Dual-Absorber Solar Cell Design and Simulation Based on Sb₂Se₃ and CZTGSe for High-Efficiency Solar Cells

Inorganic solar cells based on the binary-type metal chalcogenide semiconductor, particularly Sb₂Se₃, have recently garnered significant interest due to their abundant and nontoxic natural elements, strong thermal stability, and favorable optoelectronic properties. Single-absorber solar cells using antimony selenide have been the most common choice to date but have shown only limited efficiency in converting sunlight into electricity. The primary aim of this research is to examine a device structure that demonstrates an enhanced efficiency. The study explores the potential of utilizing CZTGSe as a secondary absorber layer to enhance photovoltaic performance metrics. The basic solar cell structure studied is FTO/CdS/Sb₂Se₃/Cu₂O/Au, which has a power conversion efficiency of 24.94%. By conducting simulations using SCAPS-1D, an in-depth analysis of the proposed dual-absorber structure (FTO/WS₂/Sb₂Se₃/CZT_0.2G_0.8Se/Cu₂O/Au) was carried out. Solar cell efficiency was enhanced through the adjustment of the Ge concentration in the secondary CZTGSe absorber with various electron transport layers (CdS, ZnSe, WS₂, and ZnOS). The findings indicate that optimal efficiency is achieved at a Ge concentration x = 0.8, with WS₂ emerging as the most effective among the proposed ETLs. The physical characteristics of the layers, including their thickness, doping density, and impurity level, as well as the interfaces, were then modified to improve device performance. The photovoltaic device achieves a fill factor of 88.31%, a V_OC of 1.117 V, a J_SC of 38.23 mA/cm², and an efficiency of 37.76% when all factors are perfectly optimized. This study proposes that CZTGSe has the potential to be utilized in creating a stable, cost-efficient Sb₂Se₃ solar device with high efficiency.