V. K. Nevolin

Fabrication of flexible transparent conductive coatings based on single-walled carbon nanotubes

We have proposed a method for large-scale growth of thin nanotube films from solution on the surface of flexible, transparent substrates. Uniform nanotube deposition was achieved through the preparation of a stable colloidal nanotube solution in an aqueous surfactant solution. We examined the effect of the number of deposition cycles on the morphology of the films and their optical and electrical characteristics. The results demonstrate that the optical transmittance of the films decreases linearly with increasing film thickness, whereas their resistance decreases quadratically, which corresponds to three-dimensional nanotube percolation in the films. With increasing film thickness, the sheet resistance of the films drops from 400 to 15 kΩ/□ and their transmittance decreases from 85 to 40%, respectively.

Flexible biological sensors based on carbon nanotube films

This paper presents the technique of forming flexible liquid sensors for biological applications based on carbon nanotube networks. We bend structures with a radius of curvature of 5 mm and the resistance change is no more than 8–10%, keeping the overall properties of the conductive coatings developed during multiple bends. We demonstrate the possibility of determining thrombin when biosensor structures are immobilized by specific aptamers.

Systematic features of the formation of semiconductor nanostructures using a focused ion beam

The systematic features of three-dimensional nanostructure fabrication using a focused ion beam are studied. The dependence of the depth of ion-beam-modified structures on the number of etching passes for the same ion dose is revealed with the aim of achieving accurate and predictable nanostructure formation. At the qualitative level, the effect of the thermodynamic parameters of Si, GaAs, and GaN semiconductors on the results of etching is analyzed.

Quasi-one-dimensional molecular transistors based on polyaniline and carbon nanotubes as electrodes

The technique for forming molecular quasi-one-dimensional conductors in an ac electric field, based on polyaniline molecules and multiwalled carbon nanotubes as supply leads, is proposed. The conductor diameter is ∼10 nm and its length is up to 150 nm. The presence of the field effect in the fabricated structures is demonstrated. The maximum carrier mobility is determined as 1.16 cm2/(V s).

Features of flexible transparent conducting films based on polyaniline-carbon nanotube composite

We propose a new concept in the formation of transparent conducting films based on single-walled carbon nanotubes (SWNTs) and polyaniline (PANI) on a flexible polyethylene naphthalate substrate. It is established that the resistance of SWNT-PANI composite films decreases to less than half as compared to pure nanotubes, while the transparency is retained. Mechanisms responsible for a change in the conductivity of composite molecular systems are discussed based on differences in the transport of charge carriers in nanotubes and the polymer with allowance for their interaction.

Prediction of the stability and electronic properties of carbon nanotori synthesized by a high-voltage pulsed discharge in ethanol vapor

An experimental technique for increasing the yield of carbon-nanotube nanotori using the modified arc synthesis method is proposed. New physical knowledge on the systematic features of the interrelation between the properties of nanotori and atomic-network topology are theoretically established for the first time. The experiments are performed based on new technology for synthesizing nanotori on nickel-catalyst particles by a high-voltage pulsed discharge in ethanol vapor and using atomic-force microscopy. Stability is predicted using an original procedure for calculating local atomic stresses. Simulation shows that the zigzag chirality corresponds to the most stable topology of nanotori. Using the tight binding method, it is shown that, depending on the chirality type, nanotori are divided into two classes, i.e., those with metal and semiconductor conductivity.

Effect of an Organic Molecular Coating on Control Over the Conductance of Carbon Nanotube Channel

It is shown that the coating of carbon nanotubes with molecules with a constant dipole moment changes the conductance of the tubes due to a variation in the structure of energy levels that participate in charge transport. The I–V characteristics of the investigated structures exhibit significant dependence of the channel conductance on the gate potential. The observed memory effect of conductance level can be explained by the rearrangement of polar groups and molecules as a whole in an electric field. The higher the dipole moment per unit length and the weaker the intermolecular interaction, the faster the rearrangement process is

On the high charge-carrier mobility in polyaniline molecular channels in nanogaps between carbon nanotubes

This study is devoted to the fabrication of molecular semiconductor channels based on polymer molecules with nanoscale electrodes made of single-walled carbon nanotubes. A reproducible technology for forming nanoscale gaps in carbon nanotubes using a focused Ga+ ion beam is proposed. Polyaniline molecules are deposited into nanogaps up to 30 nm wide between nanotubes by electrophoresis from N-methyl-2-pyrrolidone solution. As a result, molecular organic transistors are fabricated, in which the field effect is studied and the molecular-channel mobility is determined as 0.1 cm2/(V s) at an on/off current ratio of 5 × 102.

Narrow-Spectrum Photosensitive Structures Based on J-Aggregates of Cyanine Dyes

The fabrication processes for narrow-spectrum photosensitive structures based on J-aggregates of cyanine dyes are studied. Two technological approaches are proposed: the electrokinetic deposition of single J-aggregates in the planar electrode configuration and the fabrication of multilayer structures with a sensitive layer of cyanine dye J-aggregates and a transparent electrode made of a conductive carbon nanotube network on a flexible polyethylene naphthalate substrate.

Surface functionalization of single-layer and multilayer graphene upon ultraviolet irradiation

The process of oxidation of single-layer and multilayer graphene films upon ultraviolet irradiation of the structure in water vapor was studied. The systematic features and distinctions between changes in the topographic and optical properties of graphene films composed of different numbers of layers were established. The possibility of surface functionalization accompanied by modification of the energy structure of graphene was shown. Differences between single-layer and multilayer graphene films in the mechanisms of oxidation on ultraviolet irradiation are discussed and analyzed. Correlation of the topographic imperfections of the properties of the graphene material with its structural defects observed in Raman spectra was shown.