In this work we present the effect of Si doping on the structural, optical, and photoelectrochemical properties of (CdS)(1-x-y)(ZnS)(x)Si-y coupled films. These films were prepared by the screen printing and sintering technique without the use of CdCl2 or ZnCl2 as flux materials. Two levels of Si doping, 4 and 8% by weight, were attempted. Our data indicate better results for the lower level of Si doping. Electrochemical impedance studies, as well as Mott-Schottky plots, gave a closer insight into the effect of Si on charge transfer and charge buildup in these systems. In general, Si doping has little effect on the resistivity and flatband potentials of (CdS)(x)(ZnS)(1-x) films. However, it induces changes in film microstructure that modified the nature of the traps and surface states associated with recombination and charge-transfer processes, resulting in an enhancement in photocurrent and film stability. These findings are in agreement with the mechanism proposed by other authors.