Numerical simulations of ultrathin CdTe solar cells with a ZnxCd1−xS window layer and a Cu2O hole transport layer

CdTe solar cells are investigated using a solar cell capacitance simulator software. First, a conventional fluorine-doped tin oxide (FTO)/i-SnO2/CdS/CdTe structure is simulated using input experimental data to verify the simulation process. To make the cell more economical, the thickness of the CdTe layer is decreased, resulting in a degradation of the device performance. To decrease the minority-carrier recombination loss of the designed structure, a p-type Cu2O layer is exploited at the back contact as a hole transport electron blocking layer (HT–EBL). To address the performance degradation, a ZnS/CdS bilayer is used as the window layer. The interdiffusion of Cd into the ZnS due to annealing treatment and the formation of ZnxCd1−xS compound are also studied. Cell parameters include the thickness, doping concentration, and carrier lifetime are then optimized to enhance the power conversion efficiency (PCE). The proposed FTO/i-SnO2/Zn0.5Cd0.5S/CdTe/Cu2O configuration shows the best PCE of 17.5%, short-circuit current density (Jsc) of 27.8 mA/cm2, open-circuit voltage (Voc) of 0.87 V, and fill factor of 72.34% under AM1.5G illumination.