共查询到20条相似文献，搜索用时 15 毫秒
1.
The search for low‐cost thin‐film solar cells, to replace silicon multi‐crystalline cells in due course, calls for new combinations of materials and new cell configurations. Here we report on a new approach, based on semiconductor nanocomposites, towards what we refer to as the three‐dimensional (3D) solar‐cell concept. Atomic layer chemical vapor deposition is employed for infiltration of CuInS2 inside the pores of nanostructured TiO2. In this way it is possible to obtain a nanometer‐scale interpenetrating network between n‐type TiO2 and p‐type CuInS2. X‐ray diffraction, Raman spectroscopy, photoluminescence spectroscopy, scanning electron microscopy, transmission electron microscopy, and current–voltage measurements are used to characterize the nanostructured devices. The 3D solar cells obtained show photovoltaic activity with a maximum monochromatic incident photon‐to‐current conversion efficiency of 80 % and have an energy‐conversion efficiency of 4 %. 相似文献
2.
T. Cui J. Zhang J. Wang F. Cui W. Chen F. Xu Z. Wang K. Zhang B. Yang 《Advanced functional materials》2005,15(3):481-486
In this paper we describe the combined use of surface‐initiated atom transfer radical polymerization (ATRP) and a gas/solid reaction in the direct preparation of CdS‐nanoparticle/block‐copolymer composite shells on silica nanospheres. The block copolymer, consisting of poly(cadmium dimethacrylate) (PCDMA) and poly(methyl methacrylate) (PMMA), is obtained by repeatedly performing the surface‐initiated ATRP procedures in N,N‐dimethylformamide (DMF) solution at room temperature, using cadmium dimethacrylate (CDMA) and methyl methacrylate (MMA) as the monomers. CdS nanoparticles with an average size of about 3 nm are generated in situ by exposing the silica nanospheres coated with block‐copolymer shells to H2S gas. These synthetic core–shell nanospheres were characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA), diffuse reflectance UV‐vis spectroscopy, X‐ray photoelectron spectroscopy (XPS), and powder X‐ray diffraction (XRD). These composite nanospheres exhibit strong red photoluminescence in the solid state at room temperature. 相似文献
3.
Y.‐G. Guo J.‐S. Hu H.‐P. Liang L.‐J. Wan C.‐L. Bai 《Advanced functional materials》2005,15(2):196-202
A simple and versatile technique has been developed to prepare TiO2 and TiO2‐based composite (TiO2–CdS and TiO2–Au) nanotube arrays. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy‐dispersive X‐ray (EDX) analysis, X‐ray diffraction (XRD), thermogravimetric analysis (TGA), UV‐vis spectroscopy, and photoluminescence (PL) spectroscopy are used to characterize their morphology, structure, composition, and properties. The TiO2–CdS nanotubes contained many TiO2 and CdS quantum dots and exhibited a novel PL band in the blue‐wavelength range. The reported strategy will be useful for fabricating nanoparticle–nanoparticle composite nanostructure arrays, which are suitable for applications in catalysis, chemical sensors, nanoelectrodes, and nanodevices. 相似文献
4.
The silver ionic conductivity in heterogeneous systems of AgBr:Al2O3 and AgI:Al2O3 is highly enhanced by utilizing mesoporous Al2O3 as the insulating phase. The highest Ag+ conductivity of 3.1 × 10–3 Ω–1 cm–1 (at 25 °C) has been obtained for the AgI:Al2O3 composite with an Al2O3 volume fraction of 0.3. For AgBr:Al2O3, the enhancement of the conductivity is satisfactorily explained in the framework of the ideal space‐charge model, while in the case of AgI:Al2O3 stacking disorder is also considered to contribute to the ionic conductivity. 相似文献
5.
I.&#x;G. Giannakopoulos D. Kouzoudis C.&#x;A. Grimes V. Nikolakis 《Advanced functional materials》2005,15(7):1165-1170
The synthesis of a faujasite–Metglas composite material that can be used in gas‐sensing applications is presented. A continuous faujasite film was synthesized on a Metglas magnetoelastic strip using the secondary growth method. The ability of the new composite to remotely sense carbon dioxide in a nitrogen atmosphere at room temperature over a wide range of concentrations is demonstrated by monitoring the changes in the resonance frequency of the strip. The novel sensor combines the electromagnetic properties of the magnetoelastic material with the adsorption properties of the faujasite crystals. Experiments performed over a period of a few months showed that the composite sensor remained fully operational, thus indicating its long‐term stability. Furthermore, the present work demonstrates that a zeolite–Metglas composite can be used as a sensor of an analyte in a mixture as long as it adsorbs selectively larger amounts of the particular analyte than other compounds present in the mixture. 相似文献
6.
R. Takahashi Y. Yonezawa M. Ohtani M. Kawasaki K. Nakajima T. Chikyow H. Koinuma Y. Matsumoto 《Advanced functional materials》2006,16(4):485-491
Excellent crystallinity of material films and atomic control of their surface/interface, sufficient for the realization of their optimal physical properties, are technological premises for modern functional‐device applications. Bi4Ti3O12 and related compounds attract much interest as highly insulating, ferroelectric materials for use in ferroelectric random‐access memories. However, it has been difficult thus far for Bi4Ti3O12 films to satisfy such requirements when formed using vapor‐phase epitaxy, owing to the high volatility of Bi in a vacuum. Here, we demonstrate that flux‐mediated epitaxy is one of the most promising and widely applicable concepts to overcome this inevitable problem. The key point of this process is the appropriate selection of a multi‐component flux system. A combinatorial approach has led to the successful discovery of the novel flux composition of Bi–Cu–O for Bi4Ti3O12 single‐crystal film growth. The perfect single‐crystal nature of the stoichiometric Bi4Ti3O12 film formed has been verified through its giant grain size and electric properties, equivalent to those of bulk single crystals. This demonstration has broad implications, opening up the possibility of preparing stoichiometric single‐crystal oxide films via vapor‐phase epitaxy, even if volatile constituents are required. 相似文献
7.
R. Takahashi Y. Yonezawa M. Ohtani M. Kawasaki K. Nakajima T. Chikyow H. Koinuma Y. Matsumoto 《Advanced functional materials》2006,16(4)
Flux‐mediated epitaxy has been developed for ferroelectric Bi4Ti3O12 single‐crystal film growth, as shown on the inside cover. The key point is the selection of an appropriate flux material. A combinatorial high‐throughput screening technique reported by Matsumoto and co‐workers on p. 485 has led to the successful discovery of the novel flux composition, Bi–Cu–O, for Bi4Ti3O12 single‐crystal film growth. This flux‐mediated epitaxy is not limited to oxide epitaxy, but is also widely applicable to various promising materials for the realization of non‐Si‐based electronics, such as nitrides, carbides, and halides. Excellent crystallinity of material films and atomic control of their surface/interface, sufficient for the realization of their optimal physical properties, are technological premises for modern functional‐device applications. Bi4Ti3O12 and related compounds attract much interest as highly insulating, ferroelectric materials for use in ferroelectric random‐access memories. However, it has been difficult thus far for Bi4Ti3O12 films to satisfy such requirements when formed using vapor‐phase epitaxy, owing to the high volatility of Bi in a vacuum. Here, we demonstrate that flux‐mediated epitaxy is one of the most promising and widely applicable concepts to overcome this inevitable problem. The key point of this process is the appropriate selection of a multi‐component flux system. A combinatorial approach has led to the successful discovery of the novel flux composition of Bi–Cu–O for Bi4Ti3O12 single‐crystal film growth. The perfect single‐crystal nature of the stoichiometric Bi4Ti3O12 film formed has been verified through its giant grain size and electric properties, equivalent to those of bulk single crystals. This demonstration has broad implications, opening up the possibility of preparing stoichiometric single‐crystal oxide films via vapor‐phase epitaxy, even if volatile constituents are required. 相似文献
8.
S. Makhluf R. Dror Y. Nitzan Y. Abramovich R. Jelinek A. Gedanken 《Advanced functional materials》2005,15(10):1708-1715
Nanocrystalline particles of MgO were synthesized using microwave radiation in an ethylene glycol solution. The antibacterial activities of the MgO nanoparticles were tested by treating Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) cultures with 1 mg mL–1 of the nanoparticles. We have examined the importance of the size effect, pH, and the form of the active MgO species as a bactericidal agent. A clear size dependence of the nanoparticles is observed where the amount of eradicated bacteria was strongly dependent on the particle size. 相似文献
9.
A novel mesoporous‐nanotube hybrid composite, namely mesoporous tin dioxide (SnO2) overlaying on the surface of multiwalled carbon nanotubes (MWCNTs), was prepared by a simple method that included in situ growth of mesoporous SnO2 on the surface of MWCNTs through hydrothermal method utilizing Cetyltrimethylammonium bromide (CTAB) as structure‐directing agents. Nitrogen adsorption–desorption, X‐ray diffraction and transmission electron microscopy analysis techniques were used to characterize the samples. It was observed that a thin layer tetragonal SnO2 with a disordered porous was embedded on the surface of MWCNTs, which resulted in the formation of a novel mesoporous‐nanotube hybrid composite. On the base of TEM analysis of products from controlled experiment, a possible mechanism was proposed to explain the formation of the mesoporous‐nanotube structure. The electrochemical properties of the samples as anode materials for lithium batteries were studied by cyclic voltammograms and Galvanostatic method. Results showed that the mesoporous‐tube hybrid composites displayed higher capacity and better cycle performance in comparison with the mesoporous tin dioxide. It was concluded that such a large improvement of electrochemical performance within the hybrid composites may in general be related to mesoporous‐tube structure that possess properties such as one‐dimensional hollow structure, high‐strength with flexibility, excellent electric conductivity and large surface area. 相似文献
10.
S.&#x;Y. Choi B. Lee D.&#x;B. Carew M. Mamak F.&#x;C. Peiris S. Speakman N. Chopra G.&#x;A. Ozin 《Advanced functional materials》2006,16(13):1731-1738
A straightforward and reproducible synthesis of crack‐free large‐area thin films of 3D hexagonal (R‐3m) mesostructured nanocrystalline titania (meso‐nc‐TiO2) using a Pluronic triblock copolymer (P123)/1‐butanol templating system is described. The characterization of the films is achieved using a combination of electron microscopy (high‐resolution scanning electron microscopy and scanning transmission electron microscopy), grazing‐incidence small‐angle X‐ray scattering, in situ high‐temperature X‐ray diffraction, and variable‐angle spectroscopic ellipsometry. The mesostructure of the obtained films is found to be based upon a 3D periodic array of large elliptically shaped cages with diameters around 20 nm interconnected by windows of about 5 nm in size. The mesopores of the film calcined at 300 °C are very highly ordered, and the titania framework of the film has a crystallinity of 40 % being composed of 5.8 nm sized anatase crystallites. The film displays high thermal stability in that the collapse of the pore architecture is incomplete even at 600 °C. The accessible surface area of 3D hexagonal meso‐nc‐TiO2 estimated by the absorption of methylene blue is nearly twice as large as that of 2D hexagonal meso‐nc‐TiO2 at the same annealing temperature. 相似文献
11.
Z. Bian R.&#x;J. Wang W.&#x;H. Wang T. Zhang A. Inoue 《Advanced functional materials》2004,14(1):55-63
In this paper, we systematically report the preparation of carbon‐nanotube (CNT)‐reinforced Zr‐based bulk metallic glass (BMG) composites. The physical and mechanical properties of the composites were investigated. Compressive testing shows that the composites still display high fracture strength. Investigation also shows that the composites have strong ultrasonic attenuation characteristics and excellent wave absorption ability. The strong wave absorption implies that CNT‐reinforced Zr‐based BMG composites, besides their excellent mechanical properties, may also have significant potential for applications in shielding acoustic sound or environmental noise. 相似文献
12.
The photoresponse of ferroelectric smectic side‐chain liquid‐crystalline (LC) polymers containing a photoisomerizable azobenzene derivative as a covalently linked photochromic side group is investigated. By static measurements in different photostationary states, the effect of trans–cis isomerization on the material's phase‐transition temperatures and its ferroelectric properties (spontaneous electric polarization PS and director tilt angle θ) are analyzed. It turns out that the Curie temperature (transition SC* to SA) can be reversibly shifted by up to 17 °C. The molecular mechanism of this “photoferroelectric effect” is studied in detail using time‐resolved measurements of the dye's optical absorbance, the director tilt angle, and the spontaneous polarization, which show a direct response of the ferroelectric parameters to the molecular isomerization. The kinetics of the thermal reisomerization of the azo dye in the LC matrix are evaluated. A comparison to the reisomerization reaction in isotropic solution (toluene) reveals a faster thermal relaxation of the dye in the LC phase. 相似文献
13.
We report on the synthesis of wurtzite ZnS micrometer‐sized diskettes (including those lined up with ZnS nanowires) and ZnS nanoribbon arrays. Using ZnS powder as a source material, a vapor–solid growth based on a two‐stage temperature‐controllable thermal evaporation and condensation process is realized. Significant enhancement of luminescence compared to the ZnS source material is observed from these ZnS micro‐ and nanometer‐sized structures. The structures may serve as ideal model systems in the nano‐ to micrometer range for studying the optical and electronic properties of ZnS material. They can also be treated as prospective building blocks of two‐ and/or three‐dimensional arrays and are promising candidates for fabricating novel electronic and optoelectronic devices. 相似文献
14.
K. Roy&#x;Choudhury Y. Sahoo S. Jang P.&#x;N. Prasad 《Advanced functional materials》2005,15(5):751-756
A high‐performance hybrid polymeric photorefractive nanocomposite operating at the telecommunications wavelength of 1.34 μm is presented. The photorefractive nanocomposite is sensitized with PbS nanocrystals synthesized via a hot colloidal route. Photoconductivity experiments confirm and quantify the photocharge‐generation quantum efficiency of the nanocrystals. A pronounced two‐beam coupling effect at the operation wavelength is observed, leading to very high optical gains. Temporal evolution of the photorefractive growth process is also studied. 相似文献
15.
L. Liu Y.‐L. Lu L. He W. Zhang C. Yang Y.‐D. Liu L.‐Q. Zhang R.‐G. Jin 《Advanced functional materials》2005,15(2):309-314
The novel europium complex acrylato(1,10‐phenanthroline)bis(2‐thenoyltrifluoroacetonato)europium(III ) [Eu(tta)2(aa)(phen)] [Eu‐AAPhen; Htta = 4,4,4‐trifluoro‐1‐(2‐thienyl)‐1,3‐butanedione, Haa = acrylic acid, phen = 1,10‐phenanthroline], which combines the excellent fluorescence properties of [Eu(tta)3(phen)] and the reactivity of acrylic acid with radicals, has been synthesized. Various amounts of this complex (powder) are mixed with nitrile‐butadiene rubber (NBR) and peroxide to form uncured composites. These composites are vulcanized to obtain cured Eu‐AAPhen/NBR composites. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations show that the dispersion dimension for the cured composites is far finer than that for the uncured composites. Wide‐angle X‐ray diffraction (WAXD) experiments show that the crystallinity of Eu‐AAPhen in the composite decreases dramatically after the crosslinking process, implying that in‐situ reactions (including polymerization and grafting) of Eu‐AAPhen initiated by peroxide radicals should take place during the crosslinking of the NBR matrix with peroxide. The dispersion phase of the cured Eu‐AAPhen/NBR composite should be composed of nearly nanometer‐sized aggregates of poly(Eu‐AAPhen) and residual Eu‐AAPhen particles with reduced dimensions. The fluorescence properties of the cured composite are much better than those of the uncured one. 相似文献
16.
Y. Lee J. Lee C. J. Bae J.‐G. Park H.‐J. Noh J.‐H. Park T. Hyeon 《Advanced functional materials》2005,15(3):503-509
We have synthesized uniform and highly crystalline magnetite nanoparticles from the reaction of iron salts in microemulsion nanoreactors. The particle size can be controlled from 2 nm to 10 nm by varying the relative concentrations of the iron salts, surfactant, and solvent. Transmission electron microscope images of the nanoparticles reveal that they are very uniform in size distribution. Structural characterization using X‐ray diffraction and X‐ray magnetic circular dichroism shows that the nanoparticles are magnetite. The magnetic characterization of the nanoparticles showed that they are superparamagnetic at room temperature. Using a similar synthetic procedure, we have been able to synthesize nanoparticles of several mixed metal ferrites including cobalt ferrite, manganese ferrite, nickel ferrite, and zinc ferrite. 相似文献
17.
Y. Lee J. Lee C. J. Bae J.‐G. Park H.‐J. Noh J.‐H. Park T. Hyeon 《Advanced functional materials》2005,15(12):2036-2036
18.
J. Zhan Y.‐H. Tseng J.&#x;C.&#x;C. Chan C.‐Y. Mou 《Advanced functional materials》2005,15(12):2005-2010
Uniform nanorods of hydroxyapatite (HAP) with an unusual orthorhombic shape have been synthesized from homogeneous solutions of Ca2+ and HPO42– in the presence of gelatin and urea. The lengths of the nanorods are in the range of hundreds of micrometers, and the widths are about 100 nm. The HAP phase is generated by the transformation from its precursor phase of octacalcium phosphate (OCP), which has been monitored by X‐ray diffraction, NMR spectroscopy, scanning electron microscopy, and transmission electron microscopy. The rise in pH due to the decomposition of urea drives the OCP transformation to HAP. In the presence of gelatin, nanorods of OCP phase formed first and then transformed into the HAP phase, preserving the single‐crystal morphology. On the other hand, blade‐like OCP crystals form from the solution in the absence of gelatin. On increasing the pH of the solution, the large, blade‐like OCP crystals tend to crash into irregular, hexagonal HAP crystallites. A single‐crystal‐to‐single‐crystal topochemical transformation may be attributed to the evolution of HAP nanorods from the precursor OCP phase. This gives a strong indication as to the OCP to HAP transformation mechanism in the mineralization of biological apatite in tooth enamel and bone. 相似文献
19.
X. Liang X. Wang J. Zhuang Y. Chen D. Wang Y. Li 《Advanced functional materials》2006,16(14):1805-1813
Uniform magnetite, hematite, and goethite nanocrystals were prepared through an attractive method based on an oleic acid/alcohol/water system. By adjusting the synthetic parameters (base concentration, alcohol content, categories of alcohols, etc.), the controlled synthesis of uniform magnetite, hematite, and goethite nanocrystals can be easily achieved. Detailed investigations on the effect of the experimental parameters on the morphology of the final products and the phase transitions among the magnetite, hematite, and goethite phases were carried out. Finally, a method of doping other metal ions into magnetite was developed and the magnetic properties of magnetite doped with different metal elements were studied. 相似文献
20.
H.&#x;M. Yates M.&#x;E. Pemble E. Palacios‐Lidn F. García‐Santamaría I. Rodriguez F. Meseguer C. Lpez 《Advanced functional materials》2005,15(3):411-417
The growth of high‐quality stoichiometric indium phosphide by atmospheric pressure metal–organic chemical vapor deposition within thin‐film artificial opals has been optimized. The optical properties of these systems have been studied as a function of the filling fraction. A consistent behavior has been found which substantially differs from that of other common infilled opals. The evolution of the InP morphology seems to be strongly correlated with this anomalous photonic response. At the first infiltration stages, the growth leads to the formation of nanocrystallites that eventually, as the infiltration increases, coalesce in single‐crystalline grains of increasing size. The possibility to oxidize the material adds to its potential as a useful optical material. 相似文献