Optimization of two terminal tandem Perovskite/Si solar cells with theoretical modeling

In this paper, an experiment involving two-terminal (2 T) tandem perovskite/Si solar cells was used as the validation case for the simulation. Subsequently, we analyzed the hole transport layer (HTL) in the perovskite (PSK) solar cell, which served as the top cell. The results demonstrate that increasing the bandgap leads to a drop in the open-circuit voltage (Voc), while the fill factor (FF) and efficiency increase, and the short-circuit current density (Jsc) remains constant. The valence band offset for the higher bandgap creates a spike against barriers, causing the Voc to decrease. However, during recombination, the interface recombination is reduced, resulting in enhanced FF and efficiency. The electron affinity of the HTL also significantly impacts efficiency. A range of 2.3–2.6 eV is suitable for highly efficient PSK/Si tandem solar cells. Lower electron affinity values create a cliff that facilitates carrier transport through the PSK layer, reduces recombination rates, and leads to higher efficiency. Materials with higher electron mobility and acceptor density are ideal for selecting HTL materials. Finally, we identified an optimal HTL configuration that enables a tandem device to achieve 2% higher efficiency compared to the reference case. This study highlights the importance of HTL materials in tandem devices.