Perovskite solar cells have attracted significant attention within the scientific community due to their rapidly advancing performance. In particular, inorganic perovskite devices are renowned for their remarkable performance and enduring stability.This study introduces a device optimization process guided by modeling to fabricate high-efficiency perovskite solar cells using lead-free methyl ammonium tin iodide (MASnI3) materials. The studied device follows the general architecture: glass/FTO/WS2/ FASnI3/Cu2o/Au. For these simulations, we employed the SCAPS-1D cell ca-pacity simulator. In addition to temperature, the thickness of different layers and doping concen-tration significantly affects the device’s efficiency. We varied the temperature in the range of 300 K to 400 K. Furthermore, we adjusted the thickness of the HTL layer (from 1 to 3 µm), the absorber layer (from 0.2 to 2 µm), and the ETL layer (from 0.01 to 0.1 µm). Regarding doping concentration, we explored levels ranging from 1013 cm−3 to 1018 cm−3 for the HTL layer, from 1014 cm−3 to 1018 cm−3 for the absorber layer, and from 1015 cm−3 to 1018 cm−3 for the ETl layer. Moreover, the MASnI3-based device showed the highest power conversion efficiency ((PCE) = 20%, fill factor (FF) = 65.03%, short-circuit current density (Jsc) = 27.67 mA/cm2, and open-circuit voltage (Voc) = 1.07 V. The previously reported results were given for 1014 cm−3, 0.1 µm, and 380 K. The findings of this study suggest (MASnI3-based absorber materials can play an important role in high efficiency perovskite solar cells with excellent stability.