Design and Optical Studies for Nanostructure Intermediate Reflector based Perovskite Silicon Tandem solar cell

In Perovskite-silicon tandem (PST) solar cells, the final current density of cell is decided by the smallest current generated by the perovskite sub cells, as the two cells are in series. Commonly, processing defects occur in thick perovskite layers, which limits the thickness of top perovskite layer. Due to the limited thickness of top perovskite cell (PerC), the cell cannot absorb the photons as it could be, limits the final current density of PST cell. To increase the top cell current, this paper presents the design and discusses the role of nanostructured intermediate reflector (IR). The bottom C-Si cell is optimized to match with the top cell current density. The numerical analysis of the proposed design shows that there is only slight increase in the top cell current density with the presented nanostructured IR. The theoretical analysis is done to understand, the reason behind getting only a slight increase in top cell absorption with patterned IR using effective medium theory. It has been observed that the low index contrast of the materials involved in the IR design are the main reason for low absorption enhancement. The methods that can be used as an alternate to the proposed design to further improve the top cell current density are also discussed.