Perovskite solar cells have gained significant attention due to their excellent photovoltaic
 performance and simple manufacturing process. However, the use of lead (Pb) in the widely
 studied CH3NH3PbI3 perovskite material limits its large-scale production due to low
 stability in the air. As a result, researchers have turned to lead-free CH 3 NH 3 SnI 3 perovskite
 as a promising alternative. In this study, we used one-dimensional simulation software to
 investigate the photovoltaic properties of CH 3 NH 3 SnI 3 perovskite solar cells with a
 TiO 2 /CH 3 NH 3 SnI 3 /Cu 2 O structure. By adjusting the thickness of the absorbing layer, doping
 concentration, and density of defects, we were able to improve the performance of the solar
 cells. The obtained results of Jsc= 31,519 mA/cm 2 , Voc = 0,965V, FF = 78,717%, and PCE
 = 23,943% demonstrate the potential of lead-free CH 3 NH 3 SnI 3 as a highly efficient and
 environmentally friendly solar absorber.