A Two-Step Solution-Processed Wide-Bandgap Perovskite for Monolithic Silicon-Based Tandem Solar Cells with >27% Efficiency

A two-step solution sequential deposition has been successfully applied to narrow-bandgap (below 1.60 eV) perovskite solar cells (PSCs), while it has not been widely used in wide-bandgap PSCs and monolithic tandem solar cells (TSCs). Here, a lead halide complex is formed by introducing a formamidinium iodide (FAI) and rubidium acetate (RbAc) into the first step. The results show that the lead halide complex alters the crystallization kinetics and promotes a prominent orientation (100) growth of the perovskite film, resulting in an efficiency of 27.64% for monolithic perovskite/silicon TSCs. Additionally, an enlarged-scaled tandem device with an efficiency of 22.81% (active area of 11.879 cm2) is also achieved, which is one of the most efficient devices with an area greater than 10 cm2. This work provides an effective strategy to fabricate perovskite/silicon TSCs with high performance, reproducibility, and large area via the two-step solution method, which will accelerate the industrialization of perovskite/silicon tandem technique.