection wavelength. The average reflectivity of the structure can be 2%. Because of the porous silicon,the photovoltaic conversion quantum efficiency is decreased for the wavelength between 300~500 nm, and is increased for the wavelength beyond 500 nm. Rapid oxidation can decrease the surface recombination so as to increase the photovoltaic conversion quantum efficiency for the short wavelength, and it can be a guidance for increasing the efficiency of the silicon solar cells.关键词：solar cells;porous silicon;pyramids;photovoltaic conversion quantum efficiency101|264|1更新时间：2020-08-12
- 摘要：Two types of organic light-emitting devices were fabricated using a spin-coated N,N'-di(naphth-1-yl)-N,N'-diphenyl-benzidine (NPBSC) film as hole-transport layer (HTL): ITO/NPBSC/Alq3/LiF/Al,ITO/NPBSC/NPB/Alq3/LiF/Al. The effect of air contaminated NPBSC/organic interface on the stability of organic light-emitting devices was investigated. It is found that the device using a NPBSC film as HTL exhibited the poorer stability, which is attributed to the instability of NPBSC/Alq3 interface that contaminated by moisture and oxygen from the NPBSC layer. A vacuum-deposited NPB film (10 nm) inserted between NPBSC layer and Alq3 layer can greatly improve the stability of device by blocking the recombination zone from contamination of moisture and oxygen.关键词：organic light-emitting devices;organic/organic interface;stability119|154|0更新时间：2020-08-12
- 摘要：A design is proposed to significantly increase the absorption of gallium arsenide thin-film layer. This is achieved by patterning a grating in the layer. By using rigorous coupled wave method, the absorption efficiency in the range of 300~900 nm has been analyzed for GaAs layer with rectangular and triangle gratings. The results show that the absorption efficiency of the two structures can be improved relative to the flat absorption layer and the peak absorption rate can be increased by 55.9%. And the structural parameters of the two structures have been also optimized. By analyzing the incident angular dependence of the two structures, it is concluded that solar cells with the triangular absorption layer have better characteristics in the same condition of thickness and filling factor. On the other hand, the finite element method is used to calculate the field distribution for different absorption layers. Good absorption enhancement can be observed directly from the absorption layer with gratings. The research provides a reference for the preparation of solar cell structures with high performance.关键词：GaAs;absorption layer;grating;absorption123|257|2更新时间：2020-08-12
- 摘要：AlN buffer and GaN epitaxial layer were prepared by MOCVD on Si(111) substrate. The effect of H2 carrier gas flow for AlN buffer epitaxy on GaN was investigated by high resolution X-ray diffraction, ellipsometer and atomic force microscope. It is found that AlN thickness increases (i.e. the increasing of AlN growth rate) with the increasing of H2 flow. The surface roughness of AlN also tends to increase. The change in surface roughness is attributed to the enhancement of island-growth mode. The increasing of AlN buffer thickness contributes to the increasing of tensile stress which promotes AlN island growth mode. The higher density of islands with bad orientation was observed by AFM on AlN buffer layer which was grown with higher H2 flow. ω scan of (0002) and (101 2) show that the increasing of H2 flow leads to the increasing in FWHM of GaN(i.e. the increasing in density of screw threading dislocation and edge threading dislocation). Because the three-dimensional growth of GaN starts on the top of AlN islands, the AlN buffer layer with high density of islands contributes to rapid coalescence of GaN islands that will lead high density of edge threading dislocation. The bad orientation of AlN islands on buffer layer will lead to GaN thin film with high density of screw threading dislocation. The obtained data demonstrate that the H2 carrier gas flow plays an important role in improving the crystal quality of GaN.关键词：GaN;AlN buffer;H2 carrier gas;Si substrate;MOCVD168|85|1更新时间：2020-08-12
- 摘要：Multi-walled carbon nanotube solution was prepared by using sodium dodecyl sulfonate(SDS) and poly(3,4-ethylenedioxythiophene) polymerized with poly(styrenesulfonate)(PEDOT/PSS) as dispersers. Polydimethylsiloxane(PDMS) was used to make the silicon wafer hydrophilic or hydrophobic. Carbon nanotube thin film electrode can be made using drop-casting method on the patterned silicon wafer. The patterned electrode was used in the organic thin film transistors. The filed-effect mobility of the devices using SDS and PEDOT/PSS as dispersers are 0.01 cm2·V-1·s-1 and 0.007 5 cm2·V-1·s-1, respectively, both the Ion:Ioff ratio are 3×103.关键词：multi-walled carbon nanotube;solution based fabrication;organic thin film transistors(OTFT);electrode;pattern92|135|0更新时间：2020-08-12
- 摘要：A high brightness 808 nm edge-emitting diode laser based on the dual-sided Bragg reflection waveguide was reported. The 10 μm-wide ridge lasers with uncoated facets demonstrated more than 650 mW power in quasi-continuous-wave operation, being limited by the thermal rollover of the unmounted devices. A nearly circular output beam is obtained due to the significantly expanded modal spot size. The beam divergence with full-width at half maximum was as narrow as 8.3° and 8.1° respectively in the vertical and lateral directions.关键词：diode laser;Bragg reflection waveguide;low vertical divergence;photonic bandgap122|304|3更新时间：2020-08-12
- 摘要：Based on the 10 nm scale image processing technology and the surface plasmon resonance properties of metal nanostructures, the colorful SEM microimages can be printed by changing the size and the morphology of the metal nanostructures. As the results, the graphics pixel can be controlled in 60 nm scale (about 1 million dpi). Furthermore, using the image processing technology, the objective image can be generated faster than before and this will benefit the industrial production because of the artificial intelligent. While using the electron-beam lithography (EBL) and the deposition technology, the different structures of the Au/Ag nanoparticles can be accurately generated. And according to this paper, the results show that different structures of the Au/Ag nanoparticles can carry different surface plasmon resonance properties so that the luminescent properties of these nanoparticles can cover the visible wavelengths. In this paper, using four same size nanoparticles to represent one color can enhance the consistency between pixels. The luminescent properties of these nanoparticles will be shown by changing the size of the Au/Ag nanoparticles. And the colorful SEM microimages will also be generated while using the image processing algorithms for the permutation and combination of the different size of the Au/Ag nanoparticles.关键词：plasmon resonance;nanofabrication;metal nanostructures;image processing113|163|0更新时间：2020-08-12
- 摘要：Two-dimensional numerical simulation was performed by FLUENT for the HVPE reactor with different segmented annular inlets, considering the transport model and transport-growth model, with the flow rates of GaCl, NH3 and N2 kept constant. When only considering the gas transport, the results show that the flow uniformity is improved by increasing the number of annular inlets and the 8 annular inlets reactor can give the most uniform temperature distribution on the substrate. The GaCl concentration on the substrate of 4 annular inlets is high, but the uniformity is poor, and the Ⅴ/Ⅲ ratio is also low. The 8 and 12 annular inlets can give uniform GaCl concentration distribution on the substrate, and high Ⅴ/Ⅲ ratio. When the GaN growth rate is also considered, the results show that the growth rate for 8 inlets is higher than that of the 12 inlets because of the thinner boundary layer of the GaCl concentration, although the GaCl concentration for 8 annular inlets is lower than that of the 12 annular inlets on the substrate. Thus, the 8 annular inlets is more advantageous to the GaN HVPE growth.关键词：HVPE;GaN;annular inlet;reactor design;simulation112|106|0更新时间：2020-08-12
- 摘要：We theoretically and numerically demonstrate one-way action of terahertz surface plasmon polaritons in an axially uniform waveguide system that comprises of εhigh-dielectric layer of thickness d inset between a εlow-dielectric layer and magneto-optical semiconductor. The calculation shows that the system exist one-way action under an external magnetic field. The propagation of surface plasmon polaritons in a three ports system can be controlled by the coupling of micron size metal particles and the external magnetic fields.关键词：one-way action;surface plasmon polaritons;terahertz85|76|0更新时间：2020-08-12
- 摘要：Soil spectral analysis technology has features of fast analysis speed, low cost, no risk, no damage, and it can inverse a variety of ingredients at the same time. Based on hyper-spectral imaging technology, we can quickly obtain soil properties and its spatial distribution characteristics. In this paper, we design a UAV hyper-spectral imager based on the demand of farmland soil monitoring. The Offner convex grating spectral imaging system was selected to achieve non-spectral line bending and colorless distortion design results. The diffraction efficiency is 15%~30% in the range of 400~1 000 nm wavelength. The ground imaging results are clear, it can obtain hyper-spectral images of ground target of covering a width of 0.6 km and ground resolution of 0.6 m at 3 km altitude. It provides 120 spectral bands of hyper-spectral images at the wavelength range of 0.4~1.0 μm. The spectral data are accurate and stable. The results show that this hyper-spectral imager meets the design requirements and can quickly obtain the high-precision imaging spectra of the agricultural soils, thus achieving the monitoring of farmland soil.关键词：hyperspectral imager;farmland soil;monitor104|116|0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