Simulation of CZTSSe Solar Cells with a Hole Transport Layer of Sb2(S1‐x,Sex)3

In this study, Cu2ZnSn(S,Se)4 (CZTSSe) solar cell with a hole transport layer (HTL) of Sb2(S1‐x,Sex)3 is simulated by Solar Cell Capacitance Simulator (SCAPS). First, the effect of the Sb2(S1‐x,Sex)3 bandgap (Eg) on device performance is analyzed. When Eg is 1.5 eV, the valence band offset (VBO) between CZTSSe and Sb2(S1‐x,Sex)3 is −0.003 eV, forming a nearly flat‐band structure that is favorable for hole transport. Subsequently, several key parameters of the device are optimized. The optimal thickness of the absorber layer is 3.5 µm, and the defect density needs to be controlled below 1013 cm−3. The optimum thickness of the Sb2(S1‐x,Sex)3 layer is 20 nm, and the ideal doping density is 1017 cm−3. The defect densities at the CZTSSe/Sb2(S1‐x,Sex)3 and CZTSSe/CdS interfaces should be controlled at 1014 and 1013 cm−2 or less, respectively. The work function of the back‐electrode should be no less than 5.1 eV. Finally, CZTSSe solar cell can achieve the best efficiency of 22.07%. The simulation results demonstrate the potential to provide a new device structure for fabricating high performance CZTSSe devices.