Jorunal of Functional Materials

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Controllable preparation of silicon nanowires in Metal-assisted chemical etching

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. 2014, 45(12-光电): 1-0.

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Silicon nanowire is regarded as one of the most promising optoelectronic materials because of its unique optoelectronic characteristics. This article focuses on the influence of various controllable parameters in the preparation of silicon nanowires using metal-assisted chemical etching and we have prepared the silicon nanowires successfully. According to the study, high concentration of plating solution and long plating time will form silicon nanowires in low density; the etching rate and morphosis of silicon nanowires are controlled by the concentration of etching solution. The etching time have an influence not only on the length of silicon nanowires, but also on the density, while drying with nitrogen can optimize the aggregation of silicon nanowires.

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Preparation and Photocatalytic Property of Graphitic Carbon Nitride (g-C3N4) Hybridized TiO2 Nanometer Materials

. 2014, 45(12-光电): 2-0.

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Graphitic carbon nitride (g-C3N4) hybridized TiO2 nanometer materials was prepared by annealing metatitanic acid and melamine. The prepared composites were characterized by X-ray diffraction (XRD), X-Ray photoelectron spectroscopy(XPS), Fouriertransform infrared spectroscopy (FT-IR) and Thermogravimetric-differential scanning calorimetry analysis(TG-DSC), Transmission electron microscopy(TEM), Ultraviolet–visible diffuse reflection spectroscopy (UV–vis), Three- dimensional fluorescence spectroscopy (FS), and the N2 gas adsorption Brunauer-Emmett-Teller method (N2-BET). The catalysis experiment show that the g-C3N4 hybridized TiO2 composites, which the proportion of melamine and metatitanic acid is 1 and calcined at 500°C, exhibited higher activity under visible light irradiation, while the photodegradation rate of 10mg/L methylene blue reached to 83%.

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Preparation and application of ATO conductive films in organic photoconductor of laser printer

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. 2014, 45(12-光电): 3-0.

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ATO nanopowders were prepared with SnCl4.5H2O and SbCl3. Then nanopowders were dispersed into the insulating thermosetting resins to produce conductive slurry. Conductive coating with certain resistivity was finally obtained by painting the slurry on an aluminum surface. An organic photoconductor (OPC) apparatus was constituted by painting a pre-coating layer, a charge generating layer and a transporting layer successively above the conductive layer. The OPC apparatus showed excellent characteristics such as high charging capacity, small dark decay rate, low residual potential and superior photosensitivity. Effects of ATO content on the film resistance, the film surface chargeability and performance of OPC apparatus were studied. It is concluded that the film with solid content of 60-70% and film thickness of 12-14μm showed excellent mechanical properties and capacity preventing environmental influence. The volume resistivity of the appropriate film is 107-109Ω.cm. Performance parameters of the optimal OPC apparatus are V0=795.95V, Vr=37.01V, DDR=26.27V/s, E1/2=0.13μJ/cm2.

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The fabrication of ultralong titanyl phthalocyanine micron wires by using solution method

. 2014, 45(12-光电): 4-0.

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One-dimensional ultralong titanyl phthalocyanine sub-micron wires have been synthesized by solution method. The optical micrographs of TiOPc sub-micron wires prepared by different solvents indicating that alcoholic solvents are in favour of getting long TiOPc wires. Meanwhile, we find that change of mass concentration has a great influence on the length of nanowire in the solution. The TiOPc sub-micron wires were determined by atomic force microscope and scanning electron microscope. The results show that aspect ratio of the wires can reach 100. Organic transistors based on these wires were fabricated and showed typical p-channel characteristics.

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Synthesis and Growth Mechanism of ZnSe Submicro-tubes

. 2014, 45(12-光电): 5-0.

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Polycrystalline ZnSe submicro-tubes on the zinc substrate were fabricated via the sacrificial zinc oxide temple route in HSe– ion solution of TEA at 150 ℃ for 8 hours. The structures and morphologies of as-synthesized samples were characterized by FE-SEM, EDS, XRD, TEM and SAED. The average diameter of ZnSe tubes was 100-150nm with the closed ends, the regular open ends, irregular open ends, and even the semi-tube ends. The wall of submicro-tubes consists of the particles with the diameter of 30-40 nm. According to the growth unit model of anion coordination polyhedron, the formation mechanism of ZnSe submicro-tubes is suggested.

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Growth and physicochemical and optical characterization of a novel organometallic nonlinear optical crystal: CdHg(SCN)4(C2H5NO)2

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. 2014, 45(12-光电): 6-0.

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A novel potentially useful second harmonic generation (SHG) organometallic nonlinear optical crystal: cadmium mercury thiocyanate bis(N-methylformamide), CdHg(SCN)4(C2H5NO)2 (CMTN) has been prepared, and large highly-optical quality single crystals with dimensions up to 30?27?9 mm3 have been grown by the temperature-lowering method. The structural, physicochemical, thermal decomposition and optical properties are characterized by elemental analyses, X-ray powder diffraction, Fourier transform infrared and Raman spectroscopy, thermal analysis and UV/Vis/NIR transmission. CMTN possesses good physicochemical stabilities up to 128.5?C, and the UV transparency cutoff is 358 nm.

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Nonlinear Ge-As-Se chalcogenide fibers

;;;; ;;Zhi-yong YANG;;

. 2014, 45(12-光电): 7-0.

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Ge-As-Se chalcogenide glasses with MCN of 2.45-2.5 are promising nonlinear optical materials in infrared regions since they exhibit excellent infrared transparency, high third-order nonlinearity, and ultra-low photo-induced refractive index change. We therefore fabricated high purity Ge-As-Se glasses using a dynamic distillation technique, and drew core/cladding fibers through the rod-in-tube approach. The fibers show good transmittance in the 2-8μm spectral region. The background loss is around 1dB/m, and the impurity related peak loss is about 6dB/m.

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Study on preparatikn and properties Of Y-TiO2 photocatalyst

. 2014, 45(12-光电): 8-0.

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Yttrium doped TiO2 photocatalysts were synthesized by sol-gel process using Yttrium nitrate and tetrabutyl titanate as precursors and characterized by XRD，DSC-TGA，FT-Raman，UV-Vis and PL methods. The influences of different preparation condition on properties were studied. The photocatalytic activity of Y-TiO2 was investigated by measuring the degradation rate of methylene-blue (MB) under the irradiation of fluorescent lamp. The results show that yttrium doping can not only inhibit the phase transition of anatase to rutile but also broaden the absorption region to visible light and inhibit the recombination of the photo-generated electrons and holes. The photocatalytic activity of the sample with molar ratio of Y:TiO2 =0.6% and sintered at 500℃ for 4 hours is the best under the irradiation of fluorescent light，it is 97.32% within 3 hours and significantly higher than that of Degussa P25(58.62%) under the same experimental conditions.

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Hydrothermal synthesis and photocatalytic properties of Ag ions modified Bi2WO6

Wen ZHAO ;;;;

. 2014, 45(12-光电): 9-0.

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A series of Ag ions modified Bi2WO6 photocatalyst were synthesized successfully by hydrothermal method with solid silver nitrate and characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), X-ray Photoelectron Spectrometer (XPS), Energy dispersive X-ray detector (EDS) and UV-Vis diffusion reflectance spectra techniques (DRS). Our result indicates that Ag ions may replace Bi3+ ions of bismuth tungstate into the crystal lattice, which regulates the forbidden band width. On the other hand, Pure Bi2WO6 and Ag ions modified Bi2WO6 are both ball-like samples self-assembled with nanoplates. Compared with pure Bi2WO6, Ag ions modified Bi2WO6 samples have higher crystallinity and relatively closer arrangement in nanoplates, also more prominent photocatalytic activity. The optimization of morphology and energy gap is the main reason to enhance the photocatalytic performance in this experiment. And the degradation rate of RhB is increased by almost 42% while the quantity of AgNO3 adding content is 10 mol%.

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Photochemical and electrochemical properties of tungsten trioxides and tungsten trioxide hydrates

Ai-ling YE

. 2014, 45(12-光电): 10-0.

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Abstract: Tungsten trioxides and tungsten trioxide hydrates were synthesized via mixing tungsten with H2O2 in a water bath. Samples were characterized by X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), cyclic voltammetry (CV). The UV-visible photo activity was evaluated through the photo degradation of methyl orange in aqueous solution. The effects of photoreaction conditions on the photoactivity of the obtained samples were investigated in detail. Cyclic voltammetry measurements showed that WO3?0.33H2O, WO3?0.33H2O and WO3 have different oxidation-reduction potentia，that lead to a higher conductive band of WO3?0.33H2O than H+/H2. The experimental results indicated that photoactivity of WO3?0.33H2O was deeply related with the crystal structure and energy band structure.

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Study on Properties of TiO2 Photocatalysts Doped with Co

. 2014, 45(12-光电): 11-0.

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Co doped TiO2 powder (Co-TiO2) were synthesized by sol–gel method. The obtained samples were characterized by XRD、FT-Raman、UV-Vis、PL, respectively. The results show that Co-doping can decrease the phase transition temperature, broaden the absorption spectrum to the visible light region, and inhibit the recombination of photoelectron-hole pairs. The experiments of photocatalytic degradation of methylene blue (MB) indicate that the photocatalytic activity of the Co-TiO2 powder prepared at Co:Ti=0.002(molar ratio) and the calcinated temperature of 400℃ is the best. Under the fluorescent light irradiation, the degradation rate of the Co-TiO2 sample to methyl blue reaches 90.56%, which is obviously higher than 44.95% of P25 TiO2 photocatalyst which made in Degussa, German.

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Study of Ionic Liquids Applications in Soft Optical Functional Materials

;mingxin GU

. 2014, 45(12-光电): 12-0.

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Due to ionic liquids special features, zero steam pressure, low melting point, thermal stability, and many others, it can, as a potential efficiency, green optical materials or medium, draw more and more attention of the countries' scientists. In this paper, it introduces the ionic liquid, as in recent years show materials, optical transmission optical materials, optical energy storage material, photoelectric material, solar battery materials, and other aspects of the research progress in a relatively comprehensive paper, analyzes and discusses the application of ionic liquid, as optical materials of the problems existing in the field, puts forward the ionic liquids in optical of research in the field of thinking and predicts their future prospect.

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Research progress in the band engineering and applications of graphene

. 2014, 45(12-光电): 13-0.

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During the last decade, graphene has been extensively paid attentions, due to its extraordinary physical properties, chemical tunability, and potential for various applications. However, graphene is an intrinsic semimetal with a zero bandgap, which considerably hampers its applications in many areas. Therefore, it is significantly important to study the band engineering of graphene, and transform graphene from metal into semiconductor with a sizable bandgap. In this paper, we present an overview of the research progress on graphene electronic structures and its bandgaps in recent years, and also explore the potential application areas of the semiconducting graphene. It is expect to provide fundamental references for the future applications and industrializations of graphene.

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Preparation and Optical Properties of Bialayer Silver Dendritic Nanostructure at Visible Optical Frequencies

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. 2014, 45(12-光电): 14-0.

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In this paper, an Ag/TiO2/Ag composite configuration, of which the Ag has dendrite-like morphology, was successfully prepared on a transparent ITO glass substrate via the bottom-up electrochemical deposition method. By adjusting the process conditions, the transmission of sample can be altered from multiple frequencies to single frequency. And the operating frequency of sample can be flexibly tuned via changing deposition process. Three kinds of samples that respectively operate in the region of green, yellow, and red wavelengths were fabricated. In addition, we measured the flat-focusing property of the sample working at green wavelengths. It is found that the unique properties of transmission and flat-focusing phenomenon can be attributed to the electromagnetic resonance induced by the interaction between optical waves and the composite configuration.

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Organic additives assisted hydrothermal synthesis of micro-nano fluorescent materials

Yu-Long Yu BAI;;

. 2014, 45(12-光电): 15-0.

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Generally, the physical and chemical properties of inorganic materials are strongly related to their chemical composition and microstructure, as well as particle size and morphologies. Among all synthetic methods, the hydrothermal method has attracted more and more attention because of its outstanding advantages on controlling the size and morphology: precise controlling over the hydrothermal synthesis conditions leads to the success of the preparation of uniform and well-dispersed materials, with low pollution and low energy consumption. The dispersion and homogeneity are very important for the fluorescent materials, and the organic additive-assisted hydrothermal synthetic strategies may realize further control of the morphology, uniformity and diversity of morphologies of the fluorescent material via the introduction of various organic additives. In this paper, hydrothermal synthesis of micro-nano fluorescent material assisted by surfactants, biological macromolecules, organic acids, organic solvent and other organic additives were reviewed and were briefly discussed. Finally, we conclude the problems existing in the hydrothermal synthesis and present the future prospects of this research area.

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Preparation and photocatalytic performance of N-doped ZnIn2S4 photocatalysts under visible light illumination

wenhui yuan ;

. 2014, 45(12-光电): 16-0.

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A series of ZnIn2S4 photocatalysts doped with different amounts of nitrogen (N-ZnIn2S4) were prepared by using ZnIn2S4 and urea, where ZnIn2S4 was obtained via hydrothermal route as precursor and urea was employed as nitrogen source. These as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Visible absorption spectra (UV-Vis) and X-ray photoelectron spectroscopy (XPS). The effect of N dopant amount in the N-ZnIn2S4 on crystalline structure and photocatalytic performance of methylene blue (MB) degradation under visible light illumination was investigated. The results indicate that N doping can influence the crystalline structure and morphology of ZnIn2S4 and enhance visible light absorption of photocatalysts. The performance of MB degradation was remarkably improved by using N-ZnIn2S4 compared with pure ZnIn2S4, and N-ZnIn2S4 exhibits quite good catalytic stability. Meanwhile, the mechanism for enhanced photodegradation activity was also analyzed.

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Fabrication of Al2O3 photosensitive films and micro- patterning microstructures

zhezhe wangZHAO Gao-Yang;;;

. 2014, 45(12-光电): 17-0.

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In this paper, an novel approach for fabricating Al2O3 microstructure based on photosensitive sol-gel and UV laser lithography was introduced. Stabilized and UV photosensitive Al-contained metal chelate and thin films were prepared with Al(O-Sec-Bu)3 and H（C10H12O2）as the precursor and chemical modifier, respectively. The characteristics of UV and IR spectra of the films and their variations in the process of UV irradiation were investigated. The results showed that the gel films had absorption peaks at about 251, 321 and 368 nm due to the formation of chelate complex. These peaks gradually decreased with irradiation in time, which indicated the photosensitive properties of the Al2O3/H gel films. several size and profile Al2O3 micro-patterning were fabricated by using UV lithography and the minimum line-size obtained in this paper was about 437nm.

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Study on visible and infrared luminescence properties of Y2O2S:Ho3+,Yb3+ nanocrystals under 980 nm excitation

;Yao FuXi-xian Luo

. 2014, 45(12-光电): 18-0.

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Near-spherical Y2O2S:Ho3+,Yb3+ nanocrystals (NCs) were prepared by coprecipitation method followed by a solid-gas sulfuration technic. The nanocrystals are in hexagonal structure, and the particle size is 40 nm on average. Under the excitation of 980 nm laser diode (LD), more systematic researches on luminescence properties of Y2O2S:Ho3+,Yb3+ NCs in a broad range from 450 nm to 1500 nm have been performed. According to the luminescence measurement results, three different emissions located at 545nm, 655nm, 1180nm can be observed, which are derived from 5F4/5S2→5I8, 5F5→5I8, 5I6→5I8 transitions, respectively. The upconversion luminescence (UCL) efficiency of Ho3+ in the nanocrystals can be improved obviously by co-doping Yb3+. However, because of the high-energy vibration quantum produced by surface adsorption, the 5F4/5S2→5F5 and 5I6→5I7 multi-phonon relaxations of Ho3+ are very efficient, and the red emission could be held up hardly. In addition, the increasing content of Yb3+ (no more than 6 mol%) can not only improve the population of 5F4/5S2 and 5I6 energy levels, but also restrain the 5I6→5I7 multi-phonon relaxation in a certain degree, which results in an enhancement on green and infrared (IR) emissions, but a decrease on red emission. Nevertheless, the intensity ratio of green to red emission (IG/IR) obtained in Y2O2S:Ho3+,Yb3+ NCs is only 3.75, which is much smaller than that of micron Y2O2S (46.6). This is because of another possible populating process (5F4/5S2→5F5) of 5F5 energy level. When Yb3+ content is higher than 6 mol%, (5F4/ 5S2,2F7/2)→(5I6,2F5/2) inverse energy transmission make the green and red emission intensities decrease sharply, but this process is beneficial to the population of 5I6 energy level and leads to an enhancement on IR emission intensity. These changes weakens the IG/IR ratio, and give rise to a remarkablely increase on IIR/IR.

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Synthsis and photoluminescence properties of a wide band-gap pyridone derivatives

Yun GUO

. 2014, 45(12-光电): 19-0.

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The paper designed and synthesized a wide band-gap pyridone derivatives 3,5- dimenthyl-6-nitrile-pyridone(DNPE).The chemical structure of the complex was confirmed by FT-IR spectra, 1H NMR and elemental analysis techniques, and its crystal structures were also determined. DNPE is triclinic crystal system, P-1 space group, a = 3.9049?, b = 7.3288?, c=12.694?; α = 77.09°, β = 89.16°, γ = 89.40°. Optical band gap and photoluminescence were investigated by UV-vis absorption spectra, cyclic voltammetry experiments and fluorescence emission spectrum. The results show that its UV-vis absorption peak in alcohol solution were at about 215 nm, 237 nm, 330 nm, maximum emission peak was at 395 nm in solid state and was at 375 nm in liquid state, which show DNPE has obvious solution effects. Fluorescence quantum efficiency of 3,5-dimethyl-6-nitrile-pyridone is calculated by the value of 66.54%, which shows that pyridone derivatives have great application values both in fluorescent light-emitting materials and in blue-light emitting host materials. Key words: pyridone derivatives; fluorescent light-emitting materials; deep-blue; wide band-gap

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The fluorescence and afterglow properties of phosphor Ba4(Si3O8)2:Eu2+, Nd3+

Zhong-Fu YANG;

. 2014, 45(12-光电): 20-0.

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Long afterglow phosphors Ba3.88-x(Si3O8)2:0.12Eu2+,xNd3+ were synthesized by a solid state reaction. The crystal structure, excitation spectra, emission spectra, long afterglow decaying curves and thermoluminescence (TL) curves of samples were obtained in our work. The samples show a broad emission band of Eu2+ centered at 495 nm, and no new luminescent center appeared with Nd3+ co-doping. The fluorescence and afterglow intensities were both magnified obviously with Nd3+ co-doping, and the afterglow time prolonged. The optimal proportion of Nd2+ single doping is x=0.12, exhibiting a long-lasting phosphorescence lasting for 1 h visible to the naked eyes, more than 20 minutes with Eu2+ single doped. The analysis of TL with different waiting time shown that the TL peak shifts to the higher temperature with time prolongs, the half widths remain unchanged, the symmetry constant μg is about 0.52, the traps depth is 0.89 eV, and the process of releasing carriers is very close to the second order kinetics.

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Preparation and photocatalytic properties of Ag/TiO2 core-shell nanomaterial via a one-step solvothermal method

;Mu YANG ;

. 2014, 45(12-光电): 21-0.

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Ag/TiO2 core-shell nanofibers and nanoparticles were synthesized via one-step solvothermal method using tetrabutyl titanate (TBT) and AgNO3 as precursors. The structure and composition of these samples were characterized by SEM, TEM and XRD. The content of AgNO3, reaction temperature and dispersant agent polyacrylic acid (PAA) had an important influence on the morphology, structure and crystalline of the Ag/TiO2 composite materials. The effect of these factors on the photocatalytic activities was investigated and the reaction mechanism was proposed.

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A Low Damage Laser Annealing Process for Amorphous Silicon Thin Films with an Antireflective Film

;jiang gu ;

. 2014, 45(12-光电): 22-0.

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Using Si3N4 thin film as the antireflective layer low damage laser annealing process on amorphous silicon thin films was studied. XRD results show that the diffraction intensity of amorphous silicon thin film with an antireflective film increases first, then decreases with the increase of laser frequency. The antireflective samples show the highest diffraction peaks as annealing by the laser with frequencies from 10 to 15 Hz. For amorphous samples, the highest diffraction peaks appear when annealing by the laser of 20 Hz.SEM results show the reflective thin film can efficiently decrease the frequency of annealing laser frequencies, and the corresponding damage in the amorphous silicon thin films is reduced. It is confirmed that the annealing process with the antireflective thin film is an effective crystallization technics with low laser damage on amorphous silicon films.

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Study on the electronic structures and energy band properties of Al-doped β-Ga2O3

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. 2014, 45(12-光电): 23-0.

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First-principles plan-wave pseudopotential method is used to calculate the optimized parameters, electron density of states and energy band properties of Ga2-xAlxO3(x=0,0.5,1,1.5,2) alloys by doping Al into β-Ga2O3. It is found that β- Ga2-xAlxO3 is indirect wide-bandgap material, the bowing parameter is 0.452 eV for direct bandgap and 0.373 eV for indirect bandgap. The bandgap of β- Ga2-xAlxO3 is determined by O 2p state of valence band maximum and Ga 4s state of conduction band minimum. When the increase in Al concentration of Ga2-xAlxO3, the volumes decreased, the total energies and the bandgap increased, which is consistent with the experimental results.

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30 June 2014, Volume 45 Issue 12-光电