A new method for fabricating carbon nanotube‐conducting polymer (CNT‐CP) composite single nanowires is reported. The method developed is highly efficient, reliable, and economical because it obviates the time consuming process of template fabrication and the post‐synthesis task of positioning nanowires. Single nanowires with diameters of 50‐500 nm are fabricated between electrodes, self‐templated by dielectrophoresis and electropolymerization. Fabrication of an individually addressed nanowire array with cantilever electrodes on a microchip is demonstrated.
By means of first‐principles calculations we predict the stability of silicene as buckled honeycomb lattice on passivated substrates of group‐IV(111)1 × 1 surfaces. The weak van‐der‐Waals interaction between silicene and substrates does not destroy its linear bands forming Dirac cones at the Brillouin zone corners. Only very small fundamental gaps are opened around the Fermi level.
We present a computational study based on time‐dependent density functional theory of the optical absorption spectra of TiO2 nanowires sensitized with organic dye molecules. We concentrate on catechol and squaraine dyes. For those molecules, we compute adsorption geometries and energies and investigate the optical properties of the combined dye– nanowire system. We find that although the molecules have qualitatively different optical spectra in the gas phase, both lead to an enhancement of the absorption in the visible frequency range when adsorbed on a nanowire.
We report on solution‐processible polymer solar cells (PSCs) fabricated on a papery substrate using carton. Highly conductive PEDOT:PSS was used as a bottom anode and planarization layer, and a semi‐transparent top cathode was applied. This research could be an important approach to the development of all‐solution‐processible papery PSCs as well as paper electronics.
This Letter reports on the assembly on the tip of an optical fibre of a metamaterial film fabricated by a self‐assembly bottom‐up method, composed of silver nanowires embedded in an alumina matrix. By illuminating the film through the fibre in a reflection configuration, we observe experimentally the optical response of the metamaterial in agreement with theoretical predictions and interpreted as the excitation of surface plasmon‐polaritons in the cylindrical surface of the nanowires. These results pave the way for low‐cost optical fibre devices that incorporate metamaterial films.
Interaction between negatively charged Nafion® and a positively charged polybenzimidazole‐decorated carbon nanotube leads to the formation of an ionic complex with high charge density for proton conduction, which can lead to an improvement in transport properties. Here we investigate the high‐temperature and low‐humidity proton conductivity of this nanocomposite membrane as a potential membrane for fuel cell applications.
Write‐once–read‐many‐times memory (WORM) devices were fabricated using Ti/Au and Au as top contacts on ZnO thin films on Si. Electrical characterization shows that both types of WORM devices have large resistance OFF/ON ratio (R ratio), small resistance distribution range, long retention and good endurance. WORM devices with Au top contact have better performance of higher R ratio because of a larger work function of Au compared to Ti.
We study the spin ordering of a quantum dot defined via magnetic barriers in an interacting quantum spin Hall edge. The spin‐resolved density–density correlation functions are computed. We show that strong electron interactions induce a ground state with a highly correlated spin pattern. The crossover from the liquid‐type correlations at weak interactions to the ground state spin texture found at strong interactions parallels the formation of a one‐dimensional Wigner molecule in an ordinary strongly interacting quantum dot.
Quasi‐aligned molybdenum oxide nanowires are synthesized on silicon substrate by a thermal evaporation method, at a low temperature of 550 °C without using any catalyst. The diameter of these nanowires is about 100 nm, with steps in the top to form a sharp tip. The field emission measurement shows that these nanowires have strong electron field emission abilities, with high field enhancement factor and a relatively low turn‐on field of 2.16 V µm–1, suggesting that these molybdenum oxide nanowire arrays might be promising candidates as field emitters.
Light‐induced degradation of charge carrier lifetime was observed in indium‐doped silicon. After defect formation, an annealing step at 200 °C for 10 min deactivates the defect and the initial charge carrier lifetime is fully recovered. The observed time range of the defect kinetics is similar to the well known defect kinetics of the light‐induced degradation in boron‐doped samples. Differences between defect formation in boron‐ and indium‐doped silicon are detected and discussed. A new model based on an acceptor self‐interstitial ASi–Sii defect is proposed and established with experimental findings and existing ab‐initio simulations.
The crystallization process of mechanically alloyed Fe75Zr25 metallic glasses is investigated by means of both thermo‐magnetization and in situ neutron powder thermo‐diffraction experiments in the temperature range 300–1073 K. It was found that the crystallization takes place in a two‐step process, involving firstly the appearance of metastable Fe and Fe2Zr crystalline phases between 880 K and 980 K, and a subsequent polymorphic transformation into Fe3Zr above 980 K. These findings explain the anomalous magnetization vs. temperature behaviour on heating–cooling cycles.
We have shown that nitrophenyl groups may be added to the surface of few‐layer epitaxial graphene (EG) by the formation of covalent carbon–carbon bonds thereby changing the electronic structure and transport properties of EG from near‐metallic to semiconducting. In the present Letter we discuss the opportunities afforded by such chemical processes to engineer device functionality in graphene by modification of the electronic properties without physical patterning.
Dip‐coating of a colloidal suspension is investigated in situ with microbeam grazing incidence small‐angle X‐ray scattering. We focus on the real‐time monitoring of a vertical dip‐coating process yielding insights into structural changes during pattern formation of the thin film. With the selected configuration a fixed spot on the sample surface is probed and the structural information at the time the contact line passes this spot is obtained, hence revealing the structure at the vicinity of the flowing meniscus owing to the microfocused beam. After dip‐coating the morphology is analyzed with atomic force microscopy, yielding real space information about the arrangement of individual nanoparticles at the film surface.
Spin crossover compounds are considered to be a viable alternative for creating display, memory and switching devices due to the bistability of their magnetic, optical, mechanical and electrical properties. This Letter presents the study of the dielectric and transport properties of the [Fe(Htrz)2(trz)](BF4) (Htrz = 1H‐1,2,4‐triazole) complex in a wide temperature and frequency range. Our results reveal a singular behavior of the dielectric modulus upon the spin transition in conjunction with the switching of the conductivity between the high spin and low spin states.
We have fabricated multi‐peak and chromaticity‐stable top‐emitting white organic light‐emitting diodes (TEWOLEDs) using single blue emitter. Besides the intrinsic emission of blue emitter, the additional emission can be well realized by simply adjusting the thickness of hole transporting layer (HTL), thus modifying the optical cavity length to obtain different resonant wavelengths. The detailed variation process for multi‐peak spectra with the increase of HTL thickness is studied, which provides a guidance for the design of microcavity TEWOLEDs.
When a GaAs(001) substrate is heated up to 650 °C in a scanning electron microscope (SEM) vacuum chamber with vacuum range from 10–4 Torr to 10–5 Torr, real‐time SEM observation reveals microscale pits on GaAs substrate surface. The annealing process of GaAs substrate in vacuum causes excess evaporation of arsenic and accumulation of gallium as liquid droplets on the surface. As the function of electrochemical drills, the gallium droplets etch away GaAs beneath the surface to make microscale holes on GaAs substrate. With small amount of oxygen in the chamber acting as etching catalyst, gallium droplets etch GaAs much faster than in ultra‐high vacuum (UHV) MBE chamber. This process provides an easy technique to fabricate microscale pits on GaAs(001) surface.
A thermoplastic polymer solution was inkjet printed in a pre‐defined hexagonal pattern onto carbon fibre reinforced epoxy resin (CFRP), leading to a significant increase in strength, stiffness and toughness of the final aerospace grade compo‐site system. The approach consisted of depositing low‐viscosity polymer microdroplets having chemically and me‐chanically comparable properties to epoxy polymer, onto CFRP before curing and solidification. The microdroplets remained arrested between composite plies without direct contact with the neighbouring microdroplets ensuring preservation of the structural integrity of the new composite system after curing. The key to achieving this synergistic effect was in appropriately selected additive materials; however, the novel aspects also included the method itself, which enabled an accurate crack arrest mechanism.
Bulk polycrystalline La0.8Li0.2MnO3 is found to switch between a low‐resistance state and a high‐resistance state on thermal cycling. The low‐temperature, high‐resistance state exhibits strong electroresistance whereas the high‐temperature, low‐resistance state does not. The change in resistance between the two distinct states is of two orders of magnitude. It is proposed that the observed metastability may serve as the basis for resistive thermal‐switching devices.
