Hybrid organic–inorganic perovskites have emerged as promising materials for next-generation optoelectronic devices owing to their tunable properties and low-cost fabrication. We report the synthesis of 3D hybrid perovskites with monoethanolammonium cations. Specifically, we investigated the optoelectronic properties and morphological characteristics of polycrystalline films of hybrid perovskites MAxMEA1−xPbI3, which contain methylammonium (MA) and monoethanolammonium (MEA) cations. MAxMEA1−xPbI3 crystallizes in a tetragonal perovskite structure. The substitution of methylammonium cations with monoethanolammonium ions led to an increase in the lattice parameters and the bandgap energy. Energy level diagrams of the synthesized samples were also constructed. The bandgap of MA0.5MEA0.5PbI3 makes it a promising material for use in tandem solar cells. These polycrystalline films, namely MA0.5MEA0.5PbI3 and MA0.25MEA0.75PbI3 were fabricated using a one-step spin-coating method without an antisolvent. These films exhibit a uniform surface morphology under the specified deposition parameters. Within the scope of this study, no evidence of dendritic structures or pinhole-type defects were observed. All synthesized samples demonstrated photocurrent generation under visible light illumination. Moreover, using monoethanolammonium cations reduced the hysteresis of the I–V characteristics, indicating improved device stability.

The crystallization conditions from the solution play an important role in determining the morphology, phase composition, and photovoltaic properties of perovskite films. Post-processing of the obtained films can have a crucial role in increasing the grain size of perovskite and enhancing its crystallinity. It has been shown that the formation of crystal nuclei can be utilized to accelerate crystallization. In this case, crystallization occurs through the growth of seed crystals created in the solution, enabling the formation of relatively large crystals. For the deposition of CH3NH3PbI3 hybrid halide perovskite films from a solution of the perovskite in dimethylformamide, the spin coating technique was employed. Pre-crystallization was achieved by annealing the films at a temperature of 100 or 110 °C. The dissolution process involved adding a drop of dimethylformamide onto the substrate surface and allowing it to partially dissolve the perovskite film. Subsequently, residual solvent was removed through spin coating. The morphological analysis of the perovskite film surface after recrystallization at temperatures ranging from 80 to 130 °C was performed. The infrared transmission spectra of the obtained perovskite films were investigated, and their light absorption characteristics were studied through transmission spectra. The perovskite structure in the obtained films was confirmed by the peaks observed in the X-ray diffraction patterns. It has been shown that the photocurrent values for solar cells with perovskite films obtained by recrystallization are 15–20% higher than those of perovskite films obtained by traditional crystallization methods.

The principles of operation of the advanced resonant-reflectometric method for detecting GPS trackers and its advantages are described. It is shown that the detection of the re-radiated signal depends on parameters such as the power level and duration of the probing pulses, the frequencies of the probing pulses relative to the resonance frequency of the GPS tracker's input tract; the quality factor of the GPS tracker's input tract and the distance from the scanning antenna to the GPS tracker. A block diagram for experimental validation and determination of the optimal parameters for detecting the re-radiated signal is proposed, and a component base for its implementation is selected. A prototype module of a hardware-software complex based on the resonant-reflectometric method has been developed. The obtained experimental data confirmed the viability of the resonant-reflectometric method for detecting GPS trackers.

Penicillin antibiotics (PENs) play an important role in killing pathogenic bacteria. However, the residues of various penicillin antibiotics in milk gradually accumulate in the human body with the increase of milk intake, which causes direct harm to the human body. Aptamers can be used as recognition element of sensors. It is great significance to use broad-spectrum aptamers for simultaneous detection of PENs. In this study, we reported the screening and identification of DNA aptamers for PENs. The aptamers were screened by graphene oxidesystematic evolution of ligands by exponential enrichment (GO-SELEX). The broad-spectrum aptamers with high affinity and specificity were successfully obtained after 13 rounds of screening. The affinity and specificity of candidate aptamers were analyzed by a GO fluorescence competition method. Further sequence analysis revealed that a truncated 47 nt aptamer (P-11-1) had a higher affinity than the original 79 nt aptamer. The truncated aptamer P-11-1 was used as a recognition element, and an electrochemical aptasensor was prepared using gold nanoparticles (AuNPs) combined with ferroferric oxide-multi walled carbon nanotube (Fe3O4MWCNTs) complex. The results showed that the developed aptasensor achieved the simultaneous detection of PENs in milk samples across a concentration range of 2 nM-10,000 nM, achieving a limit of detection of 0.667 nM. This methodology provided a simple and sensitive new thinking for antibiotic multi-residue detection.

Studies of the self-organized growth of nanoporous anodic aluminum oxide (AAO) films and anodization parameters have been the subject of decades of research and various theories. At the same time, temperature, being one of the most important parameters in anodizing treatments of aluminum, has been investigated only as a function of electrolyte temperature. This paper presents the results of studying the growth kinetics and morphology of AAO formed by anodization processes in 1 M H2SO4 at different anode temperatures. The activation energy of ionic conductivity for AAO determined in this study was 0.41 eV for sulfuric acid, which was greater than the activation energy of 0.34 eV for oxalic acid. The effect of anode temperature on the pore diameter (dpore) and the interpore distance (Dinter) was studied. It was demonstrated that in the temperature range from 10 to 40 °C, the dpore and Dinter did not change with the anode temperature, with values equal to 12.5 ± 0.1 nm and 52.5 ± 0.2 nm, respectively. However, when the anode (aluminum) temperature was increased to 60 °C, the dpore increased to 16 nm. The results obtained show that by increasing the temperature of the anode from 20 to 40 °C, it is possible to increase the ionic conductivity of AAO and thus achieve a greater than threefold increase in the the rate of AAO growth, without altering the porous morphology of the anodic films.

This research focuses on the comparative analysis of effect of barium doping on the behavior of conductivity and impedance of organic-inorganic perovskite films, with an emphasis on their potential application in photovoltaic technology. The structural and electrical characteristics of CH3NH3PbI3 thin films with and without Ba are examined. Atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electron backscatter diffraction are used to investigate the morphology and structure of the samples. It was found that light-dependent transport in CH3NH3PbI3 thin films in the temperature range of 77–295 K leads to a tenfold decrease in the activation energy; this decreases from 160 – 280 meV to 10-20 meV as the temperature drops from 300 to 77 K. Light induces an increase in the activation energy at low temperatures, rising from 10 meV in darkness to 15-20 meV in light. CH3NH3PbI3 thin films doped with Ba stands out due to its notably higher photoluminescence intensity, suggesting an enhanced crystalline quality and a reduced defect density. Such characteristics are crucial for optimizing the efficiency of solar cells.

The crystallization conditions from the solution play an important role in determining the mor-phology, phase composition, and photovoltaic properties of perovskite films. Post-processing of the obtained films can have a crucial role in increasing the grain size of perovskite and enhancing its crystallinity. It has been shown that the formation of crystal nuclei can be utilized to accelerate crystallization. In this case, crystallization occurs through the growth of seed crystals created in the solution, enabling the formation of relatively large crystals. For the deposition of CH3NH3PbI3 hybrid halide perovskite films from a solution of the perovskite in dimethylformamide the spin coating echnique was employed. Pre-crystallization was achieved by heating films at a temperature of 100 or 110 °C. The dissolution process involved adding a drop of dimethylformamide onto the substrate surface and allowing it to partially dis-solve the perovskite for 30-40 seconds. Subsequently, residual solvent was removed through spin coating. The recrystallization process was carried out by heating films at the temperature range of 80 to 130 °C. The morphological analysis of the perovskite film surfaces after recrystallization at tem-peratures ranging from 80 to 130 °C was performed. The infrared transmission spectra of the obtained perovskite films were investigated, and their light absorption characteristics were studied through transmission spectra. The perovskite structure in the obtained films was con-firmed by the peaks observed in the X-ray diffraction patterns.

The results of studies of surface morphology and composition of copper coatings obtained by electrodeposition at high current densities are presented. It is shown that the copper deposits have a pyramidal growth of crystals with the formation of crystalline aggregates with distinct edges. Thus, the crystals were characterized by a homogeneous form over the entire surface area of the samples. Increasing the current density and, accordingly, overvoltage leads to an increase of the number of crystal nuclei, that causes formation of large crystalline aggregates due to the fusion of neighboring crystals. Electrodeposition conditions at high current densities make it possible to control the values of electrochemical and diffusion factors as well as the mechanism of nucleation and growth of copper crystals. The results obtained indicate that by varying the conditions of electrolysis, it is possible to obtain copper deposits with a specific microcrystalline structure.

A characteristic feature of the disordered pore growth at the initial stage of aluminum anodizing is the development of three large groups of pores: the major pores of larger diameter and two groups of minor pores of smaller diameter. The samples were obtained by the electrochemical oxidation of thin aluminum films (100 nm thick) on SiO 2 /Si substrates in a 0.3 M oxalic acid at 30 V at 5 °C–40 °C. According to SEM studies, the pore distribution by diameter for the films obtained at 20 and 40 °C has three distinct peaks at ca. 13.5, 17.2, and 20.3 nm. The ratio of the diameter of major pores to the diameter of minor pores of group 1 or group 2 is constant and approximately equal to 1.17 and 1.51, respectively. The generation of local compressive stress influences the development of porous morphology. The distribution of zones with high and low compressive stress levels inside hexagonal cells is shown, and their correlation with the porous morphology is confirmed. The generation of local stress and strains in the anodic alumina layer with a porous, cellular structure is associated with local areas with changes in the geometric properties on its surface.

The paper deals with the construction and design of devices operating by the method of resonance-reflectometric location to discover covert radio devices. The main stages of designing a prototype device operating by the method of resonance-reflectometric location are described. The materials of the analysis of modern types of SDR receivers and their main characteristics are presented. The choice of the SDR transceiver type based on the DDC technology (direct down conversion with frequency) is substantiated, in which the task to digitize the signal from the antenna is performed by the FTP with a high sampling rate. The results of the prototype device studies based on the SDR transceivers to search for covert radio devices are presented. The experimental results confirmed that the characteristics of modern SDR transceivers such as speed, sensitivity, and operating frequency bandwidth is fully consistent with the requirements for the design of resonant-reflectometer locator.

A characteristic feature of disordered porous anodic film growth at the initial stage of aluminum anodizing was revealed by varying the electrolyte type and anodizing voltage. The samples were obtained by the electrochemical oxidation of thin aluminum films (100 nm thick) on SiO2/Si substrates in a 0.3 M oxalic acid at 10–50 V and were studied by SEM. The ImageJ analysis of the images revealed the simultaneous development of two large groups of pores: major pores with a large diameter and minor pores with a smaller diameter. When anodizing in oxalic acid at 10–50 V, it has been shown that the ratio of the diameters of the major and minor pores remains constant and is about 1.17. Using a geometric model, we demonstrated that the centers of the minor pores are located inside the elementary hexagonal cell formed by the centers of the major pores. Moreover, our results are very close to the theoretical value of 2/√3. At the initial stage of disordered pore growth, the development of minor pores rather than major pores is not a random process and is determined by energy-efficient conditions for the development of pores inside the hexagonal cells formed by the major pores. The increase in compressive mechanical stress in the anodic film leads to an interruption in the development of such pores.

In the present work, the change of the electrical performance is investigated for two lead-free perovskite materials with novel iodide-based and bromide-based compositions under different exploitation conditions, such as light-induced stress, elevated temperatures and ultraviolet light exposure. The charge transport properties are studied in more detail by spectroscopic methods for the cell with the iodide layer due to its greater stability, aiming to understand the degradation mechanism. The results show that this perovskite exhibited excellent stability at UV exposure and acceptable stability at continuous illumination at 600 nm. The device is stable up to 55 °C, when the photovoltage drops. Beyond this threshold temperature, a phase change transition occurs related to traps formation and charge carriers escaping, which affects the photovoltage and it slightly increases.

The results of research on anodizing thin aluminum films 100 nm thick on SiO2–Si plates at 30 V in a 0.3 M aqueous solution of oxalic acid are presented. The effect of the electrolyte temperature on the morphology of porous anodic aluminum oxide (PAAO) films is studied. The pore diameter and interpore distance are determined by the computer analysis of the SEM images of the morphology of the anode films using the ImageJ software. The data obtained show that the pore diameter does not depend on the temperature of the electrolyte and the time of the process, but is determined only by the anodizing voltage. In the electrolyte temperature range of 5 to 40°C, the pore diameter of the PAAO films is 20 ± 0.5 nm, and the interpore distance is 77.7 nm. The research results indicate that a change in the temperature of the electrolyte, in contrast to the anodizing voltage, affects only the growth rate of the anode film, and not its porous morphology.

Poly(3,4- ethylenedioxythiophene):polystyrene sulfonate (PEDOT: PSS) is responsible for hole extraction efficiency and hole transport in the perovskite solar cell structure. The inclusion of PSS reduces the conductivity of the PEDOT films, which inhibits hole transport and results in a low photo current of the perovskite solar cell. In this work, an aniline solution was used as an additive in the PEDOT: PSS thin film to increase electrical conductivity. Two different methods were used to incorporate the additive: surface and volume treatment. The results show that the surface treatment with aniline solution can significantly increase the conductivity of PEDOT: PSS film. Moreover, the photoconversion efficiency of the perovskite solar cell with such a PEDOT: PSS layer is increased 1.5 times compared to the untreated one.

Among conductive polymers, PEDOT films find the widest application in electronics. For photovoltaic applications, studies of their optical properties, stability, and electrical conductivity are of greatest interest. However, the PEDOT:PSS transport layers, when used in photovoltaic cells, have a high electrical resistance, which prevents solar cells from increasing their efficiency. One of the promising ways to improve their electrical properties is the use of composite materials based on them, in which the conductivity can be increased by introducing various additives. In this work, conductive polymer films PEDOT:PSS (poly (3,4-ethylenedioxythiophene):polystyrene sulfonate acid) doped with a number of amines (Pentylamine, Octylamine, Diethylamine, Aniline with carbon nanotubes) were obtained and studied. It is shown that, depending on the concentration of dopants, the electrical conductivity of PEDOT:PSS films can be significantly improved. In this case, the light transmission of the films practically does not change. The process of improving the conductivity by treating the surface of the finished film with amines, followed by heat treatment, was studied. It is assumed that the improvement in conductivity is the result of the self-assembly of monolayers of organic molecules on the surface of the PEDOT:PSS film leading to its p-doping due to intermolecular interaction.

Herein, a novel electrochemical aptasensor using a broad-spectrum aptamer as a biorecognition element was constructed based on a screen-printed carbon electrode (SPCE) for simultaneous detection of aminoglycoside antibiotics (AAs). The ordered mesoporous carbon (OMC) was firstly modified on 2D Ti3C2 MXene. The addition of OMC not only effectively improved the stability of the aptasensor, but also prevented the stacking of Ti3C2 sheets, which formed a good current passage for signal amplification. The prepared OMC@Ti3C2 MXene functioned as a nanocarrier to accommodate considerable aptamers. In the presence of AAs, the transport of electron charge on SPCE surface was influenced by the bio-chemical reactions of the aptamer and AAs, generating a significant decline in the differential pulse voltammetry (DPV) signals. The proposed aptasensor presented a wide linear range and the detection limit was 3.51 nM. Moreover, the aptasensor, with satisfactory stability, reproducibility and specificity, was successfully employed to detect the multi-residuals of AAs in milk. This work provided a novel strategy for monitoring AAs in milk.

The results of studies on the effect of electrolyte temperature during anodizing of thin aluminum films on SiO 2 -Si plates on the morphology of porous anodic alumina (PAA) films are presented. The pore diameter and interpore distance were determined by computer analysis of SEM images of the morphology of the anode films. The data obtained showed that the pore diameter doesn’t depend on the temperature of oxalic acid solution and the time of the process, but is determined only by the anodizing voltage. For anodizing mode at 30 V with an electrolyte temperature in the range of 5-40 °C, the pore diameter of the PAA films was 20 ± 0.5 nm, and the interpore distance was about 77.7 ± 1.0 nm.

The modes of synthesis of TiO2 films with semiconducting properties by the method of electrochemical oxidation of Ti are proposed for use as an electronic transport layer of perovskite solar cells. To anodize the titanium film, the electrolyte based on a mixture of a 2 % aqueous solution of oxalic acid and a 1 % aqueous solution of sulfamic acids was used. The results obtained showed that Al and Ni have injection contacts to the anodic TiO2 films. Nanoscale titanium oxide films have low resistivity and rectilinear and symmetric I - V characteristic branches. Annealing of titanium oxide films leads to a significant decrease in the resistivity.

The article is devoted to the study of the photoluminescence of carbon-containing anodic alumina obtained in various electrolytes based on carboxylic (tartaric and oxalic) acids. We studied the emission and excitation spectra of luminescence, as well as the PL decay of nanostructured anodic alumina membranes. It is shown that such membranes exhibit photoluminescence (excitation wavelength 330 nm) in the wavelength range 350-600 nm with a maximum at 460 nm. They have two PL centers with maxima at 440 and 490 nm and lifetimes of 0.2 and 4.0 ns, respectively. It is shown that the PL peak at 440 nm can be related to the emission of COO– - ions, and the peak at 490 nm can be related to the PL of defects in partially oxidized amorphous carbon.