Polymerized Surface Passivation for Stable and Efficient Inverted Perovskite Solar Cells

Surface passivation has played an essential role in the rapid advancement of power conversion efficiency (PCE) in perovskite solar cells (PSCs). However, conventional passivation strategies predominantly rely on small molecules such as ammonium-based ligands, which are prone to deprotonation under light exposure and thermal stress, leading to compromised device stability. Here, we report a polymerizable surface passivation material, vinylphosphonic acid (VPA). The vinyl group enables in situ polymerization, while the phosphate group passivates uncoordinated metallic defects. Both theoretical and experimental results confirmed that the polymerized-VPA (PVPA) forms a more robust and stable passivation layer than conventional organoammonium-based small molecules. Consequently, we achieved a PCE of 26.54% (certified as 26.24%). Benefiting from the more stable polymerized passivation layer, our devices demonstrate remarkable operational durability, retaining over 90% of their initial PCE after 1600 h at maximum power point operation under continuous 1-sun illumination. This approach provides a promising passivation layer strategy to enhance the stability and efficiency of perovskite solar cells.