This study investigates the structural, electrical properties, and impedance characteristics of thin graphite-like carbon films deposited by electron-beam evaporation and annealed in vacuum. Raman spectroscopy reveals that the films consist mainly of sp2-hybridized carbon with graphite-like clusters of approximately 9.5 nm. Current-voltage measurements indicate space-charge-limited conduction and trap states. Impedance spectroscopy shows two overlapping relaxation processes, modeled with an equivalent circuit of two parallel branches with resistive and constant phase elements. The calculated effective capacitances were Ceff 1 = 4.09*10-9 F and Ceff 2 = 7.87*10-8 F, with corresponding relaxation times of approximately tau eff 1 = 1.12*10-6 sand tau eff 2 = 3.6* 10-5 s respectively. The observed low-frequency nonlinear dielectric response exhibits strong dependence on the applied DC bias, leading to a pronounced decrease in the real part and increase in the imaginary part of the dielectric permittivity. This bias-controlled behavior suggests great potential for implementation in tunable capacitors and frequency-dependent energy storage components. The obtained results demonstrate the interplay between conduction and polarization processes in nanostructured carbon films and validate the relevance of the cluster-based structural model.

Detonation nanodiamonds (DNDs) were incorporated into poly(3,4ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) films to investigate their influence on the structural, optical, electrical properties, and long-term stability of the polymer films. Composite films containing 1, 2, and 4 wt% DNDs were prepared and characterized using structural, optical, and electrical measurements. The incorporation of DNDs resulted in the formation of a modified surface morphology with uniformly distributed nanodiamond-related features and increased optical density over the 350–1100 nm spectral range. Electrical measurements showed that DNDs incorporation increased film resistivity and reduced room-temperature conductivity. However, the activation energy of charge transport in the high-temperature regime decreased from 17 meV for pristine PEDOT:PSS to 9–12 meV for composite films, indicating modified charge transport pathways. The most significant effect of DNDs incorporation was the improvement of long-term electrical stability. After 70 days of storage under ambient conditions, PEDOT:PSS films containing 1–4 wt.% DNDs retained 90–98% of their initial conductance, whereas pristine PEDOT:PSS retained approximately 60% after 50 days. DNDs incorporation provides an effective approach for improving the long-term stability of PEDOT:PSS films.

Organic–inorganic halide perovskite solar cells (PSCs) have become increasingly competitive with traditional photovoltaic technologies, reaching efficiencies of 27

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.

a low-temperature technique for the formation of coatings based on ZnO nanorods decorated with colloidal AgInS2 quantum dots is presented. It is shown that ZnO nanocrystals and colloidal AgInS2 quantum dots with a shell of mercaptopropionic acid molecules form a hetero junction. Sensitization of ZnO nanorods with AgInS2 colloidal quantum dots to visible irradiation provides a gas analytical response of the structure to isopropyl alcohol vapor at room temperature under blue LED illumination with a peak wavelength of 460 nm.

A method for the formation of nanostractured coatings from ZnO nanorods for use in adsorption gas sensors is presented. It has been shown that ultrasonic spray pyrolysis provides the formation of local growth centers for the formation of ZnO nanorods by the low-temperature hydrothermal synthesis. The obtained ZnO nanorods with a small diameter demonstrate a high concentration of oxygen vacancies in the near-surface region of the nanorods and a high surface concentration of hydroxyl groups. An additional method is proposed for testing seed layers by resistance using a liquid probe based on an indium-gallium melt without the need to apply top contacts. The presented technique is suitable for mass production of sensor coatings. The obtained nanostructured coatings from ZnO nanorods demonstrate a high gas analytical response.

Impedimetric biosensors represent a powerful and promising tool for studying and monitoring biological processes associated with proteins and can contribute to the development of new approaches in the diagnosis and treatment of diseases. The basic principles, analytical methods, and applications of hybrid impedimetric biosensors for express protein detection in biological fluids are described. The advantages of this type of biosensors, such as simplicity and speed of operation, sensitivity and selectivity of analysis, cost-effectiveness, and an ability to be integrated into hybrid microfluidic systems, are demonstrated. Current challenges and development prospects in this area are analyzed. They include (a) the selection of materials for electrodes and formation of nanostructures on their surface; (b) the development of efficient methods for biorecognition elements’ deposition on the electrodes’ surface, providing the specificity and sensitivity of biosensing; (c) the reducing of nonspecific binding and interference, which could affect specificity; (d) adapting biosensors to real samples and conditions of operation; (e) expanding the range of detected proteins; and, finally, (f) the development of biosensor integration into large microanalytical system technologies. This review could be useful for researchers working in the field of impedimetric biosensors for protein detection, as well as for those interested in the application of this type of biosensor in biomedical diagnostics.

The application of an additional nanoparticle layer is a common practice for enhancing the optical and electrical properties of third-generation solar cells. In this study, we present the results of impedance spectroscopy (IS) for modified solar cells using Nyquist and Bode diagrams. The structure investigated consists of a conventional double junction based on crystalline silicon (c-Si) coated with thin films of inorganic perovskite nanocrystals (NC) of lead halides CsPbI3 and CsPbBr3. The latter are characterized by a significant phonon disorder, which leads to unique electron-phonon interactions and dielectric responses. The IS results indicate that, under the same conditions, the measured Nyquist plots align well with the simulated ones. An equivalent circuit model is proposed, featuring ohmic resistance, recombination resistance, and geometric capacitance. These elements arise due to charge accumulation, charge transfer resistance, and/or additional interfacial electronic states. The study finds that the introduction of a CsPbI3 layer enhances the photoresponse under bias conditions, but this photoresponse leads to a decrease in DC conductivity. In contrast, the addition of a CsPbBr3 layer obstructs the photoresponse under bias while slightly improving the photoresponse in the absence of an applied voltage. The results obtained contribute to the improvement of tandem solar cell characteristics featuring top layers of perovskite nanocrystals.

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.

Studies on the generation of terahertz (THz) radiation in p-n-heterostructures based on a-Si:H/c-Si upon their photoexcitation by a femtosecond titanium-sapphire laser with a wavelength of 800 nm are presented. The properties of observed THz radiation allow to explain its nature by excitation of fast photocurrent of nonequilibrium charge carriers created in the region of the potential barrier under femtosecond interband photoexcitation of the structure. The fast photocurrent, in turn, emits THz electromagnetic waves. The waveforms and amplitude spectra of the observed THz radiation reflect the dynamics of photoexcited charge carriers in the structures. The intensity of THz radiation observed in the studied p-n-heterostructures based on a-Si:H/c-Si is comparable to that generated in n-InAs crystals, which are widely used as emitters in systems of THz time-domain spectroscopy. Therefore, a-Si:H/c-Si p-n-heterostructures can be used as THz emitters for need of THz spectroscopy. Keywords: femtosecond laser photoexcitation, heterostructures, fast photocurrent, terahertz electromagnetic radiation.

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.

In this study, we conducted an investigation into the Ag/SnSe/Ge 2 Se 3 /W ionic memristor, focusing on the determination of activation energies associated with its two primary operational processes: the formation of conductive filaments and memristor degradation. To ascertain the electrical conductivity of the memristor in both its basic electronic states, a low resistance state and a high resistance state, we constructed current-voltage characteristics. The estimation of activation energy values was carried out employing the Arrhenius law and the provisions of irreversible thermodynamics, with specific reference to Onsager's second postulate. This fundamental concept posits that the growth rate of irreversible component of entropy can be expressed as the summation of products involving fluxes and thermodynamic forces when a system tends towards its equilibrium state. In the context of this study, the equilibrium state of the memristor is defined as the condition at which the memristor can no longer function as a resistive memory cell. Our experimentation involved the application of a flux of Ag + ions (electromigration). The calculated activation energy values were found to be 0.24 eV for the initial process and 1.16 eV for the latter. These divergent activation energy values indicate the differentiation between the agglomerative mechanism that governs the formation of conductive channels, prevalent in the Ag/SnSe/Ge 2 Se 3 /W memristor, and the "conventional" substance transfer mechanism based on a group of point defects that manifests itself during the memristor's degradation.

This communication describes a strategy to synthesize stable deep blue FAPbBr3 quantum dots (QDs) by constructing a matrix structure. Amorphous Ni2+-based metal halide matrices can stabilize QDs from both chemical and physical factors, and Ni2+ doping can further enhance their structural stability due to lattice shrinking. Such deep blue QD films exhibit stable X-ray diffraction patterns and photoluminescence even after 245 days of storage.

The results of studying thin polycrystalline perovskite layers of CH3NH3PbI3 (MAPbI3) are presented. The resulting MAPbI3 layers demonstrate a characteristic absorption spectrum, optical band gap, and photoresponse to irradiation in the visible region of the spectrum. Two crystallization mechanisms have been found in the MAPbI3 layer during heating, which ensure the formation of a film of crystallites with characteristic sizes of 100–200 nm and long dendritic structures with a length of more than 50 μm. A spacecharge-limited current regime has been registered, as well as hysteresis due to ion migration.

Perovskite light-emitting diodes (PeLEDs) have demonstrated rapid development during the past decade, whereas the inferior device performance of blue ones impedes the application in full-color display and lighting. Low-dimensional perovskites turn out to be the most promising blue-emitters owing to their superior stability. In this work, a multidentate zwitterionic l-arginine is proposed to achieve blue emission from pure bromide-based perovskites by in situ-forming low-dimensional nanosheets. First, l-arginine can promote the formation of perovskite nanosheets due to the strong interaction between the peripheral guanidinium cations and [PbBr6]4- octahedral layers, enabling a significant blue-shift. Second, the carboxyl group within l-arginine can passivate uncoordinated Pb2+ ions, improving the device performance. Finally, a blue PeLED is successfully constructed on the basis of the l-arginine-modulated perovskite film, demonstrating a peak luminance of 2152 cd/m2, an external quantum efficiency of 5.4%, and operation lifetime of 13.81 min. Further, the enlightenment from this work is hopefully to be applied in rationally designing spacer cations for low-dimensional perovskite optoelectronic devices.

Coherent terahertz radiation has been generated in p–n heterostructures based on a-Si:H/a-SiC:H/c-Si excited by 800-nm femtosecond laser pulses at room temperature. Terahertz radiation is generated when a reverse bias voltage is applied to heterostructures. The properties of the generated terahertz radiation strongly depend on the bias voltage, which reflects the dynamics of nonequilibrium charge carriers produced by femtosecond laser pump in the heterostructure.

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.

In this study, we conducted an investigation into the Ag/SnSe/Ge2Se3/W ionic memristor, focusing on the determination of activation energies associated with its two primary operational processes: the formation of conductive filaments and memristor degradation. To ascertain the electrical conductivity of the memristor in both its basic electronic states, a low resistance state and a high resistance state, we constructed current-voltage characteristics. The estimation of activation energy values was carried out employing the Arrhenius law and the provisions of irreversible thermodynamics, with specific reference to Onsager's second postulate. This fundamental concept posits that the growth rate of irreversible component of entropy can be expressed as the summation of products involving fluxes and thermodynamic forces when a system tends towards its equilibrium state. In the context of this study, the equilibrium state of the memristor is defined as the condition at which the memristor can no longer function as a resistive memory cell. Our experimentation involved the application of a flux of Ag+ ions (electromigration). The calculated activation energy values were found to be 0.24 eV for the initial process and 1.16 eV for the latter. These divergent activation energy values indicate the differentiation between the agglomerative mechanism that governs the formation of conductive channels, prevalent in the Ag/SnSe/Ge2Se3/W memristor, and the "conventional" substance transfer mechanism based on a group of point defects that manifests itself during the memristor's degradation.

In an Ag/SnSe/Ge 2 Se 3 /W ionic type memristor, the activation energy of two main processes responsible for its operation has been determined, namely: the activation energy for the formation of a conductive channel and the activation energy for memristor degradation. By measuring the current-voltage characteristics, the electrical conductivity of the memristor in low- and high-resistance operating modes was assessed. To determine the activation energy, the Arrhenius law and the provisions of the thermodynamics of irreversible processes were used, in particular the second postulate of Onsager, according to which the growth rate of the irreversible part of the entropy of a system tending to equilibrium is proportional to the sum of the products of the flows occurring in the system and the generalized thermodynamic force corresponding to each flow. The equilibrium state of the memristor was taken to be the state in which the memristor lost the ability to function as a resistive memory cell. The flow of Ag+ ions – electromigration was used as a substance flow. For the first process, the activation energy was 0.24 eV, and for the second, 1.16 eV. The different values of activation energy reflect the difference between the agglomeration mechanism of formation of a current-conducting channel, typical of an Ag/SnSe/Ge 2 Se 3 /W memristor, and the “standard” mechanism of substance transfer based on a group of point defects, which accompanies the process of memristor degradation.