Modulating Surface Wettability and Defect States via Multifunctional Amphiphilic Organic Ionic Salts for Efficient and Stable Inverted Perovskite Solar Cells

Abstract Inverted (p‐i‐n) perovskite solar cells (PerSCs) have the potential to overcome the hygroscopicity limitations of the transport layer compared to the conventional (n‐i‐p) PerSCs. However, the performance and stability of inverted PerSCs are often affected by poor wettability of the hydrophobic hole transport layer and high non‐radiative recombination in the perovskite. To address these issues, an interface modification engineering approach is employed using novel π‐conjugated organic alkali metal ion salts (Phen‐OX) that have coordination functionality. The Phen‐OX materials consist of two components, the hydrophobic ligand skeleton and the hydrophilic alkali metal ionic groups, making them amphiphilic. By selecting the amphiphilic Phen‐OX as the anode modification layer, the wettability of the poly[bis(4‐phenyl) (2,4,6‐trimethylphenyl) amine] upper surface can be altered, and the quality of the perovskite film can be improved. Additionally, the chelatable Phen‐OX molecules can help suppress defects in the perovskite layer, reducing non‐radiative recombination. Furthermore, the presence of Phen‐OX promotes the crystallization of perovskite, leading to enhanced efficiency and stability of PerSCs. Finally, the resulting Phen‐OX‐based PerSCs demonstrate optimal efficiency of 25.50% and significantly improved stability. These findings provide valuable insights for the design of new multifunctional materials for PerSCs.