Persons

Two-dimensional (2D) Janus-type materials XMoSiN2 (X = S, Se or Te) are characterized by high values of binding energy and strong built-it field allowing the separation of generated electron-hole pairs within a single layer. These 2D materials are promising for photovoltaic applications. In this work, nanotubes of small diameters based on 2D Janus-type materials SMoSiN2, constructed and optimized, are considered in the framework of modeling. Using density functional theory calculations, the band structures and optical absorption spectra of these nanotubes with different chalcogen arrangements have been obtained. For the considered structures, a wide region of absorption of short-wavelength radiation is observed under tube deformation ε = 12.46 %. XMoSiN2 Janus-type nanotubes act as semiconductors, the electronic and optical properties of which can be controlled by tube deformation.

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Recently, in the components of the lithium-ion accumulators (LIA) an anomalously diffusion behavior of ion transport has been discovered. Currently, the microscopic models LIA, consecutively taking into account sub- or superdiffusion and percolation of lithium ions into LIA, are unavailable. The semi-empirical LIA models, using the fractional-order impedances, based on the impedances of fractional order, which are substantiated by the anomalous diffusion of ions in a percolative disordered medium are becoming popular. In the work an assessment of the influence of anomalous diffusion on the impedance spectra within the framework of sub-diffusion generalization of the electrochemical model has been carried out. Using the subdivision equations with the time derivatives of fractional order, the LIA electrochemical model has been modified. Within the framework of this model, using the Fourier transform of fractional differential operators, an equivalent circuit, generalizing popular LIA circuit models has been derived. It has been shown that the slope of a rectilinear low-frequency part of the Nyquist diagram does not always unambiguously determine the subdivision coefficient α and can be both larger and smaller than the slope corresponding to normal diffusion. It has been stipulated that the degradations of the battery properties is associated with a change of the diffusion type in the LIA components.

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The hybrid systems based on the carbon nanotubes (CNT) and fullerenes (nanopipodes) are promising for applications in nanoelectronics. With insignificant variation of the CNT diameter the change of the fullerenes geometry takes place. The periodically located inside fullerenes represent a set of quantum points in the one-dimensional super-lattice. Using the variation of inside fullerenes it is possible to modulate the zone structure of the CNT - fullerene system and to control the electronic and phonon characteristics of nanopipodes. In the work the optical and thermoelectric properties of CNT with encapsulated molecules of C fullerene have been investigated. Using the first-principle methods the coefficients of absorption, optical conductivity, thermal conductivity, thermoelectric figure of merit for CNT with fullerenes, periodically located inside the nanotubes at different distances from each other, have been calculated. It has been shown that with decreasing the distance between fullerenes the optical conductivity of CNT - C is suppressed at high frequencies. It has been determined that the conductance of the structures with fullerenes is less than the conductance of a clean tube, and approximately equal for considered distances (12.3 and 19.7 Å) between fullerenes. The CNT thermal conductivity due to the encapsulation of fullerenes considerably (3-4 times) decreases for the considered CNT (8.8) - C systems.

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The idea of solar cells with a distributed heterojunction consists in spreading the donor-acceptor border on the entire volume of the active layer to improve the efficiency of dissociation of photogenerated excitons. This principle in terms of the model has been generalized for the case of betavoltaic elements that convert the energy of the radioactive beta decay into electricity. The distributed in volume radioisotope source in the form of microparticles has been considered. The efficiency of dissociation and recombination and the recombination probability of generated carriers have been calculated. It has been shown that the dependence of the device efficiency on the scale parameter of the impurity has the maximum, determining the optimal structure of the three-dimensional heterojunction.

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The influence of many factors on the electronic transport in organic semiconductor systems in conditions of the time-spacing experiment has been studied. For estimating the influence on the photo current kinetics of such factors, as the density states, the morphology of the percolation regions, the existence of defect layers , the nonhomogeneity of electric field, etc., the efficient Monte-Carlo algorithm, based on the interpretation of transient current as a density of the generalized random recovery process, has been applied. The test calculations for some multilayer structures have been made.

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