In this study, the series resistance (Rs) was varied between 1 Ω and 6 Ω to analyze its effect on device performance. As shown in the simulation results, increasing leads to a noticeable reduction in FF, Jsc, and PCE, while the impact on Voc is relatively minor. High introduces additional resistive losses, which impede charge carrier transport and increase power dissipation within the cell. The optimal performance was observed at a series resistance of 1 Ω, where the cell achieved a Voc of 0.8489 V, a Jsc of 35.601 mA/cm 2 , an FF of 81.75%, and a PCE of 24.71%. These results align with prior studies indicating that minimizing series resistance is crucial for achieving high efficiency in perovskite solar cells. For instance, efficient contact engineering and the use of highly conductive materials at interfaces have been shown to mitigate resistive losses effectively , .