Andrei Sergeevich Toikka

Mr. Andrei Sergeevich Toikka

Photophysics LLC., Saint Petersburg, Sankt-Peterburg, Russia
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Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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31 January 2024 in Coatings
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ATAndrei Sergeevich Toikka
Andrei Sergeevich Toikka
MIMatwei Ilin
Matwei Ilin
Natalia KamaninaNatalia Kamanina
Natalia Kamanina
In many electro-optical devices, the conductive layer is an important key functional element. Among others, unique indium tin oxide (ITO) contacts take priority. ITO structure is widely used as the optical transparent and electrically conductive material in general optoelectronics, biosensors and electrochemistry. ITO is one of the key elements in the liquid crystal (LC) displays, spatial light modulators (SLMs) and LC convertors. It should be mentioned that not only the morphology of this layer structure but also the surface features play an important role in the study of the physical parameters of the ITO. In order to switch the surface properties (roughness, average tilt angle and surface free energy) of the ITO via the laser-oriented deposition (LOD) method, carbon nanotubes (CNTs) were implanted. In the LOD technique, the CO2 laser (λ = 10.6 μm, P = 30 W) with the control electric grid was used. The switching of the deposition conditions was provided via the varying electrical strength of the control grid in the range of 100–600 V/cm. The diagnostics of the surfaces were performed using AFM analysis and wetting angle measurements. The components of the surface free energy (SFE) were calculated using the OWRK method. The main experimental results are as follows: the roughness increases with a rise in the electric field strength during the deposition of the CNTs; the carbon nanotubes provide a higher level of the dispersive component of SFE (25.0–31.4 mJ/m2 against 22.2 mJ/m2 in the case of pure ITO); the CNTs allow an increase in the wetting angle of the 5CB liquid crystal drops from 38.35° to 58.95°. Due to the possibility of the switching properties of the ITO/CNT surfaces, these modifications have potential interest in microfluidics applications and are useful for the liquid crystal’s electro-optics.

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Natalia KamaninaNatalia Kamanina
Natalia Kamanina
ATAndrei Sergeevich Toikka
Andrei Sergeevich Toikka
Dmitry KvashninDmitry Kvashnin
Dmitry Kvashnin
Copper is important material that is widely applicable in the electric and electronic industries. Nevertheless, in some circumstances, it is highly desirable to improve its properties. Therefore, combination of materials of various composition and properties attracts scientific and industrial society. Here, the composite based on carbon nanotubes (CNTs) on a Cu surface was fabricated using laser-oriented deposition (LOD) technique and studied. Examination of the novel composite showed that its reflectance was decreased, the microhardness was increased, and wetting of the surface exhibited higher hydrophobicity. A molecular dynamic simulation showed that the penetration depth increases with nanotube diameter decrease and growth of the acceleration rate. Topography observations made via AFM images revealed a dense thin film with an almost-homogeneous distribution of CNTs, with several locations with irregular thickness addressing the different lengths of CNTs.

7 July 2022 in Materials
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Natalia KamaninaNatalia Kamanina
Natalia Kamanina
ATAndrei Sergeevich Toikka
Andrei Sergeevich Toikka
YBYaroslav Barnash
Yaroslav Barnash
PKPavel Kuzhakov
Pavel Kuzhakov
Dmitry KvashninDmitry Kvashnin
Dmitry Kvashnin
Due to difficulties in obtaining monomaterials, intensive research into the properties of ceramic compositions has been undertaken, along with developments to the properties of the compositions. These are not inferior to monomeric structures for a number of basic parameters. Among the different types of ceramics, magnesium fluoride and zinc sulfide occupy a special place due to their unique properties and specific applications. In this paper, we studied functional optoelectronics and modulating technique elements based on the advanced ceramics MgF2 and ZnS. The results of the transmittance spectral parameters and the contact angle estimation as well as an AFM analysis of the studied ceramics, both pure and structured with carbon nanotubes, are presented. We observed that the main characteristics of the studied materials with a surface modified by carbon nanotubes could be significantly changed when an innovative laser-oriented deposition method was applied. This method permitted the CNTs to be deposited in a vertical position on the material surface. The main features of the carbon nanotubes—such as the smaller value of the refractive index, the greater strength between the carbon atoms, and the effective surface—were taken into consideration. The analytical, quantum chemical, and experimental results of the studies of the changes in the basic physical parameters of the selected model of the inorganic matrices of the ceramics are given.

7 December 2021 in C
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Natalia KamaninaNatalia Kamanina
Natalia Kamanina
ATAndrei Sergeevich Toikka
Andrei Sergeevich Toikka
BVBulat Valeev
Bulat Valeev
Dmitry KvashninDmitry Kvashnin
Dmitry Kvashnin
It is known that a material’s volume and the surface structuring by the nanoparticles causes a significant change in the material’s basic properties. In this aspect, the structuration of the surface of semiconductors is of interest, because their wide potential application in optoelectronics can extend the products’ transparency, hardness, wettability, and other important parameters. This paper presents possible methods for the surface modification of zinc selenide and zinc sulfide when carbon nanotubes are deposited on the surface by the application of the laser-oriented technique. It also shows changes of the spectral, mechanical, and wetting characteristics of the considered materials. Using the molecular dynamic simulations, the possible process of the carbon nanotubes penetration into the considered surfaces is presented. The simulation results are partially supported by the obtained experimental data.

1 October 2021 in Liquid Crystals and their Application
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Natalia KamaninaNatalia Kamanina
Natalia Kamanina
ATAndrei Sergeevich Toikka
Andrei Sergeevich Toikka
GZG. N. Zvereva
G. N. Zvereva
PKP. V. Kuzhakov
P. V. Kuzhakov
YBYaroslav Barnash
Yaroslav Barnash
STS. A. Tarasov
S. A. Tarasov

14 March 2022 in Crystals
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Natalia KamaninaNatalia Kamanina
Natalia Kamanina
ATAndrei Sergeevich Toikka
Andrei Sergeevich Toikka
YBYaroslav Barnash
Yaroslav Barnash
Alla ZakAlla Zak
Alla Zak
Reshef TenneReshef Tenne
Reshef Tenne
Among the different methods for orienting liquid crystal (LC) molecules, adding nanoparticles into the matrix of the substrate material towards modifying its surface, is actively pursued. In this context, the influence of the nanoparticle content on the texture of the surface of polymer film used as the substrate for the LC orientation is of particular interest. Thus, in the current paper, WS2 nanotubes were used to dope the polyimide (PI) substrate-film in order to modify and control its surface morphology/roughness and properties. The modified organic surface structure is applied in order to achieve a new means for controlling the orientation of the LC molecules. This tool adds to the classical methods for controlling the orientation of the LC molecules, such as the display technique.