A lower defect density in the absorber layer is with longer carrier lifetimes and enhanced diffusion lengths, which directly translate to improved device performance. In this study, the defect density of the absorber layer was optimized at 4.5 × 10¹⁴ cm⁻³, yielding a maximum power conversion efficiency (PCE) of 29.45%. This value was selected as the optimal defect density since it resulted in the highest efficiency observed in our simulations. Increasing the defect density beyond this threshold negatively impacts the charge transport and extraction processes, leading to severe non-radiative recombination losses, as reported in previous studies , . The impact of defect density on perovskite materials has been extensively studied. According to Gong et al. , the presence of defects within the perovskite structure introduces trap states that facilitate carrier recombination, thereby reducing the carrier lifetime and diffusion length.