CHANGES IN THERMALLY STIMULATED CONDUCTIVITY OF CsPbBr3 AND CsPbCl3 CRYSTALS EXPOSED TO X-RAY IRRADIATION

Introduction. CsPbBr3 and CsPbCl3 crystals remain among the most intensively studied materials. This is due to their high efficiency in solar cells, which currently exceeds 22%. However, an unsolved problem is the degradation of these perovskites under the influence of external factors. Materials and Methods. This study investigates monocrystals of perovskites CsPbBr3 and CsPbCl3 subjected to X-ray irradiation. The experiment aims to establish the dose-dependent patterns of changes in the electrical characteristics of the crystals. Research under these conditions is relevant due to the high photosensitivity of the materials in the UV, X-ray, and γ-ray spectra, making them promising for the fabrication of photodetectors in the detection of ionizing radiation. Results and Discussion. It has been found that changes in the activation energies of electrical conductivity may result from alterations in the conduction mechanism due to the formation of perovskite phase transitions in CsPbBr3 crystals. A decrease in activation energies of conductivity in the high-temperature range (160–180 °C) was observed, attributed to the effect of X-rays. A trend towards decreasing activation energies of conductivity with increasing dose of irradiation was identified. In the low-temperature range (30–90 °C), CsPbBr3 crystals exhibited sharp changes in current through the samples, significantly decreasing in the range of (95–140) °C, followed by an increase in current at higher temperatures. It is suggested that these results may be attributed to radiation-stimulated generation of vacancy-type defects (VBr) in CsPbBr3 crystals. The formation of similar phase structures in CsPbCl3 crystals occurs at significantly lower temperatures and much lower corresponding thermoelectric currents, necessitating further detailed investigations for their analysis. The generation of radiation defects in CsPbCl3 crystals becomes significant at doses ≥ 130 Gy. Conclusions. The study establishes that the influence of X-ray irradiation and the subsequent passage of current through CsPbBr3 crystals is accompanied by the formation of two perovskite phases, CsPb2Br5 and Cs4PbBr6. The formation of the corresponding phase structures in CsPbCl3 crystals occurs at much lower temperatures and much smaller values of the corresponding thermal currents, therefore, additional, more detailed studies are required for their analysis.