Optimizing efficiency in CHTS-based solar cells through controlling tin content of (Zn, Sn)O buffer layer and integration of SnS as back surface field layer: a numerical approach

This study optimizes Cu₂HgSnS₄ (CHTS) solar cells by incorporating a Zn_1 − xSn_xO buffer layer and a SnS back surface field (BSF) layer. A detailed numerical analysis was conducted using Solar Cell Capacitance Simulator (SCAPS) software to enhance photovoltaic efficiency. The photovoltaic performance of CHTS-based solar cell CHTS has been evaluated by varying Sn/(Zn + Sn) ratios in the Zn_1 − xSn_xO layer, and an optimal ratio of x = 0.31 at the CHTS/ Zn_1 − xSn_xO interface is identified, potentially exceeding a 17% efficiency benchmark. Furthermore, strategies to improve open-circuit voltage (V_OC) and overall cell performance are investigated, such as modifying the thickness and carrier concentration of the SnS BSF layer. Simulations reveal a significant boost in efficiency, with SnS/CHTS/ Zn_0.69Sn_0.31O cells reaching an efficiency of 25.81%, surpassing traditional CHTS/CdS cell configurations. Analysis through Capacitance-voltage (C-V) and Mott Schottky plots shows that the optimized cells have low capacitance compared to reference cells, emphasizing the effectiveness of interface and material optimization in enhancing solar cell efficiency. Additionally, impedance spectroscopy analysis highlights the enhanced recombination resistance of the SnS/CHTS/Zn_0.69Sn_0.31O cells compared to traditional CHTS/CdS cells. These results offer valuable insights into improving the performance of CHTS-based solar cells, significantly contributing to developing sustainable energy technologies.