Bulk and surface cooperative passivation enables efficient and stable wide-bandgap perovskite solar cells

Inverted wide-bandgap perovskite solar cells (PSCs) have drawn significant attention due to their excellent optoelectronic properties, low-cost fabrication processes, and good compatibility with tandem devices. However, the presence of bulk and surface defects limits further improvement in their performance. In this work, a synergistic dual passivation strategy is proposed, using 4-hydroxyphenethylammonium iodide (OH-PEAI) as a bulk additive and 4-trifluoromethylphenethylammonium iodide (CF₃-PEAI) as a surface passivation agent. This dual passivation strategy significantly enhances the performance and stability of 1.75 eV perovskite devices by improving crystallization, optimizing energy levels, and passivating defects, achieving a power conversion efficiency (PCE) of 20.22%.