Chloride-Based Additive Engineering for Efficient and Stable Wide-Bandgap Perovskite Solar Cells

Metal halide perovskite-based tandem solar cells hold the potential for achieving power conversion efficiency beyond the theoretical limits of single-junction cells. Overcoming the open-circuit voltage deficit in wide-bandgap perovskite solar cells is crucial to realizing efficient and stable perovskite tandem cells. This study reports on a comprehensive approach to improving 1.8 eV perovskite solar cells by engineering the perovskite crystallization pathway using chloride additives. When combined with a self-assembled monolayer as the hole-transport layer, an open-circuit voltage of 1.25 V and a power conversion efficiency of 17.0% are achieved. The study highlights the role of methylammonium chloride in guiding the formation of a chloride-rich intermediate phase, facilitating the crystallization of the desired cubic perovskite phase, and inducing more effective halide homogenization, which suppresses halide segregation and improves optoelectronic properties.