Modelling and Performance Optimization of Non-Toxic 2-T Perovskite/GeTe Tandem Solar Cell with Improved Efficiency

The search for higher efficiency in photovoltaic technology has led to the development of tandem solar cells, which outperform the results obtained from traditional single-junction cells. This paper investigates the design optimization and performance analysis of a non-toxic Perovskite/GeTe based tandem solar cell to find a device structure with improved efficiency. To achieve this, the effectiveness and efficiency of the proposed tandem solar cell are analyzed by investigating the impact of adding a bottom cell through current matching. It also evaluates various factors of the top cell, such as electron transport layers (ETL), hole transport layers (HTL) and their thicknesses, and defect densities. The proposed tandem structure, with top cell consisting of $\mathbf{F T O} / \mathbf{W S}_{\mathbf{2}} / \mathbf{M a S n I}_{\mathbf{3}} / \mathbf{C u S b S}_{\mathbf{2}}$ and the bottom cell with configuration $\mathrm{ZnO} / \mathrm{In}_{2} \mathrm{~S}_{3} / \mathrm{GeTe}$, has the overall power conversion efficiency (PCE) of 39.5565%, a fill factor (FF) of 84.13%, a short circuit current density of $26.75 \mathrm{mA} / \mathrm{cm}^{2}$, and an overall open circuit voltage of 1.7680 volts, with proper current matching between the two cells. All simulations conducted in this work were performed using SCAPS-1D. By achieving high power conversion efficiency and addressing practical manufacturing challenges, this work contributes to the advancement of photovoltaic technology.