In this work, a comprehensive numerical study of a perovskite-based solar cell incorporating titanium dioxide as the electron transport layer (ETL) and Spiro-OMeTAD as the hole transport layer (HTL) is presented. The device was simulated under standard 1-sun AM1.5D illumination using COMSOL Multiphysics. A mathematical model was developed to describe the optical generation rate and its direct correlation with the photocurrent density, providing deeper insight into carrier generation and transport mechanisms within the perovskite absorber. The simulated results yield a power conversion efficiency (PCE) of approximately 15% with a fill factor (FF) of 60%. The external quantum efficiency (EQE) was found to be around 60%, indicating efficient photon-to-electron conversion. The simulated performance exhibits strong agreement with previously reported experimental results, confirming the validity of the proposed model. This study establishes a reliable computational framework for the physical understanding and optimization of perovskite solar cells under realistic illumination conditions.