Enhancing Efficiency of CdS/CdTe Solar Cells with Double BSF Layer by Numerical Analysis

Cadmium telluride (CdTe) has emerged as a leading material for solar energy applications due to its high efficiency and affordability. This work primarily focused on optimizing the structure of CdTe-based solar cells to enhance their performance. The Solar Cell Capacitance Simulator (SCAPS-1D) was used to model and evaluate the performance of these solar cells. In this study, a CdTe cell without a back surface field (BSF) was used as the baseline model. The research showed that the standard CdTe cell with a 4000 nm thick absorber layer achieved an efficiency of $\mathbf{1 6. 4 1 \%}\left(\mathbf{J s c}=24.72 \mathrm{~mA} / \mathrm{cm}^{2}, \mathrm{FF}=\mathbf{7 6. 2 1 \%}\right.$, Voc = 0.87 V) without a BSF layer. A modified CdS/CdTe solar cell was then developed by introducing a 100 nm AZO buffer layer, reducing the CdTe absorber layer to $1 \mu \mathrm{~m}$, and adding a GeTe layer over MoTe2 as a BSF. The effect of incorporating a double BSF in the base cell was analyzed using the band diagram. The modified cell demonstrated a significantly higher efficiency of $\mathbf{2 8. 7 4 \%}$, with Jsc $=\mathbf{2 4. 9 4} \mathbf{~ m A} / \mathbf{c m}^{2}$, Voc $=\mathbf{1. 2 7} \mathrm{V}$, and FF $=\mathbf{9 0. 2 0 \%}$. The proposed cell showed enhanced stability at elevated working temperatures, with a low temperature coefficient of $\mathbf{- 0. 1 1 6 \%} /{ }^{\circ} \mathbf{C}$ for the $\mathrm{GeTe} / \mathrm{MoTe}_{2}$ double BSF layer. These findings highlight the potential for further research into using thinner CdTe absorber layers and $\mathrm{GeTe} / \mathrm{MoTe}_{2}$ BSF layers to boost efficiency in CdTe solar cell architectures.