Researchers at MIT have developed 23.6%-efficient monolithic perovskite/silicon tandem solar cells with improved stability. The cells combine an infrared-tuned silicon heterojunction bottom cell with a cesium formamidinium lead halide perovskite top cell. This design reduces parasitic absorption and improves environmental stability, allowing the cells to withstand a 1000-hour damp heat test at 85°C and 85% relative humidity. The perovskite layer is protected by a SnO₂/ZTO window layer, which prevents shunts and allows for the sputter deposition of a transparent top electrode. The window layer also acts as a diffusion barrier, enhancing thermal and environmental stability. The tandem cells were fabricated on silicon cells with a planar front surface and a textured rear surface to optimize infrared absorption. The cells achieved an efficiency of 23.6% with no hysteresis and stable maximum power over more than 30 minutes under illumination. The study demonstrates the potential of perovskite/silicon tandem solar cells to achieve industry goals of improving efficiencies to over 30% while maintaining low module costs. The research highlights the importance of minimizing parasitic absorption in the window layers to achieve higher current densities and efficiencies in monolithic tandems. The study also shows that the use of a SnO₂/ZTO window layer enables the fabrication of highly efficient perovskite/silicon tandem solar cells with enhanced thermal and environmental stability. The cells were tested under continuous illumination and showed minimal degradation in performance over 1000 hours. The study also demonstrates the effectiveness of the pulsed-CVD process in depositing a window layer that prevents pinholes and shunt pathways. The results indicate that the perovskite/silicon tandem solar cells have the potential to achieve high efficiencies and long-term stability, making them a promising technology for next-generation solar cells.Researchers at MIT have developed 23.6%-efficient monolithic perovskite/silicon tandem solar cells with improved stability. The cells combine an infrared-tuned silicon heterojunction bottom cell with a cesium formamidinium lead halide perovskite top cell. This design reduces parasitic absorption and improves environmental stability, allowing the cells to withstand a 1000-hour damp heat test at 85°C and 85% relative humidity. The perovskite layer is protected by a SnO₂/ZTO window layer, which prevents shunts and allows for the sputter deposition of a transparent top electrode. The window layer also acts as a diffusion barrier, enhancing thermal and environmental stability. The tandem cells were fabricated on silicon cells with a planar front surface and a textured rear surface to optimize infrared absorption. The cells achieved an efficiency of 23.6% with no hysteresis and stable maximum power over more than 30 minutes under illumination. The study demonstrates the potential of perovskite/silicon tandem solar cells to achieve industry goals of improving efficiencies to over 30% while maintaining low module costs. The research highlights the importance of minimizing parasitic absorption in the window layers to achieve higher current densities and efficiencies in monolithic tandems. The study also shows that the use of a SnO₂/ZTO window layer enables the fabrication of highly efficient perovskite/silicon tandem solar cells with enhanced thermal and environmental stability. The cells were tested under continuous illumination and showed minimal degradation in performance over 1000 hours. The study also demonstrates the effectiveness of the pulsed-CVD process in depositing a window layer that prevents pinholes and shunt pathways. The results indicate that the perovskite/silicon tandem solar cells have the potential to achieve high efficiencies and long-term stability, making them a promising technology for next-generation solar cells.