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The films of single-walled carbon nanotubes (SWCNTs) are a promising material for flexible transparent electrodes, which performance depends not only on the properties of individual nanotubes but also, foremost, on bundling of individual nanotubes. This work investigates the impact of densification on optical and electronic properties of SWCNT bundles and fabricated films. Our ab initio analysis shows that the optimally densified bundles, consisting of a mixture of quasi-metallic and semiconducting SWCNTs, demonstrate quasi-metallic behavior and can be considered as an effective conducting medium. Our density functional theory calculations indicate the band curving and bandgap narrowing with the reduction of the distance between nanotubes inside bundles. Simulation results are consistent with the observed conductivity improvement and shift of the absorption peaks in SWCNT films densified in isopropyl alcohol. Therefore, not only individual nanotubes but also the bundles should be considered as building blocks for high-performance transparent conductive SWCNT-based films.

Coloring silver for decorative purposes and for applying identification marks is an important task. In this paper, we consider a method for coloring silver surfaces using VIS plasmonic response in laser-induced nanoparticles (NPs). An analysis was made of the resulted morphology and chemical composition of nanoparticles obtained with nanosecond laser pulses. The dependence of the size and distribution of silver NPs on the laser exposure parameters is determined. The developed color palette was characterized using colorimetric coordinates.

An in situ microsynthesis of polyaniline films directly on a substrate was developed and considered from the viewpoint of conductivity as a key functional property. The microsynthesis was carried out in a reaction volume of 60 μL. The multi-analytical study of polyaniline samples obtained by in situ microsynthesis was performed. The effect of synthesis parameters (reaction time, temperature, and number of synthetic procedures on the same substrate) on the structure, morphology and conductivity was investigated. It was shown that the in situ microsynthesis allows for the formation of polyaniline films in the whole range of synthesis parameters chosen. The correlations between synthetic conditions, structural parameters and conductivity are discussed. The found correlations between FTIR parameters and conductivity can be considered as a promising tool for PANI characterization.

We present a comparative study of oxygen intercalation under polycrystalline and highly ordered graphene samples on the Co(0001) surface, which are relevant for magnetic applications. A comprehensi...

Attempts to improve solar cells efficiency touch all its constituents and are directly related to their fabrication protocols. While the most promising material platform for high efficiency photovoltaic devices is still III-V semiconductors, introduction of novel materials like single-walled carbon nanotubes (SWCNTs), which are characterized by unique combination of conductivity and transparency, might greatly yield the device performance. Here, for the first time, we present the results of the fabrication and characterization of a thin-film GaAs solar cell with a SWCNT top contact. We examine the contact between the SWCNT film and the semiconductor structure by means of the optical and electron beam-induced current techniques. The fabricated device demonstrates better performance, that is, increased power conversion efficiency from 10.6% to 11.5% when compared to the cell with the traditional metal contact grid, stemming from the enhanced photocurrent collection efficiency and low parasitic light absorption in the emitter layer. We envision future prospects to exploit the multifunctionality of the SWCNTs in fabrication of highly efficient photovoltaic devices including flexible solar cells.

A combined hollow cathode microsecond direct current pulsed glow discharge time-of-flight mass spectrometry (CHC μs-DC-PGD TOFMS) system has proved its efficiency for quantification; however, it has not been properly tested for the purpose of depth analysis until now, to the best of the authors' knowledge. The aim of the current study was to investigate the capabilities of this glow discharge source type for depth profiling. Special attention was paid to the alteration of depth resolution during the sputtering and the effect of discharge parameters on the crater shape in different types of solid samples. Both dielectric and conductive samples were tested, including: a Ni film on silicon, a Si film on borosilicate glass, and IR-reflective dielectric multilayer (mirror) coatings. Crater shapes were investigated after combined hollow cathode cell sputtering to ensure reliable profiling. For dielectric materials, including multilayer coatings, the deposition of a thin conducting layer (Ag or Ta) on the sample surface was demonstrated to result in reliable sputtering with adequate depth resolution of the profiling. This preliminary sample coating provided both the formation of required surface conductivity and reduction of the negative effect of atmospheric gases and water surface contamination at the beginning of sample sputtering. A silicon-coated borosilicate glass specimen was tested for potential quantitative profiling, showing promising results. The CHC μs-DC-PGD TOFMS system used was capable of analyzing the layers of varied thickness in the range from tens of nanometers to several micrometers. The depth resolution was 5 nm and 25 nm for conducting and dielectric layers, respectively.

Rubber materials are the key components of flexible optoelectronic devices, especially for the light-emitting diodes based on arrays of inorganic nanowires (NWs). This paper reports on polydimethylsiloxane-graft-polystyrene (PDMS-St) as a new flexible substrate of GaP NW array structures. The NWs were encapsulated by the newly introduced G-coating method to substitute the inefficient mainstream spin-coating. To further exploit the flexibility and the stretchability of the NW/PDMS-St structures, the ferrocenyl-containing polymethylhydrosiloxane was synthesized and successfully used as an electrode for the NWs. In order to make an alternative highly efficient transparent electrode, a new application of conductive single-walled carbon nanotubes was demonstrated. The novel materials and methods demonstrated unsurpassed mechanical stability of the fabricated flexible electronic devices.

Anisotropic gradient materials are considered as promising and novel in that they have numerous functional properties and are able to transform into hierarchical microstructures. We report a facile method of gradient inorganic thin film synthesis through diffusion-controlled deposition at the gas-solution interface. To investigate the reaction of interfacial phase boundary controllable hydrolysis by gaseous ammonium, an aqueous solution of FeCl3 and MnCl2 was chosen, as the precipitation pH values for the hydroxides of these metals differ gradually. As a result of synthesis using the gas-solution interface technique (GSIT), a thin film is formed on the surface of the solution that consists of Mn2+(Fe,Mn)23+O4 nanoparticles with hausmannite crystal structure. The ratio between iron and manganese in the film can be adjusted over a wide range by varying the synthetic procedure. Specific conditions are determined that allow the formation of a Mn-Fe mixed oxide film with a gradient of composition, morphology, and properties, as well as its further transformation into microscrolls with a diameter of 10-20 μm and a length of up to 300 μm, showing weak superparamagnetic properties. The technique reported provides a new interfacial route for the development of functional gradient materials with tubular morphology.

We report on single photon emitters for the green-yellow spectral range, which comprise a CdSe/ZnSe quantum dot placed inside a semiconductor tapered nanocolumn acting as a multimode nanoantenna. Despite the presence of many optical modes inside, such a nanoantenna is able to collect the quantum dot radiation and ensure its effective output. We demonstrate periodic arrays of such emitters, which are fabricated by focused ion beam etching from a II-VI/III-V heterostructure grown using molecular beam epitaxy. With non-resonant optical pumping, the average count rate of emitted single photons exceeds 5 MHz with the second-order correlation function g(2)(0) = 0.25 at 220 K. Such single photon emitters are promising for secure free space optical communication lines.

The majority of centrohelids bear external coverings consisting of organic spicules or siliceous scales. Cyst coverings are usually reinforced with additional layers of modified scales. The cyst wall of Raphidiophrys heterophryoidea has an unusual and complex structure. It consists of three different types of scales and includes the mosaic scale layer not known in other centrohelids. During excystment, the cyst wall fragments along the sutures of the mosaic layer. For other Raphidiophrys species, cyst coverings are not studied. The present paper describes a new Raphidiophrys species, R. elongata, belonging to the NC7 environmental clade. Trophozoites bore thin plate scales with reduced upper plate. Under starvation, cysts emerged in clonal cultures. Cyst coverings of R. elongata and R. heterophryoidea were studied in comparison with the use of FIB-SEM. Cyst wall of R. elongata was significantly thinner than in R. heterophryoidea and was formed with 3–5 layers of uniform overlapping scales. No mosaic scale layer was present. During excystment, trophozoite exited cyst shell through random fissure. Possible evolutionary events and driving forces behind the complication of cyst wall within Raphidiophrys were discussed.

In this work, we study ablation of silicon in distilled water under the action of laser pulses with nanosecond duration. The size distribution of produced particles depends on the laser processing parameters and therefore can be modified by the varying distance between laser pulses, laser fluence or pulse duration. The properties of fabricated nanostructures are investigated by scanning electron microscopy to acquire statistical information on nanoparticle sizes. These results can be promising for dielectric nanophotonics, photovoltaics or cancer treatment where relatively large spherical silicon particles are necessary.

Novel mixed-matrix membranes based on polyvinyl alcohol and its composites with carboxyfullerene were developed. Carboxyfullerene was simultaneously used as a modifier and a cross-linker for polyvinyl alcohol. The structural properties of the developed composites were studied by nuclear magnetic resonance, X-ray diffraction analysis, scanning electron microscopy, and sorption experiments. Thermal properties and stability were investigated by thermogravimetric analysis and differential scanning calorimetry. Surface features were studied by measuring the contact angles by water. The transport properties of the developed membranes were studied in ethanol-water mixtures separation by pervaporation (4.4–90 wt.% water in the feed) at different temperatures (22, 35, 50 °C). All membranes were selective with respect to water. The optimal transport properties were obtained for the PVA-carboxyfullerene (3.5 wt.%) membranes containing catalyst p-toluenesulfonic acid.

Fullerenol C60(OH)22–24 was incorporated into the polyamide (PA) selective layer to develop novel thin film nanocomposite (TFN) hollow fiber membranes for low molecular weight cut-off ultrafiltration. TFN membranes were fabricated via interfacial polymerization technique by alternately pumping fullerenol dispersion in triethylenetetramine (TETA) aqueous solution and isophthaloyl chloride solution in hexane through polysulfone hollow fiber membranes. Developed TFN PA/fullerenol membranes were investigated by FTIR, Raman spectroscopy, SEM, TEM, AFM, contact angle measurements and evaluated by determining the permeability, rejection and antifouling performance. Introduction of fullerenol to the PA skin layer was revealed to yield in the decrease of pure water flux and slight increase of lysozyme rejection which is attributed to the increase of the thickness of PA layer. Water contact angle of the skin layer was found to decrease sharply from 34° to 21° when the concentration of fullerenol increased up to 0.5 wt% in the TETA aqueous solution. Antifouling properties of the PA/fullerenol membranes were found to be superior to initial membrane. Fouling recovery ratio increased from 54% for the pristine membrane to 93% for the membrane with 0.5 wt% of fullerenol in the TETA aqueous solution. Irreversible fouling ratio was found to decrease from 38% to 6%, respectively. A correlation between surface properties and fouling behavior of TFN membranes upon increase of fullerenol concentration was established.

Efficient control over the grain boundaries (GBs) is a vital aspect in optimizing the graphene growth conditions. A number of methods for visualization of GBs were developed for graphene grown on weakly interacting surfaces. Here, we utilize oxygen intercalation to reveal GBs and study their morphology for graphene strongly bound to the cobalt surface. We demonstrate that upon the intercalation of oxygen, GBs in polycrystalline graphene become easily detectable due to graphene cracking and selective oxidation of the substrate, thus giving a direct insight into the graphene micro- and nanostructure by means of different electron microscopy methods, including scanning electron microscopy, photoemission microscopy and low-energy electron microscopy.

In this work, we studied a method of laser-induced coloration of metals, where small-scale spatially periodic structures play a key role in the process of color formation. The formation of such structures on a surface of AISI 304 stainless steel was demonstrated for the 1.06 µm fiber laser with nanosecond duration of pulses and random (elliptical) polarization. The color of the surface depends on the period, height and orientation of periodic surface structures. Adjustment of the polarization of the laser radiation or change of laser incidence angle can be used to control the orientation of the structures. The formation of markings that change their color under the different viewing angles becomes possible. The potential application of the method is metal product protection against falsification.

In this study, we show that Ag thin films (10 nm thickness) deposited on a glass substrate can be transformed into nanoparticles by laser-induced dewetting using a pulsed Nd:YAG laser operated at λ = 532 nm. The film could be entirely dewetted by a single pulse, and the required fluence was about 100 mJ/cm2. The properties of fabricated nanostructures are investigated by scanning electron microscopy and optical spectroscopy. The size distribution of produced particles and the absorption spectra of dewetted films were found. This process provides a facile and scalable method of forming metal nanoparticle arrays for plasmonic and other applications.

Platelet concentrates are used in clinic for therapy and prophylaxis of conditions associated with platelet deficiency or malfunction. The characteristics of platelet concentrates gradually change during pretransfusion storage, affecting their clinical effectiveness and the risk of adverse transfusion reactions. The presence of platelet-derived membrane vesicles is an important characteristic of platelet concentrates. Due to their functionality, changes in the number and molecular compositions of platelet-derived vesicles have major effects on the clinical properties of platelet preparations. The existence of different subpopulations of membrane vesicles requires analytical methods capable of providing information at the individual vesicle level. Such methods include flow cytometry and electron microscopy. However, conventional flow cytometry has certain limitations, since the diameters of many platelet-derived membrane vesicles are smaller than its detection limit. The use of classical scanning electron microscopy is also limited due to the requirement for coating with a layer of conductive material, which impedes the detection of small extracellular vesicles. Here, a combination of high-sensitivity flow cytometry and low-voltage scanning electron microscopy was used to increase sensitivity and resolution in the detection of nanosized objects present in platelet concentrates during storage. Apheresis platelet concentrates from eight healthy adult donors were investigated on days 2 and 7 of storage. Fractions of nanosized objects were obtained by differential centrifugation. Fluorophore-conjugated antibodies were used to detect marker-positive vesicles derived from platelets (CD41), red blood cells (CD235a), leukocytes (CD45), and endothelial cells (VEGFR2). Near-spherical objects with diameters ranging from 25 to 700 nm were observed by low-voltage scanning electron microscopy in platelet concentrates and its fractions. On day 7 of storage, objects with diameters of less than 100 nm were attached to and clustered near the terminal ends of pseudopod-like projections. High-sensitivity flow cytometry showed that during storage numbers of CD41(pos) vesicles elevated more than fivefold and numbers of marker-negative nanosized objects, which did not carry any of the investigated cell type-specific markers elevated more than twofold. Major changes in both CD41(pos) vesicles and marker-negative nanosized objects abundances were observed for objects with diameters around 100 nm bead equivalents. Overall, these results emphasized the importance of application of high-sensitivity methods for monitoring the characteristics of cell-derived nanosized objects during platelet concentrate storage.

A comprehensive picture of the nanosecond-laser generation of colloidal nanoparticles in liquids is nowadays the demand of their high-throughput industrial fabrication for diverse perspective biomedical, material science, and optoelectronic applications. In this study, using silicon as an example, we present a self-consistent experimental visualization and theoretical description of key transient stages during nanosecond-laser generation of colloidal nanoparticles in liquids: plasma-mediated injection of ablated mass into the liquid and driving the vapor bubble, finalized by the colloid appearance in the liquid. The explored fundamental transient stages envision the basic temporal and spatial scales, as well as laser parameter windows, for the demanded high-throughput nanosecond-laser generation of colloidal nanoparticles in liquids.

Novel dense and supported (polyacrylonitrile substrate) mixed matrix membranes based on biopolymer sodium alginate (SA), modified by Zr-MOFs were developed to improve pervaporation dehydration properties of a parent SA membrane. The following Zr-MOFs were synthesized and tested as modifiers: unmodified UiO-66 and modified UiO-66(NH2)-AcOH and UiO-66(NH2)-EDTA. Two kinds of mixed matrix membranes were developed: without additional treatment and cross-linked with calcium chloride. The synthesized Zr-MOFs nanoparticles and developed SA and SA-Zr-MOFs membranes were studied using Fourier-transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy, surface area measurement, atomic force microscopy, X-ray diffraction analysis, thermogravimetric analysis, and swelling experiments. Dense and supported membranes were tested for their transport properties in the pervaporation dehydration of isopropanol (12, 30 wt% water for the untreated membranes and 12–100 wt% water for the cross-linked membranes). The best transport properties (dehydration of water/isopropanol mixtures at 22 °C) were demonstrated by a supported cross-linked membrane, containing 15 wt% of UiO-66: permeation flux 0.47–3.38 kg/(m2h), water content in permeate 99.9-97.5 wt%.

Light is critical for art. It allows us to see color, and can itself be a tool for creating unique pieces of art and design. Here we demonstrate that a laser can be a multifunctional and effective tool for the creation of masterpieces, analogous to the process of an artist creating a canvas with classical paints and brushes. We investigate the interaction between focused laser irradiation and metallic surfaces and analyze the optical effects in thin oxide films for three main artistic operations: color making, multiple color changes, and erasing managed by a nanosecond laser. These processes are possible upon heating the material above the evaporation point and are proved to be dependent on the cooling rate, according to both experimental and theoretical results. Such an interference-based laser paintbrush could find applications in modern art and design.

Double-pulse femtosecond laser ablation of thin aluminum films and bulk aluminum counterintuitively demonstrated a strong (60–70%) raise of the thickness-dependent thresholds for inter-pulse delays of 20–200 ps, preventing material removal at above-threshold fluencies. Time-resolved optical pump-probe reflection and double-pump transmission studies were performed and confirmed the variation of the ablation threshold depending on the interpulse delay. To support the experimental measurements, the process of double-pulse laser ablation was modelled with the combined atomistic-continuum model. The applied model can describe the laser-induced non-equilibrium phase transition processes at atomic precision, whereas the effect of free carriers, playing a determinant role for the case of ultrashort laser pulses, is accounted for in the continuum. The simulations revealed the underlying pre-ablative laser-induced stress dynamics in the hot, acoustically relaxed Al melt, crucially sensitive to the second pump-pulse compressive pressurization. The results of theoretical and experimental study enable efficient dynamic all-optical control of ultrafast laser ablation.

We present a new approach for the preparation of electrocatalytically active carbonaceous coatings embedding bimetallic nanoparticles (NPs) - AgPt@C structures, on surfaces with 2D and 3D geometry such as glass covered with indium tin oxide (ITO) film and anodic aluminum oxide substrates, respectively. We provide extensive characterization of the deposited structures and demonstrate their performance towards the electrocatalytic glucose oxidation, one half-reaction of biofuel cells. We observe that a preliminary surface treatment of the porous alumina substrate is essential for a homogeneous laser-induced deposition of AgPt@C nanoparticles across the whole pore depth.

Gallium phosphide is an important material in terms of III-V semiconductors integration on Si. In this work we study photovoltaic properties of GaP:Be/GaNP (Eg ~ 2.0eV)/GaP:Si p-i-n heterostructure grown on Si (100) with GaP buffer by plasma-assisted molecular beam epitaxy. Correlation between the structural and optoelectronic properties of the fabricated device was studied by scanning and transmission electron microscopy (TEM), electron beam induced current (EBIC) and deep-level transient spectroscopy (DLTS) techniques. The I–V characteristic of the fabricated mesa diode demonstrates short circuit current of 2.2 mA/cm2 and open circuit voltage of 0.8 V. TEM studies of the epilayer structural properties demonstrate high density of antiphase domains in the n-doped GaP buffer layer; however, they found to be annihilated in dilute nitride layer, where mainly threading dislocations were formed. EBIC investigation shows that crystalline imperfections of the heterostructure leads to poor carriers transport affecting the energy conversion efficiency. We performed numerical modeling concerning presence of the structural defects and discuss their influence on the diode performance. The carried out study is the initial step on the way to development of the growth technique of the GaP-based dilute nitride direct bandgap materials on Si for photonic and photovoltaic applications.

We propose dielectric nanoantenna enhanced compact room-temperature operating hybrid photoconductive antennas (PCAs). Dielectric nanostructures in the PCA gap are deposited by focussed ion beam (FIB) and electro nanolithography methods. The resulting nanoantenna enhanced metasurfaces show 5-fold increase in pump radiation absorption, thus leading to THz generation enhancement.

Nanoporous iridium electrodes are prepared and electrochemically investigated towards the water oxidation (oxygen evolution) reaction. The preparation is based on ‘anodic’ aluminum oxide templates, which provide straight, cylindrical nanopores. Their walls are coated using atomic layer deposition (ALD) with a newly developed reaction which results in a metallic iridium layer. The ALD film growth is quantified by spectroscopic ellipsometry and X‐ray reflectometry. The morphology and composition of the electrodes are characterized by scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and X‐ray diffraction. Their catalytic activity is quantified for various pore geometries by cyclic voltammetry, steady‐state electrolysis, and electrochemical impedance spectroscopy. With an optimal pore length of L≈17–20 μm, we achieve current densities of J=0.28 mA cm−2 at pH 5 and J=2.4 mA cm−2 at pH 1. This platform is particularly competitive for achieving moderate current densities at very low overpotentials, that is, for a high degree of reversibility in energy storage.

International audience; We report here the growth and functional properties of silicon-based nanowhisker (NW) diodes produced by the vapor-liquid-solid process using a pulsed laser deposition technique. For the first time, we demonstrate that this method could be employed to control the size and shape of silicon NWs by using a two-component catalyst material (Au/Cu approximate to 601). During the NW growth, copper is distributed on the outer surface of the NW, whereas gold sticks as a droplet to its top. The length of NWs is defined by the total amount of copper in the catalyst alloy droplet. The measurements of the electrical transport properties revealed that in contact with the substrate, individual NWs demonstrate typical I-V diode characteristics. Our approach can become an important new tool in the design of novel electronic components.

Numerical simulation and EBIC measurements of GaAs-based solar cells with metal grid and CNT transport layer were performed. Influence of CNT transport layer properties on lateral current distribution was analyzed. In accordance with electron beam induced current measurements it was shown that CNT demonstrates perfect transport properties leading to good charge carrier’s collection.

We report on the heterogeneous nucleation of catalyst-free InAs nanowires on Si (111) substrates by chemical beam epitaxy. We show that nanowire nucleation is enhanced by sputtering the silicon substrate with energetic particles. We argue that particle bombardment introduces lattice defects on the silicon surface that serve as preferential nucleation sites. The formation of these nucleation sites can be controlled by the sputtering parameters, allowing the control of nanowire density in a wide range. Nanowire nucleation is accompanied by unwanted parasitic islands, but by careful choice of annealing and growth temperature allows to strongly reduce the relative density of these islands and to realize samples with high nanowire yield.

Selective-area remote epitaxy (SA-REpi) is demonstrated for fabricating the mechanically releasable position-controlled ZnO microrod (MR) arrays from the donor wafer in the arrayed form. Intaglio-p...