This work investigate the effect of shell thickness on the photocurrent density in polymer-based solar cells using gold-silver and silver-gold metal-metal core-shell nanoparticles. Simulation results indicate that as the shell thickness increases, the photocurrent density generally rises, and after reaching an optimal point, it stabilizes or slightly decreases. This performance improvement is attributed to enhanced plasmonic effects in the metal-metal combination, which leads to better light trapping and absorption. For instance, for a cell thickness of 80 nm, photocurrent densities of 13.74 mA/cm², 16.62 mA/cm², and 19.3 mA/cm² were obtained for the cell without nanoparticles, with Ag nanoparticles, and with Au-Ag nanoparticles, respectively. These findings highlight the importance of optimizing shell thickness and material composition in core-shell nanoparticles to maximize the efficiency of solar cells.