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In this study, we propose a new method based on genetic algorithms to optimize the performance of intermediate-band solar cells (IBSC). Our approach aims to maximize photovoltaic conversion efficiency by judiciously optimizing the geometric and physical parameters of the IBSC structure., which must be partially filled. This filling ensures the presence of both empty states in the intermediate band (IB) to receive electrons from the valence band (VB), and filled states to provide electrons to the conduction band (CB). Recently, studies have observed the effect of IB occupancy on cell efficiency, and calculated the optimal efficiency for IB devices. The analytical expression for optimal IB filling has been utilized for different scenarios involving IB-CB coupling strength and IB region width. In this work we have studied the influence of the intermediate band energy level, the effects of doping on efficiency, short-circuit current, open-circuit voltage, fill factor, and in order to validate our approach on parasitic effects such as series and shunt resistance.

Purpose. Investigation of the influence of textile materials structure of different raw materials for hospital bedding on the ability to provide sensory comfort and durability. Methodology. Theoretical and experimental investigations are based on the main positions of textile materials science. Sensory comfort and durability of textile fabrics were evaluated by thermal and mechanical properties. The measurement of thermophysical characteristics was carried out on the ALAMBETA instrument, the abrasion resistance was determined on a Pilltester type 14. The strength of textile materials, the tangential resistance, the flexural rigidity and the resistance of dyeing to dry friction were determined by standardized methods. Results. A comparative analysis of the sensory comfort of traditional textile materials for hospital bedding and fabric with bamboo fibers was carried out, which is determined by the mechanospecific sensations of skin receptors on the surface texture of the material, its roughness, stiffness, the feeling of cold or warmness when touching. Their thermophysical properties are determined, the evaluation of the feeling of cold or heat when touched is made according to the indicator "thermal absorption coefficient". By the method of an inclined plane the differences of the texture of dry and moisten studied fabrics was analyzed. The results of the wear resistance indicated that all fabric samples have high abrasion resistance; on part of the test specimens after 1200 cycles appeared nap, on mixed fabric – piles. The values of strength and bending stiffness were determined and the effect of 5 washing cycles on these indices was determined. The resistance of the dye to the action of dry friction of all investigated materials is 5 points. Scientific novelty. The comparative analysis of the values of the coefficients of thermal absorption made it possible to evaluate the feeling of cold or heat when touched, which coincide with the results of the provided organoleptic determinations. It has been experimentally proven that the assortment of cotton and mixed textile fabrics used now for bedding can be supplemented with bamboo fiber materials that provide a high level of sensory comfort and durability. Practical value. A new range of textile materials for bed linen has been proposed, taking into account the requirements of sensory comfort and durability. [ABSTRACT FROM AUTHOR]

Investigation of the optical properties of metal-oxide nanoparticle composites is of vital interest as a result of their extensive use in engineering. The optical characteristics of such a composite differ significantly from those of metal nanoparticles and matrix. In addition, there is a significant difference between the theoretical and experimental results for the magnitude of absorption in the far infrared range. In this work, the optical absorption of the composite “dielectric-two-layer nanoparticle” is analyzed, which is a metal ball coated with a layer of oxide and placed in a dielectric medium. Approximate formulas are obtained for the case of a metallic nanoparticle covered with a thin layer of oxide. The absorption coefficient of the nanocomposite is calculated for Argentum particles of different radii with different thickness of the oxide layer, which are in different matrices. Calculations are made for the case when the effective relaxation time depends on the geometric dimensions of the two-layer nanoparticle. It has been shown that with a decrease of the particle radius there is an increase in the contribution of the surface scattering. It has been shown that a composite with nanoparticles of smaller sizes and with a larger thickness of the oxide layer absorbs electromagnetic radiation better. It has been established that an increase in the dielectric constant of the matrix leads to a decrease in the absorption coefficient, which is due to the weakening of the interaction of the electromagnetic wave with the conduction electrons of the metal core. [ABSTRACT FROM AUTHOR]

The purpose of this article is to present theoretical calculations of the optical spectra of periodic silicon nanostructures dependent on their length. For calculations, the structure with silicon nanowires with a constant diameter and period was simulated. The diameter of the nanowires is 80 nm, and the structure period is 100 nm. The dependence of absorption, reflection and transmission spectra on the length of nanowires (500–5000 nm) was investigated. For theoretical studies, the Maxwell equation was solved by the finite difference method in the time domain (FDTD). This method can be applied precisely to general electromagnetic structures, including free-form particles. The advantage of this method is the simplicity and the capability to obtain results for a wide range of wavelengths in single calculation, as well as the capability to specify the properties of materials at any point of the calculation grid, which allows us to consider anisotropic, dispersive and nonlinear environments. At the same time, the FDTD method can be very resource-intensive, especially when simulating complex structures. This method requires from 10 to 30 points per wavelength, and small wavelengths determine the very high sampling frequency. This leads to cumbersome calculations, especially in three dimensions. To simplify calculations, the problem was carried out in two-dimensional form. It is shown that for these parameters of the structure, the reflection coefficient does not depend on the length of the nanowires, although by 30 % it is smaller than that in the solid silicon plate. The transmission coefficient decreases with the increase in the length of the nanowires, although at all calculated wavelengths it remains higher than that in the silicon wafer. It is shown that in the visible region of the spectrum, the absorption coefficient is significantly higher and with the increase of the length of nanowires, an expansion of absorption spectra is observed, indicating an increase in the absorption range of sunlight. It is shown that the use of silicon nanostructures as solar cells is an important and perspective direction of research. [ABSTRACT FROM AUTHOR]

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Copyright of Nanosistemi, Nanomateriali, Nanotehnologii is the property of G.V. Kurdyumov Institute for Metal Physics, N.A.S.U and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)