Compositional texture engineering for highly stable wide-bandgap perovskite solar cells

The development of highly stable and efficient wide-bandgap (WBG) perovskite solar cells (PSCs) based on bromine-iodine (Br–I) mixed-halide perovskite (with Br greater than 20%) is critical to create tandem solar cells. However, issues with Br–I phase segregation under solar cell operational conditions (such as light and heat) limit the device voltage and operational stability. This challenge is often exacerbated by the ready defect formation associated with the rapid crystallization of Br-rich perovskite chemistry with antisolvent processes. We combined the rapid Br crystallization with a gentle gas-quench method to prepare highly textured columnar 1.75–electron volt Br–I mixed WBG perovskite films with reduced defect density. With this approach, we obtained 1.75–electron volt WBG PSCs with greater than 20% power conversion efficiency, approximately 1.33-volt open-circuit voltage (Voc), and excellent operational stability (less than 5% degradation over 1100 hours of operation under 1.2 sun at 65°C). When further integrated with 1.25–electron volt narrow-bandgap PSC, we obtained a 27.1% efficient, all-perovskite, two-terminal tandem device with a high Voc of 2.2 volts. Description Rapid quenching maintains the mix Tandem perovskite solar cells require stable, efficient wide-bandgap perovskites with mixed bromide and iodide anions, but these anions are prone to segregation during crystallization that can then limit the device voltage and operational stability. Jiang et al. determined that a gentle gas-quench method produced a bromine-rich surface layer, and that subsequent columnar growth created films with reduced defect density. Solar cells based on these films maintained 90% of their efficiency at 65°C for more than 2200 hours. All-perovskite tandem cells exhibited 27.1% efficiency resulting from a high open-circuit voltage of 2.2 volts. —PDS Rapid crystallization with gas-quenching maintains bromide-iodide mixing for wide-bandgap perovskite films for tandem cells.