共查询到20条相似文献,搜索用时 351 毫秒
1.
Jongwook Kim Alexis de la Cotte Rodolphe Deloncle Samuel Archambeau Claudine Biver Jean‐Paul Cano Khalid Lahlil Jean‐Pierre Boilot Eric Grelet Thierry Gacoin 《Advanced functional materials》2012,22(23):4949-4956
Mineral liquid crystals are materials in which mineral's intrinsic properties are combined with the self‐organization behavior of colloids. However, the use of such a system for practical application, such as optical switching, has rarely been demonstrated due to the fundamental drawbacks of colloidal systems such as limited dispersion stability. Studying colloidal suspensions of LaPO4 nanorods, it is found that drastic improvement of colloidal stability can be obtained through a transfer of particles from water towards ethylene glycol, thus enabling the investigation of liquid crystalline properties of these concentrated suspensions. Using polarization microscopy and small‐angle x‐ray scattering (SAXS), self‐organization into nematic and columnar mesophases is observed enabling the determination of the whole phase diagram as a function of ionic strength and rod volume fraction. When an external alternative electric field is applied, a very efficient orientation of the nanorods in the liquid‐crystalline suspension is obtained, which is associated with a significant optical birefringence. These properties, combined with the high colloidal stability, are promising for the use of such high transparent and athermal material in electro‐optical devices. 相似文献
2.
We report a unique approach for producing one‐dimensional gold‐nanoparticle patterns with single‐particle resolution in which the linewidth is only limited by the particle size. In this approach, a focused electron beam was first utilized to generate a positive charge layer on a SiO2 surface. Biotinated DNA molecules attracted by these positive charges were subsequently used to grasp Au‐nanoparticles revealing the e‐beam exposure patterns. Due to repulsive force between Au colloidal particles, the particles in the single‐line patterns were orderly separated. We further show that the single‐line patterns hold potential in nano‐photonics and nano‐electronics. For the latter, we demonstrate that the line patterns can serve as a template for conductive nanowires of high or low resistance. While low resistance wires showed linear current–voltage characteristics with an extremely high maximum allowed current density, the high resistance wires exhibited charging effect with clear Coulomb oscillation behavior at low temperatures. This demonstrates that the technique is capable of producing interconnects as well as single‐electron‐transistors, and opens up possibilities for fabrication of integrated circuits. 相似文献
3.
除了通过改变胶体粒子半径及晶格常数来实现对光子带隙的调控方式之外,能否利用不同尺寸粒子的混合精确控制胶体光子晶体的显色行为是人们关注的一个重要科学问题。在分析Fe3O4@SiO2胶体光子晶体的带隙范围与介电常数、电磁波入射角度、晶格常数、颗粒尺寸、SiO2包覆层厚度的依赖关系的基础上,利用数值仿真手段对不同尺寸粒子混合得到的光子晶体的光传输特性进行了研究。结果发现,两种粒径的磁性胶体粒子按不同质量比混合后,其光子带隙位置始终落在两种粒径胶体粒子各自形成光子晶体的带隙位置之间,且随着大粒径颗粒掺杂比的增加,反射光谱逐渐红移。这一结果证明混色原理对胶体光子晶体仍然是适用的。该结果对研究胶体光子晶体结构色的新型调控方式具有重要的参考价值。 相似文献
4.
Polymerization‐Induced Colloidal Assembly and Photonic Crystal Multilayer for Coding and Decoding
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Photonic crystal (PC) films are prepared by precipitation of colloidal crystal seeds in supersaturated solution of particles, followed by crystal growth and structure fixing with photo‐polymerization. As the liquid monomer becomes a solid matrix, the highly concentrated particles are forced to precipitate into colloidal microcrystals in short time, and ‘polymerization‐induced colloidal assembly’ (PICA) is shown to be the major driving force to form colloidal crystals. PICA is intrinsically different from evaporation‐induced colloidal assembly, because the seed formation and crystal growth are separated into two independent steps, which makes the synthesis more flexible, controllable, and efficient. The PICA process is capable of quickly producing PC films with an ultra‐narrow bandgap, tunable thickness, and large size. Based on these characteristics and the blocking effect of the outer PC layer to the reflection signal of inner layer, a coding–decoding system is developed in which the film's composition and stacking sequence can be identified by its distinctive reflection spectrum. 相似文献
5.
Dong Choon Hyun Geon Dae Moon Eun Chul Cho Unyong Jeong 《Advanced functional materials》2009,19(13):2155-2162
The reversible nature of buckling is employed to repeatedly transfer colloids assembled in buckling patterns to flat surfaces. The cycle of colloidal loading–transfer–buckling is repeatedly carried out to fabricate the same colloidal patterns. The key to success is the reduction in the amplitude of the buckling patterns to a few nanometers as well as the recovery of initial buckling patterns after repeated stretching. The reduced buckling amplitude by poststretching or thermal annealing embosses the colloids assembled in the trenches of the buckling patterns, which enables the transfer regardless of the size, species, or layer thickness of the particles. This report demonstrates various transferred patterns composed of colloidal crystals, fluorescence hydrogel colloids, Au nanoparticles, and iron oxide magnetic particles. Since the process does not require surface modification of the colloids, it can be used to fabricate any colloidal patterns. 相似文献
6.
Zhiyuan Cheng Gianni Taraschi Matthew T. Currie Chris W. Leitz Minjoo L. Lee Arthur Pitera Thomas A. Langdo Judy L. Hoyt Dimitri A. Antoniadis Eugene A. Fitzgerald 《Journal of Electronic Materials》2001,30(12):L37-L39
The fabrication of 4 in, relaxed Si1−xGex-on-insulator (SGOI) substrates by layer transfer was demonstrated. A high-quality relaxed Si1−xGex layer was grown using ultrahigh vacuum chemical vapor deposition (UHVCVD) on 4 in. Si donor wafers. Thin Si−xGex film (x=0.2 or 0.25) was then transferred onto an oxidized Si handle wafer by bonding and wafer splitting using hydrogen
implantation. The resulting relaxed SGOI structures were characterized by transmission electron microscopy (TEM) and atomic
force microscopy (AFM). 相似文献
7.
D. M. Schaadt E. T. Yu S. Sankar A. E. Berkowitz 《Journal of Electronic Materials》2000,29(11):1299-1303
We have used scanning force microscopy to study localized charge injection and subsequent charge transport in discontinuous
Co/SiO2 multilayer structures. Charge was injected by applying a bias voltage pulse between a conductive proximal probe tip and the
sample. Electrostatic force microscopy was used to image charged areas, to determine quantitatively the amount of stored charge,
and to characterize charge transport. Charge was deposited controllably and reproducibly within areas ∼20–50 nm in radius
and an exponential decay in the peak charge was observed. The decay times were observed to be dependent on the nominal Co
film thickness and on the sign of the deposited charge, with longer decay times for positive charge than for negative charge.
These results are interpreted as a consequence of Coulomb-blockade effects, considering charge transport both within the Co
layer as well as from the Co layer into the Si substrate. 相似文献
8.
采用磁控溅射和退火技术制备出Au/SiO2纳米复合薄膜。利用扫描电子显微镜(SEM),X射线衍射(XRD)和原子力显微镜(AFM)对上述纳米复合薄膜进行了结构表征。实验结果表明,纳米复合薄膜的表面上均匀分布着直径在100~300nm的金纳米颗粒。金纳米颗粒的大小随着退火时间的增加而增大。用荧光光谱仪(PL)对薄膜的光致发光特性进行了研究。结果表明,在激发波长为325nm时,分别在525nm和560nm处出现两个发光峰;在激发波长为250nm时,在325nm处出现发光峰,这一发光峰可能与非晶SiO2的结构缺陷有关。 相似文献
9.
10.
S. Zhou Y. Liu W. Qiu Y. Xu X. Huang Y. Li L. Jiang D. Zhu 《Advanced functional materials》2002,12(1):65-69
A novel asymmetrically substituted dicyano‐tri‐tert‐butylphthalocyanine ((CN)2BuPc) with rectifying behavior has been synthesized. The morphology and conductive properties of (CN)2BuPc Langmuir–Blodgett (LB) films on mica and highly ordered pyrolytic graphite (HOPG) substrates were studied by atomic force microscopy (AFM) and scanning tunneling microscopy (STM), in air at 22 °C. The average area of each (CN)2BuPc molecule obtained from the AFM topography in situ is ca. 73.6 Å2, which is in good agreement with the result of ca. 74 Å2 obtained from the π–A isotherm curve of a LB film. This indicates that the molecules are standing edge‐on, tilted by 38° against the surface normal of the substrate. The conductive properties for the 7‐layer LB films of (CN)2BuPc were studied by STM with a tungsten tip. The asymmetric I–V curve revealed a type of rectifying behavior for a negative and a positive bias. A feature model of the intramolecular and intermolecular charge transfer is presented. It not only interprets electron transfer from electron‐donor to electron‐acceptor molecules via a molecular “bridge”, but also the tunneling effect through intermolecular charge transfer. 相似文献
11.
A. K. Sikder Ashok Kumar P. Shukla P. B. Zantye M. Sanganaria 《Journal of Electronic Materials》2003,32(10):1028-1033
Electroplated (EP) Cu films demonstrate a microstructural transition at room temperature, known as self-annealing, that involves
grain growth and texture changes. In this paper, we have investigated the annealing behavior of EP Cu films grown on a Cu
seed layer deposited on top of a TaN barrier layer. A grazing incident x-ray diffraction (GIXRD) pattern shows stronger x-ray
reflections form Cu (111) and (220) planes but weaker reflections from (200), (311), and (222) planes in all the EP Cu samples.
Nanoindentation was performed on all the samples using the continuous stiffness measurement technique. The elastic modulus
varied from 121 GPa to 132 GPa, while the hardness varied from 1 GPa to 1.3 GPa, depending on the annealing conditions. The
surface morphology and roughness of the Cu films were characterized using atomic force microscopy (AFM). The tribological
properties of the copper films were measured using the Bench Top chemical mechanical polishing (CMP) tester (CETR, Inc., Campbell,
CA). Nanoindentation was performed on the samples after CMP, and an increase in hardness and modulus was observed. This may
be attributed to the work hardening of the Cu films during CMP. 相似文献
12.
Fang Huang Xiangxin Liu Wenjing Wang 《Progress in Photovoltaics: Research and Applications》2015,23(3):319-330
In this work, we report significant characteristics of nanodipole solar cells that would facilitate the understanding of the mechanism underlying the nanodipole photovoltaic effect. A CdS–CdTe pseudobinary system underwent phase segregation during high‐temperature CdCl2 treatment in a N2 atmosphere, giving convincing evidence to prove the existence of wurtzite CdS0.956Te0.044 nanodipoles embedded in zinc blende CdS0.04Te0.96. On the microscale, a strong synchronous in‐plane piezoresponse by wurtzite CdS0.956Te0.044 was observed using piezoelectric force microscopy in the vertical and lateral modes. Further, it was observed that a piezoresponse and analogous electric hysteresis existing at the grain boundaries varied with an external direct current electrical field; this phenomenon is considered to contribute significantly to the hysteresis behavior of photovoltage. In addition, high‐resolution transmission electron microscopy analysis indicated the formation of hexagonal CdS0.956Te0.044 particles in the film. On the macroscale, the photovoltage of a CdS nanodipole device with a symmetric structure was found to be tunable and became stable after the application of a direct current field. This feature of tunable photovoltage cannot be explained by the classical theory of junction devices. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
13.
M.C. LeMieux Y.‐H. Lin P.D. Cuong H.‐S. Ahn E.R. Zubarev V.V. Tsukruk 《Advanced functional materials》2005,15(9):1529-1540
We have characterized the morphology and nanomechanical properties of surface‐grafted nanoscale layers consisting of Y‐shaped binary molecules with one polystyrene (PS) arm and one poly(acrylic acid) (PAA) arm. We examined these amphiphilic brushes in fluids (in‐situ visualization), and measured their microtribological characteristics as a function of chemical composition. Atomic force microscopy (AFM)‐based nanomechanical testing has shown that nanoscale reorganization greatly influences the adhesion and elastic properties of the nanoscale brush layer. In water, a bimodal distribution of the elastic modulus, arising from the mixed chemical composition of the topmost layer, is observed. In contrast, the top layer is completely dominated by PS in toluene. As a result of this reorganization, the Y‐shaped‐brush layer exhibits a dramatic variation in the friction and wear properties after exposure to different solvents. Unexpectedly, the tribological properties are enhanced for the hydrophilic and polar, PAA‐dominated, surface, which shows a lower friction coefficient and higher wear stability, despite higher adhesion and heterogeneous surface composition. We suggest that this unusual behavior is caused by the combination of the presence of a thicker water layer on the PAA‐enriched surface that acts as a boundary lubricant and the glassy state of the PAA chains. 相似文献
14.
V. G. Talalaev A. V. Senichev B. V. Novikov J. W. Tomm T. Elsaesser N. D. Zakharov P. Werner U. Gösele Yu. B. Samsonenko G. E. Cirlin 《Semiconductors》2010,44(8):1050-1058
Methods of optical spectroscopy and electron microscopy have been used to study tunnel-injection nanostructures the active
region of which consisted of an upper In0.15Ga0.85 As quantum-well layer and a lower layer of In0.6Ga0.4As quantum dots as a light emitter; both layers were separated by a GaAs barrier layer. Deviations from the semiclassical
Wentzel-Kramers-Brillouin model are observed in the dependence of the tunneling time on barrier’s thickness. Reduction of
the transfer time to several picoseconds at a barrier thickness smaller than 6 nm is accounted for by formation of InGaAs
nanobridges between tops of quantum dots and the quantum-well layer; the nanobridges include those with their own hole state.
The effect of an electric field induced by tunneling on the carriers’ transfer time in a tunnel-injection nanostructure is
taken into account. 相似文献
15.
Maxime Paven Regina Fuchs Taro Yakabe Doris Vollmer Michael Kappl Akiko N. Itakura Hans‐Jürgen Butt 《Advanced functional materials》2016,26(27):4914-4922
Surfaces with self‐cleaning properties are desirable for many applications. Conceptually, super liquid‐repellent surfaces are required to be highly porous on the nano‐ or micrometer scale, which inherently makes them mechanically weak. Optimizing the balance of mechanical strength and liquid repellency is a core aspect toward applications. However, quantitative mechanical testing of porous, super liquid‐repellent surfaces is challenging due to their high surface roughness at different length scales and low stress tolerance. For this reason, mechanical testing is often performed qualitatively. Here, the mechanical responses of soot‐templated super liquid‐repellent surfaces are studied qualitatively by pencil and finger scratching and quantitatively by atomic force microscopy, colloidal probe force measurements, and nanoindentation. In particular, colloidal probe force measurements cover the relevant force and length scales. The effective elastic modulus, the plastic work Wplastic and the effective adhesive work Wadhesive are quantified. By combining quantitative information from force measurements with measurements of surface wetting properties, it is shown that mechanical strength can be balanced against low wettability by tuning the reaction parameters. 相似文献
16.
Photoreduced Graphene Oxide as a Conductive Binder to Improve the Water Splitting Activity of Photocatalyst Sheets
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zhenhua Pan Takashi Hisatomi Qian Wang Shanshan Chen Akihide Iwase Mamiko Nakabayashi Naoya Shibata Tsuyoshi Takata Masao Katayama Tsutomu Minegishi Akihiko Kudo Kazunari Domen 《Advanced functional materials》2016,26(38):7011-7019
Photocatalyst sheets consisting of H2 evolution photocatalyst (HEP) and O2 evolution photocatalyst (OEP) particles applied to an underlying conductive layer show promise with regard to promoting efficient and scalable water splitting. One of the most important challenges in enhancing the performance of such systems is establishing efficient charge transfer between photocatalyst particles that are often thickly stacked on the conductive layer. In this study, reduced graphene oxide (RGO) is investigated as an additional solid mediator to the conductive layer to bridge particulate photocatalysts and thus ensure effective charge transfer. Photocatalyst sheets made of RhCrOx/LaMg1/3Ta2/3O2N as the HEP and BiVO4:Mo as the OEP are applied to an Au layer together with RGO. The activity of this system is 3.5 times greater following the incorporation of the RGO. Charaterization analyses reveal that RhCrOx/LaMg1/3Ta2/3O2N particles tens of nanometers in size are fixed on larger, micrometer‐sized, BiVO4:Mo particles by RGO photoreduced from GO in situ. The RGO facilitates charge transfer between particles that are distant from the underlying Au layer and thus involves more photocatalyst particles in the water splitting reaction. It is concluded that the incorporation of conductive materials into the photocatalyst particle layer can effectively enhance the water splitting activity of photocatalyst sheets. 相似文献
17.
采用激光预置熔覆法,通过在FeCSiB合金粉末中添加一定比率的强碳化物形成元素Zr,在中碳钢基体上制备原位析出的颗粒增强铁基复合材料表层。利用光学显微镜、场发射电子扫描显微镜(能谱仪)和金相组织分析系统,对熔覆层显微组织、硬质颗粒的成分及其分布规律进行了观察与分析。其显微组织特征是树枝状的先共晶奥氏体分布在共晶基体上的亚共晶介稳组织;奥氏体在随后的冷却过程中转变为马氏体;熔覆层与基体成良好的冶金结合。熔覆层内析出的硬质颗粒是以ZrC为主的复合碳化物,主要分布在枝晶内与枝晶间;单道搭接熔覆层颗粒的体积分数分别为1.96%、2.2%~3.84%;显微硬度值在800HV0.2~1100HV0.2之间。 相似文献
18.
《Organic Electronics》2014,15(4):835-843
TiO2 sols synthesized with a facile solution-based method were used as a buffer layer between the active layer and the cathode Al in conventional structure polymer solar cells (PSCs). Using transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD) and atomic force microscopy (AFM), the morphological and crystallographic properties of synthesized TiO2 nanoparticles (TiO2 NPs) as well as the buffer layer were studied in detail. It was observed that by increasing H2O in the process of peptization both the crystallinity and particle size of TiO2 NPs were enhanced, while the particles in sol showed a narrower size distribution conformed by dynamic light scattering. Inserting TiO2 NPs as a buffer layer in conventional structure PSCs, both the power conversion efficiency (PCE) and stability were improved dramatically. PSCs based on the structure of ITO/PEDOT:PSS/P3HT:PCBM/TiO2 NPs/Al showed the short-circuit current (Jsc) of 12.83 mA/cm2 and the PCE of 4.24%, which were improved by 31% and 37%, respectively comparing with the reference devices without a TiO2 buffer layer. The stability measurement showed that PSC devices with a TiO2 NPs buffer layer could retain 80% of the original PCEs after exposed in air for 200 h, much better than the devices without such a buffer layer. The effect can be attributed to the protection by the buffer layer against oxygen and H2O diffusion into the active layers. The observations indicate that TiO2 NPs synthesized by facile solution-based method have great potential applications in PSCs, especially for large-area printed PSCs. 相似文献
19.
J. Scott Niezgoda Amy Ng Jonathan D. Poplawsky James R. McBride Sandra J. Rosenthal 《Advanced functional materials》2016,26(6):895-902
The delicate influence of properties such as high surface state density and organic–inorganic boundaries on the individual quantum dot electronic structure complicates pursuits toward forming quantitative models of quantum dot thin films ab initio. This report describes the application of electron beam‐induced current (EBIC) microscopy to depleted‐heterojunction colloidal quantum dot photovoltaics (DH‐CQD PVs), a technique which affords one a “map” of current production within the active layer of a PV device. The effects of QD sample size polydispersity as well as layer thickness in CQD active layers as they pertain to current production within these PVs are imaged and explained. The results from these experiments compare well with previous estimations, and confirm the ability of EBIC to function as a valuable empirical tool for the design and betterment of DH‐CQD PVs. Lastly, extensive and unexpected PbS QD penetration into the mesoporous TiO2 layer is observed through imaging of device cross sections by energy‐dispersive X‐ray spectroscopy combined with scanning transmission electron microscopy. The possible effects of this finding are discussed and corroborated with the EBIC studies on similar devices. 相似文献
20.
《Solid-state electronics》2006,50(7-8):1461-1465
In this paper the preliminary results of incorporating a novel active layer into a GaN light emitting diode (LED) are discussed. Integration of colloidal CdSe quantum dots into a GaN LED active layer is demonstrated. Properties of p-type Mg doped overgrowth GaN are examined via circular transmission line method (CTLM). Effects on surface roughness due to the active layer incorporation are examined using atomic force microscopy (AFM). Electroluminescence of LED test structures is reported, and an ideality factor of n = 1.6 is demonstrated. 相似文献