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.

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.

A single-stage centrifugation method is used for the precipitation and crystallization of a solution of a hybrid halide perovskite compound of the CH3NH3PbI3 composition. The perovskite films are annealed in the temperature range of 80–140°C, during which the excess of the N-methylpyrrolidone solvent was removed by evaporation. The X-ray phase analysis of the synthesized perovskite layer is carried out. The morphology of the surface of the layers after crystallization and the transmission spectra in the optical range are studied. The experiments and research results showed that the optimal temperature regime for the formation and crystallization of lead triiodide methylammonium perovskite films is 100–110°C. The perovskite layers obtained in these processing regimes have a surface morphology with a uniform granular crystal structure and are highly uniform. Moreover, in solar cells based on perovskite-like CH3NH3PbI3 structures with an annealing temperature of 100–110°C, the short-circuit currents reached 16.0 mA/cm2. At the same time, at annealing temperatures of perovskite layers above 120°С, the maximum value of the short-circuit currents did not exceed 14.0 mA/cm2.

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.

Для осаждения и кристаллизации раствора гибридного галогенидного соединения состава CH 3 NH 3 PbI 3 , обладающего структурой перовскита использовался метод одноступенчатого центрифугирования. Процесс отжига слоев со структурой перовскита проводился в диапазоне температур 80–140°С, во время которого происходило удаление избытка растворителя N -метилпирролидона за счет испарения. Проведен рентгенофазовый анализ синтезированного слоя. Изучены морфология поверхности слоев после кристаллизации и спектры пропускания в оптическом диапазоне. Эксперименты и результаты исследований показали, что оптимальным температурным режимом при формировании и кристаллизации пленок перовскита трийодидметиламмоний свинец являлась температура 100–110°С. Слои со структурой перовскита, полученные в таких режимах обработки, имели морфологию поверхности с равномерной зернистой структурой кристаллов и характеризовались высокой однородностью. Более того, в солнечных ячейках, полученных на основе перовскитоподобных структур CH 3 NH 3 PbI 3 с температурой отжига 100–110°С токи короткого замыкания достигали значений 16.0 мА/см 2 . В тоже время при температурах отжига слоев со структурой перовскита выше 120°С максимальное значение токов короткого замыкания не превышало 14.0 мА/см 2 .

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.

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.

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.

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 work is devoted to the study of the porous structure formation of anodic alumina films at the initial stage of aluminium anodizing. SEM images of the surface morphology of the oxalic acid anodic films were analyzed. It was shown that at the initial stage, both major and minor pores are formed, the diameter ratio of which is about 1.16 and does not depend on the anodizing voltage. The results obtained indicate that the minor pores in the anodic films are located inside hexagonal cells composed of the major pores.

The results of studies of electronic conductivity in annealed films of porous anodic alumina obtained in phosphoric acid are presented. Polarization experiments were carried out for an electrolyte-anodic alumina -aluminum structure in a barrier type electrolyte in the anodic potential sweep mode. It is shown that the initial section of the current curve is described by the theory of a current by a limited space charge for the case of electron traps exponentially distributed over energies in the energy gap of anodic alumina. For porous anodic alumina formed in phosphoric acid, it was experimentally determined that the characteristic energy of the distribution of traps in the band gap of anodic alumina is 0.23 eV.

Introduction. For controlled thermal management of power electronics devices, an important task is to increase the efficiency of heat removal from active components. Aim. To introduce a new approach to placing a linear contact-type heat source on the surface of thin samples in order to study the features of propagation of heat fluxes in oxide substrates from materials with different thermal conductivities. Methods and materials. The paper presents the results of studies of the propagation of heat fluxes in oxide substrates with different thermal conductivity (glassceramic and aluminum oxide ceramic - polycor). To generate the heat flux, a linear heat source was used, for which an electrically conductive carbon fiber was applied. Results. Thermograms and temperature distribution profiles were obtained at different periods of heating time on the surface of the substrate with a heating element and on its reverse side. It was shown that the placement of the linear heat source, implemented using an electrically conductive carbon filament, on the surface of the studied samples and time monitoring of thermograms from two opposite surfaces of the samples allowed to obtain data for evaluating the thermal properties of oxide substrates. The distribution of the heat flux in a homogeneous material near the generation point had the form of a cone of a heat pipe with a base on the surface with a heat source. The thermal cone for an aluminum oxide ceramic substrate had a larger angle of inclination than that in the case of glassceramic. Conclusion. The results obtained allowed to propose a method for reduction of thermal resistance of a heatconducting substrate by creating conditions for increasing the area of heat-conducting section.