26.7% Efficient 4-Terminal Perovskite–Silicon Tandem Solar Cell Composed of a High-Performance Semitransparent Perovskite Cell and a Doped Poly-Si/SiOx Passivating Contact Silicon Cell

The rapid rise in single-junction perovskite solar cell (PSC) efficiencies, tunable bandgap, and low-cost solution processability make PSCs an attractive candidate for tandems with Si bottom cells. However, the challenge is to fabricate a high-performance semitransparent perovskite top cell in combination with an appropriate silicon bottom cell with high response to long wavelength photons that are filtered through the perovskite top cell. Currently, semitransparent perovskite cells show much lower performance compared with their opaque counterparts, while high-performance silicon bottom cells, such as heterojunction with intrinsic thin layer and interdigitated back contact, may be too expensive to meet the cost and efficiency targets for commercial viability. Here, we demonstrate a 26.7% perovskite-Si four terminal (4T) tandem cell comprising a highly efficient 17.8% CsFAMAPbIBr semitransparent, 1.63-eV bandgap perovskite top cell, and a ≥22% efficiency n-type Si bottom cell fabricated with a conventional boron diffused emitter on the front and carrier selective n ⁺ poly-Si/SiO _x passivated contact on the rear. This is among the highest efficiency perovskite/Si 4T tandems published to date and represents the first report of the use of the high temperature-resistant single side n-tunnel oxide passivated contact Si cell in a 4T configuration.