Path Toward High-Efficiency CZTS Solar Cells with Buffer Layer Optimization
Wafaâ Henni, Wassila Leïla Rahal, D. Rached
Abstract
In this work, we numerically improve the performance of kesterite thin film solar cells (ZnO/Cu2ZnSnS4/CdS/MoS2) using the Solar Cell Capacitance Simulator. The work carried out is mainly based on the study of the influence of the doping density, the thickness, and the gap energy of the buffer layer on the cell's performance. Based on the simulation results, it is found that increasing the buffer layer thickness strongly deteriorates the cell's performance. An optimized and economical CdS buffer layer with a thickness of 15 nm and band gap of 3.2 eV is proposed. It is also shown that it is important to control the doping density of this layer in order to obtain a compromise between the p-n junction electric field and the global recombination rate, to produce efficient solar cells. After optimizing the studied solar cell, promising results are achieved with a conversion efficiency of 17.93%, a fill factor of 71.23%, a short-circuit current density of 30.92 mA/cm 2 , and an open circuit voltage of 0.814 V. The obtained results will provide some important guidelines for producing high-efficiency Cu2ZnSnS4 solar cells.