Abstract <p>The photovoltaic parameters of a perovskite solar cell with the ITO/ZnO/CH₃NH₃PbI₃/NiO/Ag heterostructure are calculated and optimized. Perovskite CH₃NH₃PbI₃, which is the most promising material for photovoltaic converters, was used as the solar energy absorber. Zinc oxide ZnO with <i>n</i>-type conductivity, which ensures high mobility of electrons, and nickel oxide NiO, which features high performance stability and optimal electrical characteristics for use as a buffer layer with <i>p</i>-type conductivity, were used as electrodes at the junctions with perovskite. Such buffer layers ensure stable, reliable, and long-term operation of a solar cell. The modeling was carried out by solving the system of Poisson equations and continuity equations for electrons and holes in 1D stationary approximation with taking into account defects in the perovskite volume (10¹³ cm^–3) and at the ZnO/CH₃NH₃PbI₃ (10⁸ cm⁻³) and CH₃NH₃PbI₃/NiO (10¹⁰ cm^–3) junctions. Numerical calculations were carried out using the SCAPS-1D software package, which implements the diffusion-drift model of charge transfer in semiconductors. It has been determined that the perovskite layer thickness has an essential influence on the cell key parameters: open-circuit voltage, short-circuit current density, efficiency, and fill factor of current-voltage characteristic. The maximal efficiency (24.3%) is reached at a perovskite layer thickness of around 1.55 μm. In that case, the open-circuit voltage is 1.15 V, the short-circuit current density is 24.6 mA/cm², and the fill factor is 86.6%. The current-voltage characteristic shows that the current density remains stable to the voltage value of around 0.9 V.</p>