In this work, we developed an I-V curve model of p-type c-Si-based solar cell (SC) with a passivated emitter at the rear contact after irradiation with 1 MeV electrons. The I–V curve is one of the key output characteristics of SCs and solar panels (SPs), from which all the main electrical parameters can be obtained and the performance of the developed design can be evaluated. Radiation is high-energy particles, which, as a rule, cause defects in the crystal lattice, increasing the internal resistance of the SCs design. The resulting defects create energy levels in the forbidden zone of the semiconductor material that act as capture (traps) or recombination centers. An increase in the concentration of traps leads to a decrease in the minority carriers’ diffusion length, which in turn reduces short-circuit current (I_sc) and open-circuit voltage (U_oc), significantly affecting the efficiency and power of the SC. Modeling of the degradation curves was based on the assumption that the value of minority carriers’ diffusion lengths in the base and emitter of the SC are most affected by ionizing radiation, when exposed to electrons with energy of 1 MeV in the fluence range up to 10¹⁵ cm^-2, which is equivalent in magnitude to the radiation operating conditions of a solar panel (SP). The degradation curves of the main electrical parameters of the SC, including U_oc, series (R_series) and shunt resistances (R_shunt), were obtained. On the basis of the calculated degradation curves of I_sc and U_oc, as well as the physical basis of the SCs operation, it is revealed that U_oc changes more significantly, while I_sc practically does not change due to the small degradation of the minority carriers’ diffusion length in the emitter. The analysis of experimentally obtained I–V curves has shown that the degradation of its maximum power point (24.8%) is affected by the decrease of R_shunt and increase of R_series. Approbation of the I–V curve model based on experimental irradiation of Si-based SCs by electrons with the energy of 1 MeV showed an inaccuracy of no more than 5.3%. Thus, when assessing the radiation resistance of SP, partial replacement of full-scale radiation tests of SCs by modeling will allow to speed up and reduce the cost of work.

The features of short-circuit currents in polar cut samples of α-LiIO3 crystals of the hexagonal modification are investigated. Indium and silver are chosen as conductive coatings taking into account their location in the series of electrochemical tension of metals. These coating materials are typical representatives of the electrochemical series of metal tension before (indium) and after (silver) hydrogen. The measurements were carried out using the SKIP hardware and software complex in the temperature range from Troom to 210 °C without applying an external electric field. The samples under study were not preliminarily exposed to any stimulating external effects: neither temperature, nor electrical, nor radiation, etc. Graphs of short-circuit current dependences on temperature were obtained with different materials of conductive coatings and according to different measurement schemes. An optical study of the surface of conductive coatings was carried out before and after heating. The effect of the material of the conductive coatings on the magnitude and direction of short-circuit current flow in the samples was established. In the case of symmetrical conductive coatings, depending on the application of indium or silver, the currents go in different directions. In the case of asymmetrical conductive coatings, depending on the side of silver application, taking into account the polarity of the crystal, the currents have different directions of flow and a magnitude that differs by more than 2 times. The difference in the temperature dependence graphs of heating and cooling, as well as the structural change in the surface of the materials of conductive coatings, may indicate the formation of new phases.

The method of obtaining ohmic contact to In_0.16Ga_0.84As layers is given in this paper. Contact resistance was measured by the transmission line method with radial geometry of contacts. It is shown that the Ni/Au/Ge/Au/Ge/Ni/Au-based contact is ohmic and reaches a minimum specific contact resistance of 6∙10^-5 Ohm∙cm² after annealing at 450 °C for 5 min. in the atmosphere of forming gas. To measure the dependence of the drift velocity on a high electric field, a sample with a specific shape was chosen that prevents the penetration of high field domains into the measurement area. An expression is obtained that allows for accurate calculation of electric field strength and drift velocity, considering the actual geometric sizes of the sample as determined by scanning electron microscopy. It is shown that the obtained expression allows us to obtain the same field dependences of the drift velocity for In_0.16Ga_0.84As samples with different geometrical sizes.

The paper presents calculations of the performance coefficient for thermoelectric modules with segmented branches and cascade coolers in a wide range of temperature differences. The objects of calculation are a single-stage thermoelectric module with two-section branches and a two-stage thermoelectric cooler. The calculation of thermoelectric modules is carried out for the maximum performance coefficient mode. In the case of a single-stage module, the operation of one branch is considered. For a two-stage module, the number of branches in the first and second stages is the same. The length of the branches in sections and stages is the same. The calculation does not take into account the temperature losses at heat transfers and the Joule heat released during switching. The temperature dependences of thermoelectric parameters are not taken into account in analytical expressions, and are taken into account numerically (by the method of successive approximations) when calculating modules. The calculation results showed that a two-stage cooler is always energetically more advantageous than a cooler with two-section branches, and the greater the operating temperature difference of the module, the greater the difference in their maximum coefficients of performance. The advantage of a cascade cooler is due to the fact that each stage operates in the maximum coefficient of performance mode, and for a segmented branch it is impossible to ensure the maximum coefficient of performance of each section. The calculation results are confirmed by the results of measurements of the energy parameters of real thermoelectric modules in two operating modes ΔT = 77 and 55 K. Single-stage and two-stage thermoelectric modules are designed so that their coefficients of performance are maximum in these operating modes. For the mode ΔT = 77 K, the coefficient of performance of the two-stage module exceeds the coefficient of performance of the single-stage module by five times. When the temperature difference decreases to 55 K, the two-stage module remains a more energy-efficient solution. These results are important to consider for the competent design of thermoelectric modules.