A Comparative Study of Alkylammonium Halide Interface Modification for High Efficiency and Ion Migration Stability Perovskite Solar Cells

Constructing 2D/3D perovskite heterostructures with organic molecules is key to improving the power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). However, a comprehensive understanding of the inhibitory relationship between the 2D perovskite layer and ion migration at the interface is still lacking. In this study, we use different alkyl ammonium iodides to build 2D/3D perovskite heterostructures. The research results show that both the chain length of alkyl and amino group count in alkyl ammonium iodide can significantly affect the crystal structure orientation of the 2D perovskite layer. A Dion-Jacobson (DJ) 2D/3D structure treated with ODADI shows superior defect passivation and carrier extraction, leading to PSCs with a 24.51 % PCE. Furthermore, the perovskite based on ODA cations eliminates the influence of Van der Waals interaction in perovskite based on BA or OA cations, which improves the stability of the lattice structure, and significantly inhibits ion migration. Therefore, after a maximum power point stability test of 1500 h, devices retain approximately 88 % of their initial PCE. This work offers fresh insights into optimizing interfaces in 2D/3D PSCs by selecting suitable organic molecules.