Perovskite/Silicon Tandem Solar Cells: Choice of Bottom Devices and Recombination Layers

Perovskite/silicon tandem solar cells have been intensively studied in recent years, and their efficiencies have rapidly increased owing to the numerous efforts in this field. A question about which type of silicon solar cell is the most suitable subcell in tandem devices emerges. Herein, three attractive silicon solar cells are summarized, including passivated-emitter rear-cell (PERC), tunnel oxide passivated contact (TOPCon), and heterojunction (HJT) cells. Their structures and features are elucidated for a clear understanding of the mechanism and potential of optimum performance. Moreover, the characteristics and performance of perovskite/silicon tandem cells with PERC, TOPCon, and HJT subcells are contrasted and discussed. The significant contribution of the passivation layer and structure design on both sides to photovoltaic properties of tandem devices is emphasized. Especially, the recombination layer between two subcells is analyzed in depth in terms of material chemistry, light absorption, and charge transport with a review on preparing the optimized structure.