CCTS-based solar cells show promising performance in the realm of sunlight-based energy production in this study. Optimizing the buffer layer remains a barrier to improving the efficacy of CCTS-based solar cells. The initial structure is made up of a CCTS absorber layer, a ZnO resistive layer, an AZO transport conducting layer, and a window layer, as well as different buffer layers (CdS, ZnS, and ZnSe) to find the best buffer layer. The second structure is made up of a CCTS absorber layer, a ZnO resistive layer, an AZO transport conductive layer, a window layer, and different buffer layers (CdS, ZnS, and ZnSe) to find the best buffer layer. The second structure consists of the same layers as the first structure, minus the resistive layer ZnO, while the third structure consists of the same layers, minus the window layer AZO. The solar cell in this structure's open circuit (Voc), short circuit current (Jsc), fill factor (FF), and conversion efficiency (PCE) revealed that the first structure has good agreement, and that these buffer layers were used to investigate the effect of buffer thickness as alternative buffer layers. Among these three buffers, cadmium sulphide CdS) is preferable over Zns and ZnSe, and after improving the initial structure, the power conversion efficiency (PCE) was 13.47% for buffer Cds, 13.46%. The simulation showed that for structure MO / CCTS /(CdS)/ZnO / AZO at (3100) nm of absorber layer (CCTS), 40 nm of buffer layer (cds), 10 nm of resistive layer (ZnO), and 60 nm of AZO performs the best for (Voc = 0.573 V, Jsc = 30.344 mAcm-2, FF = 72.57 %, and PCE = 13.91%).