Numerical Simulations on CZTSSe-Based Solar Cells with GaSe as an Alternative Buffer Layer Using SCAPS-1D

In recent years, because of non-toxic characteristic, relatively high efficiency, and adjustable band gap, the research on thin film solar cells using Cu2ZnSn (SxSe1-x)(4) (CZTSSe) as the absorber layer material has been in full swing. But its large band gap width makes it easy to form an excessive potential barrier with other materials, which leads to the raise of the recombination probability of carriers. Therefore, it is necessary to select a suitable buffer layer to optimize such solar cells. Compared with the common buffer material CdS, GaSe crystal has a high damage threshold, strong anisotropy, and nonlinear optical properties. In this paper, a safe and efficient material, GaSe, was selected as the buffer layer of the solar cell with CZTSSe as the absorber layer. At the same time, traditional holes transport layer was removed to save its complex manufacturing process. The addition of GaSe also adjusted the energy band arrangement of the battery, which alleviated the strong potential barrier between the absorber layer and the window layer to improve the carrier transport effectively. The effects of the impurity ratio, thickness, temperature, and defect density on the device performance were also discussed in detail, which provides a reference for experimental preparation and industrial application.