Optical and Compositional Engineering of Wide Band Gap Perovskites with Improved Stability to Photoinduced Phase Segregation for Efficient Monolithic Perovskite/Silicon Tandem Solar Cells

Metal halide perovskites are promising candidates for the wide band gap top cell in tandem solar cells. By introducing a tin oxide buffer layer via atomic layer deposition, we have improved the efficiency of monolithic, two-terminal, perovskite/silicon tandems to 23.6% by combining an infraredtuned silicon heterojunction bottom cell with the more stable cesium formamidinium lead halide perovskite. We show that further improvements to current and voltage can be made by introducing a PDMS scattering layer to reduce front surface reflection and using compositional engineering to simultaneously increase bandgap and V oc , while mitigating voltage losses arising from photo-induced halide segregation.