Investigation of Photoelectric Converters with a Base Cadmium Telluride Layer with a Decrease in Its Thickness for Tandem and Two-sided Sensitive Instrument Structures

Photovoltaic cells with a base layer of cadmium telluride with a decrease in its thickness are studied. It is known that the widespread use of photovoltaic converters is constrained by their high price in the case of highly efficient instrument structures, or low efficiency. The creation of tandem and two-sided sensitive photoelectric converters will reduce their cost while increasing their efficiency. However, to create tandem and two-sided sensitive photoelectric converters, the necessary conditions are the use of transparent contacts and a decrease in the thickness of the base layer for efficient absorption of incident radiation by the converter, which is lower. In the research process, it was found that reducing the thickness of the base layer to 1 μm allows to increase the efficiency of the photoelectric transducer during irradiation from the back. An increase in the efficiency of the photoelectric converter occurs due to a decrease in the distance from the generation region of nonequilibrium charge carriers in the region of separation. If the thickness of the base layer is less than 1 μm, then regardless of which side of the irradiation is carried out, a decrease in the efficiency of the instrument structure is observed. Increase in the efficiency of photoconverters is associated with an increase in the negative influence of recombination processes on the back contact, a decrease in the number of charge carriers generated due to incomplete absorption of incident radiation, and a decrease in the volume of the built-in field of the separating barrier when it overlaps with the depletion region of the back contact. ITO/CdS/CdTe/Cu/ITO SCs with a base layer thickness of 1 μm demonstrates degradation stability. The highest value of efficiency in the case of illumination from the front side 8.1 % and with illumination from the back side 3.8 % received after a year of operation of the photovoltaic converter

Investigating an Alternative Electricity Supply System for Preventing Emergencies Under Conditions of Limited Capacity

Film solar cells have been investigated to meet the need for an alternative system of electricity supply during the elimination and prevention of an emergency when an electricity supply system is damaged. Given the high degradation resistance of cadmium telluride, the study has examined the two-way sensitive solar cells based on CdS/CdTe with a super-thin base layer suitable for forming tandem structures. Creating the tandem structures makes it possible to improve the efficiency by placing another photoconverter at the front surface. We have measured the light volt-ampere characteristics of ITO/CdS/CdTe/Cu/ITO solar cells with a base layer thickness of 1 µm when simultaneously lighting the rear and frontal sides. It has been experimentally shown that two-way lighting makes it possible to increase the electrical power generated by the device structure by 30 %.The study of the spectral dependences of transmittance has shown that the device structures ITO/CdS/CdTe/Cu/ITO with a thickness of the base layer of 1 µm demonstrate, in the spectral range (0.82‒1.10) µm, average transmittance of 0.58. Examining the light volt-ampere characteristics of the solar cells Mo/CuInSe2/CdS/ZnO/ZnO:Al/Ni: Al/Ni has shown that placing, at its frontal surface, the solar element ITO/CdS/CdTe/Cu/ITO leads to a decrease in efficiency from 11.2 % to 6.0 %. Such a decrease is primarily due to a decrease in the short-circuit current density from 25.9 mA/cm2 to 13.8 mA/cm2. However, as the efficiency of the ITO/CdS/CdTe/Cu/ITO solar element is 7.8 %, the tested tandem photovoltaic converters ITO/CdS/CdTe/Cu/ITO – Mo/CuInSe2/CdS/ZnO/ZnO:Al/Ni demonstrated the efficiency 13.8

Building A Model and an Algorithm for Modeling the Movement of People Carrying Goods When They Are Evacuated From Premises

Evacuation is often the only way to save a person who is in a life-threatening situation. At present, evacuation software is used to simulate the movement of human flows, which does not always reflect the real processes of their movement. Therefore, it is a relevant task to build models for modeling the movement of human flows for different types of emergencies, different categories of human movement, and various spatial forms of their representation. Such a task arises when evacuating people from premises for various functional purposes. During evacuation, people often carry some goods. When people move carrying some goods, their horizontal projection takes a more complex shape than an ellipse or circle considered in earlier studies. Moreover, in practice, there is often a task to model the movement of people taking into consideration the maximum permissible distances between them. This paper reports the new quasi-phi functions of interaction between the ellipse and rectangle accounting for the maximum allowable distances between them. The proposed mathematical apparatus has made it possible to formalize the interaction between objects, thereby enabling the construction of a well-substantiated mathematical model, as well as the methods and algorithms for modeling the movement of people carrying some goods. The possibility to simulate the movement of people with certain objects has shown taking into consideration the maximum permissible distances between them. A test example of the movement of people along four corridors was simulated, in each of which there were 28 people subsequently merging into one flow. Given the uniform distribution of three types of cargo: «backpacks», «suitcases», and «bags on wheels», the movement slowed down by about 4 %. When half of the evacuees had «bags on wheels» that can move away from people at arm's length, the slowdown was about 6 %

Devising A Procedure to Forecast the Level of Chemical Damage to the Atmosphere During Active Deposition of Dangerous Gases

This paper reports a procedure devised to forecast the level of chemical pollution of the atmosphere, which includes a mathematical model for the distribution of the concentration of dangerous gas in the atmosphere at its active deposition by dispersed jets of liquid, as well as a technique for its implementation. Based on the differential equations of gas distribution in space, a phased model of the propagation of a cloud of a dangerous chemical substance was built. The model describes stages in the discharge of a dangerous gaseous substance from emergency technological equipment, the deposition of dangerous gas by a finely-dispersed flow, and free propagation of the cloud in the air. The reported mathematical model makes it possible to calculate the size of pollution zones while determining the boundary safety conditions. When forecasting, the main meteorological parameters, the width of the deposition zone, and the chemical properties of both the gas and liquid are taken into consideration. The comparative analysis of the results of forecasting a conditional zone of chemical damage with the free propagation of the cloud, and at the active deposition by precipitation or technical devices, was carried out. The simulation results revealed that with an increase in the wind speed from 1 m/s to 5 m/s, the size of the affected area increases by 2.7 times, while the concentration of dangerous gas in the cloud falls by 2.5‒3 times. An algorithm has been proposed for integrating the devised methodology of forecasting the level of chemical pollution of the atmosphere into a general cycle of emergency management. It should be especially noted that the devised procedure contains the entire range of components that are necessary for its practical application. It includes a description of the procedure and practical recommendations for the use of the proposed technique in the elimination of emergencies, as well as a list of probable events when the use of the developed procedure would be most effective