Comparative Thermal Stability of Perovskite Solar Cells Using DFT and OghmaNano

Abstract Perovskite solar cells have become excellent photovoltaic devices because of their extraordinary optoelectronic properties. However, their practical use is limited by their low thermal stability. This research focuses on the photovoltaic properties and thermal stability of three inorganic perovskite materials: Ba0.75Ca0.25TiO3, Ba2CeBiO6, and Rb2YCuI6. To predict device performance, the density functional theory (DFT) method was first applied to determine the optical and electronic properties of the perovskite structures, which were then used as inputs for the OghmaNano simulator. The study initially considered simple FTO/Perovskite/Au single-activelayercells without transport layers over the temperature range of 300–325 K. The Ba0.75Ca0.25TiO3 material showed the highest thermal stability, with the lowest PCE loss of about 3%, compared with 6% for Ba2CeBiO6 and 7.5% for Rb2YCuI6. Subsequently, FTO/Perovskite/Perovskite/Au bilayer devices were studied using perovskite–perovskite interface engineering over the temperature range of 300–330 K. As the temperature increased, the open-circuit voltage decreased, while the short-circuit current density remained almost constant, resulting in a relatively modest reduction in PCE. Charge carrier generation, charge carrier recombination, charge carrier density, quantum efficiency, and thermal stability were investigated for the bi-active-layer devices FTO/Ba2CeBiO6/Rb2Y CuI6/Au and FTO/Rb2Y CuI6/Ba0.75Ca0.25TiO3/Au, without electron and hole transport layers, respectively. Combining DFT results, interface engineering, and OghmaNano device simulations provides a powerful approach for designing simple, effective, and highly thermally stable perovskite solar cells.