Unlike conventional CIGS solar cells that use CdS as a buffer layer, this study demonstrates a simplified architecture that completely avoids cadmium-based materials while integrating ZnO:Al and CuSCN as efficient, non-toxic charge transport layers. The device under investigation features the structure ITO/ZnO:Al/CIGS/CuSCN/Ag, and its photovoltaic performance is analyzed through SCAPS-1D simulation. We simulated the QE, J-V, and C-V characteristics and showed how variations in absorber and charge layer thickness, as well as defect density, series-shunt resistance influence the short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF), and efficiency (η) of the solar cell. The simulation yielded the following ideal output factors: power conversion efficiency (PCE) of 20.21%, FF of about 84.21%, VOC of 0.84 V, and JSC of 28.54 mA/cm2, respectively.