STABILITY STUDY OF THE FUNCTIONAL LAYER IN A PEROVSKITE SOLAR CELL

Abstract

Introduction. One of the types of green renewable energy sources is solar energy, which is considered environmentally friendly. Solar energy is a vast field with many directions, among which perovskite photovoltaics is considered one of the most promising areas. Despite the fact that the efficiency of solar energy conversion has already reached more than 25%, there are a number of obstacles in the use of perovskite solar cells, one of which is low resistance to external degradation factors. The purpose of this work was to study the degradation of the surface of a thin film of perovskite CH₃NH₃PbI_3-xCl_x under the influence of external influences, such as atmospheric moisture and light. A complete understanding of the influence of external factors in the manufacture of each functional layer is considered the most important to ensure the stability of a perovskite solar cell. Method. To study the surface of CH₃NH₃PbI_3-xCl_x, a Quanta 200 3d scanning electron microscope, FTIR spectroscopy of the FSM 2203 type, raman spectroscopy using a Solver Spectrum 600/600 spectrometer and QEX-10 optical absorption were used. With the help of spectroscopy, it was possible to observe the degradation and concomitant evolution of the molecular structure inside the perovskite layer. Results. The study showed that the degradation of the functional layer of perovskite proceeds differently depending on the active factor present in the surrounding atmosphere and during the degradation of the crystal structure of perovskite, new chemical bonds are formed. After exposure to the atmosphere and light, the qualitative characteristics of the optical parameters of the photoconverter deteriorate, which leads to the destruction of the functional layer of perovskite due to hydration degradation and the deprotonation mechanism. The degradation mechanism can be initiated by the breaking of iodide bonds. Strong changes in the absorption intensity of characteristic frequencies corresponding to the functional groups NH and CH at frequencies 3132 1/cm and 3179 1/cm were revealed. Discussion. This paper presents an approach to the study of the structural stability of a separate functional layer of perovskite in order to develop alternative concepts for the manufacture of stable and stable perovskite solar cells.