In this study, the performance of organic solar cells (OSCs) utilizing poly(3-hexylthiophene):(6, 6)-phenyl C61 butyric acid methyl ester (P3HT:PCBM) material was investigated. The research employed optical and electrical modeling techniques, using the finite element method (FEM). The study explored the impact of varying the thickness of the active layer, consisting of P3HT: PCBM, as well as the influence of first-order recombination on the performance of organic solar cells (OSCs). The OSCs were constructed using a systematic structure of ITO / PEDOT PSS / P3HT: PCBM (with varying thickness) / Ca / Al. Optical simulations were employed to determine an optimal structure that enhances the absorption of light in the vicinity of the P3HT:PCBM active layer. Additionally, the distribution of electrons and holes within the active layer was investigated in the presence of first-order recombination effects. This increased absorption layer subsequently improved the electrical properties of the devices. The electrical investigation involved analyzing J-V curves under both illuminated and dark conditions. From these curves, key parameters such as short-circuit current density (Jsc), fill factor (FF), open voltage (Voc), and power conversion efficiency (PCE) were extracted. These measurements were performed under 100 mw/cm2 of Air Mass (A.M.) 1.5 Global solar conditions. The results revealed a notably high power conversion efficiency of 3.15 % for an active layer with a thickness of 200 nm.