最新刊期
卷 33 ， 期 3 ， 2012
- 摘要：Enhanced performance and stability of polymer solar cells based on regioregular poly(3-hexylthiophene) (P3HT) and methanofullerene [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) blend were obtained by using cesium carbonate (Cs2CO3), lithium benzoate (C6H5COOLi), poly(ethylene-oxide) (PEO) as cathode buffer layer. The improved performance may attribute to the cathode buffer layer which reduces the interface resistance between the active layer and the cathode and enhances the interior electric field that may result in efficient charge transportation. In addition, the cathode buffer layer may serve as an effective oxygen and moisture diffusion barrier for the organic solar cells. The organic cathode buffer layer is superior to the inorganic materials. Solution processed conjugated polymer bearing strong polar groups in the side chains is a promising candidate as an interlayer to improve the efficiency of electron collection and to reduce the ambience influence on the stability of polymer solar cells.关键词：polymer photovoltaic cells;buffer layer;power conversion efficiency;stability142|198|3更新时间：2020-08-12
- 摘要：Na2CaSiO4∶RE3+(RE=Ce3+,Tb3+,Eu3+) (NCS) samples were synthesized by high temperature solid-state reaction and their luminescence characteristics were investigated. The photoluminescence (PL) spectra of Ce3+,Tb3+ and Eu3+ doped NSC samples show characteristic intra-configurational 4f-5d transitions of Ce3+,4f-4f transitions of Tb3+ and 4f-4f transitions of Eu3+ under ultraviolet excitation. The emission intensity increases with the concentration of RE3+, and then decreases when doping concentration over a certain value. The concentration quenching value of Ce3+, Tb3+ and Eu3+ are 0.13, 0.13 and 0.12, respectively. The Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of Ce3+,Tb3+ and Eu3+ doped NSC samples are (0.17,0.17), (0.34,0.58) and (0.66,0.34), respectively.关键词：Na2CaSiO4;phosphor;rare earth doped141|38|4更新时间：2020-08-12
- 摘要：A novel aromatic polyether with a 1,8-naphthalimide unit main chain (PENI) was synthesised by nucleophilic substitution reaction. The molecular weight of the polymer is 4 300. The structure of monomer and polymer were characterized by FT-IR and NMR, and photoluminescence and cyclic voltammetry of the PENI were also investigated. Along with the increasing of molecular weight, the emission of the PENI film red-shifted about 14 nm. The HOMO-LUMO and energy gap (Eg) of PENI was about -5.64/-2.93, 2.71 eV, respectively.关键词：1;8-naphthalimide;photoelectric functional polymer;nucleophilic substitution reaction93|116|0更新时间：2020-08-12
- 摘要：A series of (Y1-x-y,Gdy)2O3∶xEu3+(x=0.06~0.10,y=0,0.20~0.25) red phosphors have been synthesized by co-precipitation synthesis. The crystal structure, surface morphology and spectral characteristics of the samples were investigated by X-ray diffraction (XRD), SEM and fluorescence spectrophotometer. The effects of doping density of Eu3+and Gd3+, the calcining temperature and the addition of surfactant on the characteristics of luminescence have also been investigated. It is found that the synthesized crystalline powders are cubic system. The introduction of Gd3+ would make the crystal structure distorted and aggrandize the cell parameters, which may improve samples' color purity and luminous efficiency. The completely crystallized phosphors were obtained at 900 ℃, which is nearly 500 ℃ lower than the temperature of solid-state method. The particle size of the samples is loose, and their sizes are ranging from 300 to 400 nm. The optimum emission intensity of 613 nm is obtained when the x=0.08, y=0.23. Therefore, it suggests that the sample phosphors have a good spectral characteristics and can be used as PDP red phosphors.关键词：(Y1-x-y;Gdy)2O3∶xEu3+;3D-PDP;co-precipitation synthesis;red phosphors152|266|2更新时间：2020-08-12
- 摘要：Branched polyethylenimine (B-PEI) coated NaYF4∶Yb3+, Er3+ nanoparticles with size about 45 nm were successfully prepared via a solvothermal method in water and diethylene glycol using B-PEI as surfactant. The strong upconversion luminescence from the sample can be observed under excitation of 980 nm diode laser at room temperature. The amino groups of B-PEI existing on the nanoparticles can be used for attachment of biomolecules. The cell viability experiments show that the samples have lower cell toxicity. The results presented in this study provide a new insight for the upconversion luminescence nanoparticles in the biomedical applications.关键词：upconversion luminescence;nanoparticles;water soluble;cell viability115|103|1更新时间：2020-08-12
- 摘要：Trivalent dysprosium ions co-doped NaYF4 up-conversion luminescence nanoparticles were synthesized. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), infrared spectrometer (FT-IR) and fluorescence (FL) spectrum. The effect of annealing temperature and the concentration of Dy3+ co-doping on the crystal structure, morphology and luminescence properties were investigated. The absorption spectra shows that the absorption peak band centered at 776 nm corresponds to 6H15/2→6F5/2 transition of Dy3+ ion. Under 776 nm excitation, the NaYF4∶Dy3+can emit strong green and blue emission. The blue emitting light results from the transition of 4F9/2→6H15/2 of Dy3+, green emitting light is from the transition of 4F9/2→ 6H13/2 of Dy3+. XRD analyses show that the UCNPs are pure cubic phase NaYF4 nanocrystals.关键词：upconversion luminescence;NaYF4∶Dy3+;anneal130|108|1更新时间：2020-08-12
- 摘要：Flower-like hierarchical Bi2WO6 and Bi2WO6∶Er3+ microspheres were synthesized by a hydrothermal method. Bi2WO6∶Er3+ microspheres exhibited pure green upconversion lumminescence (2H11/2/4S3/2→4I15/2) under 980 nm excitation. The annealing temperature as well as Er3+-doped content had not evident influence on the spectrum shape of Er3+. Bi2WO6∶Er3+, in addition to the aforementioned luminescence properties, also showed high photocatalytic activity for the degradation of RhB under visible light irradiation. The photodegradation efficiency of RhB reached 68.9% and 95.3% for Bi2WO6 and Bi2WO6∶Er3+, respectively. The enhancement of photocatalytic activity would be related to the both the larger RhB adsorbance and the visible-to-ultraviolet upconversion of Er3+ ions.关键词：Er3+;luminescence;photocatalytic activity127|232|0更新时间：2020-08-12
- 摘要：Highly-ordered Y-branched TiO2 nanotube arrays were fabricated on the Ti foils in ethylene glycol containing 0.5% NH4F(mass fraction)and 5% H2O(volume fraction) by a three-step electrochemical anodic oxidation via increasing the electrolyte temperature. The effect of pretreatment process on surface morphology and the growth mechanism of Y-branched TiO2 nanotubes were discussed. Four samples were fabricated by anodic oxidation at different temperature ranges of 20~60 ℃. The results show that phenomena such as annular nanowires, nanotube breach or length reduction etc. will appear in the surface morphology of Y-branched TiO2 nanotubes when electrolyte temperature is set at 40 ℃ or more in the third step of anodic oxidation, which is not conducive to ensuring the overall quality of Y-branched TiO2 nanotube arrays. However, the ideal temperature range is 30~40 ℃ in the third step during the anodizing process.关键词：anodic oxidation;Y-branched TiO2 nanotube;electrolyte temperature108|94|1更新时间：2020-08-12
- 摘要：The Er3+/Yb3+ co-doped oxyfluoride silicate glass ceramics were prepared. The fluorescence spectrum and absorption spectrum were characterized. The up conversion spectrum showed that there were four luminescence centres at red(645 nm),green(545,522 nm) and blue(480 nm), corresponding to the 4F9/2→4I15/2,4S3/2→4I15/2,2H11/2→4I15/2,4F7/2→4I15/2 transitions of Er3+. The slope of fitted lines was 1.81,2.39,1.95,2.15, respectively, which indicated a two-photon absorption process. The results showed that the samples lowered phonon energy and greatly improved the up-conversion efficiency by heat treatment. Judd-Ofelt theory was employed and the intensity parameters were obtained.关键词：glass ceramics;fluorescence spectroscopy;Absorption spectroscopy;upconversion97|79|1更新时间：2020-08-12
- 摘要：ZnO/CuO one-dimensional core/shell nanowires have been synthesized by sequential growth of core and shell, respectively. Phase and structural analyses reveal that the ZnO core has single crystalline phase whereas the CuO shell has polycrystalline phase covering on the surface of the core. The photoluminescence (PL) properties of ZnO nanowires change with the CuO shell thickness. The photoluminescence intensity increases when the shell is very thin, which is attributed to the surface modification by CuO shell. When the shell gets thicker, the intensity of the photoluminescence does not change any more because a type-I band alignment is formed between the core and shell. The experimental result is discussed.关键词：ZnO/CuO;core/shell nanowires;photoluminescence properties;type-I band alignment95|255|1更新时间：2020-08-12
- 摘要：The effects of active layer thickness, capping layer thickness and transport layer thickness on the optical absorption of active layer have been investigated by employing MATLAB and an optical model based on the transfer matrix method. The results reveal that the absorption of active layer is mainly attributed to its thickness which could be optimized by the microcavity effect. Furthermore, it demonstrates that active layer optical absorption can be effectively improved by adjusting the thickness of capping layer and transport layer. At last, the results show that the solar cells with 10 nm thick transport layer have superior optical and electrical performance than those without transport layer; the optimized thickness of ZnS layer and the thickness of Alq3 layer are 30 nm and 60 nm, respectively. The research of optical properties of organic solar cell on Si substrate provides a theoretical basis to its future structural design and application.关键词：organic solar cell;optical absorption;transfer matrix method;optical electric field distribution95|349|1更新时间：2020-08-12
- 摘要：Catalyst-free InP/InGaAs core-shell nanowires were grown on Si(100) substrates by metal-organic chemical vapor deposition. These nanowires have quite different properties to Au-catalyst core-shell nanowires. By using scanning electron microscope, we found that the catalyst at the top of the InP nanowires had been transformed into crystal after the InGaAs core grown on them. Meanwhile, the diameter of the nanowires has greatly increased with their length changed quite little. The X-ray diffraction patterns indicate that the transformation of the catalyst is attributed to the temperature rise under PH3 protection before InGaAs core growth. By transmission electron microscope and energy dispersive X-ray spectroscopy, it is proved that the transformation of catalyst is prior to the InGaAs core growth and is cover by InGaAs which is same to the nanowires sidewall.关键词：catalyst-free;MOCVD;nanowires;InP/InGaAs core-shell117|164|1更新时间：2020-08-12
- 摘要：High efficiency white organic light-emitting diodes (WOLEDs) with high color rendering index (CRI) was fabricated. The white light was composed by the blue emission of 9,10-di(2-naphthyl) anthracene and the enhanced green and red emissions of tris-(8-hydroxyquinolinato) aluminum and 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran, respectively. The WOLED shows the Commission Internationale de l'Eclairage-1931 coordinates vary from (0.343 2, 0.339 7) to (0.324 3, 0.321 8), the correlated color temperature varies from 5 035 K to 5 915 K and all the CRIs exceed 90 when the driving voltage changes from 8 V to 12 V. A maximum brightness of 27 853 cd/m2 at 14 V and a peak current efficiency of 9.58 cd/A at 7.5 V are attained, respectively. The electroluminescent (EL) spectrum is tuned by changing the thickness of the green and red emission layers. The efficiency enhancement is realised by sensitising the green and red light emissions. The maximum efficiency is increased by 73.6% compared to the control device.关键词：co-host;WOLED;CRI91|76|0更新时间：2020-08-12
- 摘要：The characteristics of photonic band gap (PBG) of a one-dimensional (1-D) photonic crystal (PC) with dual-periodical heterostructures were studied by transfer matrix method. The results show that a PBG range from 512 nm to 960 nm appeared in the PC and five very narrow transmittance peaks exhibited in this gap. The authors put emphasis on the case of the PC with complex refractive index layers, as well as the meso-piezooptic effect of the strained PC. We found that the transmittance peaks gain when the imaginary part is negative. And with the increase of the absolute of the imaginary part, the transmittance peaks increase firstly then decrease even occur attenuation lastly. However, the transmittance peaks change into absorption if the imaginary part is positive. On the case of the strained PC, the variation of transmittance peaks presents a shape of L as the stain increases.关键词：dual-periodical photonic crystal heterostructure;an imaginary part of refractive index;mesoscopic piezophotonic effect;transfer-matrix;filter109|164|2更新时间：2020-08-12
- 摘要：The reflectivity spectra of 808 nm/980 nm double band mirror (DBM) are characterized in the paper. According to the structure of the DBM, the thermal model of Optically Pumped Vertical-External-Cavity Surface Emitting Semiconductor Lasers (OPS-VECSELs) with DBM is constructed and the distribution of thermal load in the VECSEL wafer is presented. The thermal characterization of OPS-VECSELs with DBM is analyzed in detail by finite element method. The results indicate that VECSEL wafer with DBM has better thermal properties and poorer thermal performance than with DBM when they have the same reflectivity (R=99.96%). So VECSEL wafer with DBM is more suitable for making high power semiconductor laser than with DBM. The theoretical analysis results will be provided as theory reference for VECSEL wafer structure optimization and experimental.关键词：optically pumped semiconductor laser;finite element method;double band mirror (DBM);thermal effect97|144|1更新时间：2020-08-12
- 摘要：The fluorescence emission of Rhodamine 6G dye molecules located near the physically polished nanostructure silver substrate (PPNSS) with and without PATP monolayer was investigated. The quenching effect is observed when the dye molecule is directly adsorbed onto PPNSS without the formation of PATP monolayer. However, the fluorescence is enhanced when the PATP layer is formed. This phenomenon is discussed by taking into account the formation of PATP monolayer, the nonradiative energy transfer process and the local surface plasmon resonance at rough silver surface. A theoretical model is proposed for analyzing the role of the PATP layer formed on the metal substrate. It indicates that isolated spacer formed on metal nanostructure substrate can enhance fluorescence.关键词：surface enhanced fluorescence;physically polished silver surface;surface plasmon resonance;PATP spacer88|83|1更新时间：2020-08-12
- 摘要：Gadoped ZnO (GZO) thin films were grown on single crystal silicon (111) and quartz glass substrates by pulsed laser deposition (PLD) method at different substrate temperatures from room temperature to 750 ℃. The change of substrate temperature leads to different diffusion and desorption rates for adsorption atoms resting on substrate surface, and results in different crystalline quality for GZO thin films. The GZO thin film grown at 450 ℃ has the best crystalline quality. The carrier concentration monotonically decreases with the increase of substrate temperature, which is related to the intrinsic defects in films. The Hall mobility first increases and then decreases with the substrate temperature increasing, it results from the variation of grain boundary scattering. And the lowest resistivity ~0.02 Ω·cm is obtained in the film prepared at 450 ℃. With the increase of substrate temperature, the optical band gap becomes narrow due to the monotonic increase of carrier concentration. The average transmittance in visible region is above 85% for all the GZO samples. Our results exhibit that the optical and electrical properties of GZO thin films prepared by PLD method can be adjusted by the change of substrate temperature.关键词：Ga doppend ZnO;pulsed laser deposition;substrate temperature96|142|0更新时间：2020-08-12
- 摘要：Organic bulk-heterojunction solar cells were prepared using two conjugated polymers(P3HT,MDMO-PPV) as electron donor, respectively, and a conjugated polymer (TQ1)as electron acceptor. The best performance was achieved with the mass stoichiometry of 1∶1. It is found that thermal annealing has a pronounced effect on device performance. Annealing can alter the morphology of active layer, which results in the increase of distance for exciton diffusion and the decrease of interface area for exciton separation, leading to the decrease device performance. It is observed that solvent has little effect on device performance, which is different from fullerene-based polymer solar cells. Moreover, it demonstrated that crystallinity of donor polymer also has a significant effect on device performance, despite of similar LUMO and HOMO energy bands.关键词：acceptor polymer;organic solar cells;thermal annealing;crystallinity;film morphology102|201|1更新时间：2020-08-12
- 摘要：High quality ZnO piezoelectric thin films have been grown by RF-MBE on sapphire (0001) substrate with MgO and ZnO double buffer layers. Only ZnO (0002) diffraction peak was observed in the XRD patterns, with a narrow FWHM of 0.10°. A sharp absorption peak and a steep absorption edge were observed in absorption spectra, only one PL peak from free exciton emission, with a narrow FWHM of 12.7 nm, was obtained in PL spectra. The electrical resistivity of the ZnO thin films is up to 4×107 Ω·cm. These results indicate that ZnO thin films have good c-axis orientation with wurtzite structure, low defect densities and low background carrier concentration. This is mainly due to that the MgO and ZnO double buffer layers accommodated the mismatch between the ZnO thin films and the sapphire substrate. The SAW devices based on the high quality ZnO thin films were fabricated. The center frequency of the surface acoustic wave (SAW) filter is 835 MHz, and the SAW propagation speed is up to 5 010 m/s, indicating that the MgO and ZnO double buffer layers not only improved the quality of the ZnO films, but also improved the piezoelectric properties of the films.关键词：ZnO;MgO buffer layer;SAW128|113|1更新时间：2020-08-12
- 摘要：Perylene-3,4,9,10-tetracarboxylic acid dianhydride (PTCDA) thin films were vacuum evaporated on Au, Al and ITO substrates, their structure and morphology were analysed by X-ray spectroscopy (XRD) and atomic force microscope (AFM). The results show that most of PTCDA molecules don't lie parallel to the substrate, which indicates that electron transport dominates the current conduction in the direction perpendicular to the film plane. PTCDA films grown on ITO and Au arrange regularly. It shows good electronic transport properties perpendicular to the film plane. But the grains of PTCDA film grown on Al arrange disorderly resulting in poor performance of electronic conduction. By the thermionic emission theory at metal-organic interface and space charge limited current conduction theory in the organic bulk and considering the electric field effect on mobility, current density-voltage curves of ITO/PTCDA/Al devices were fitted in different PTCDA film's thickness. The numerical value of electron mobility dependent on electric field was determined for the specific PTCDA film thickness.关键词：PTCDA;organic semiconductor;carrier mobility;charge transport104|186|1更新时间：2020-08-12
- 摘要：Based on combination of binary convex function discriminant theorem with clustering analysis, a new method of characteristic region selection for three-dimensional fluorescence spectrometry is proposed. By this method, the convex regions with valid spectral data are obtained.Experiment for detecting total organic carbon (TOC) in water and AFB1 in liquor are carried out. The experimental results show that the proposed method improves the accuracy of the regress model with increase of 6.17% and 4.97% respectively.关键词：three-dimensional fluorescence spectrometry;characteristic regions selection;binary convex function;cluster analysis118|642|3更新时间：2020-08-12
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