Effect of Charge-Modulated Molecular Passivator on Methylammonium/Bromine-Free Inverted Perovskite Solar Cells

This study explores the potential of molecular passivation to enhance both the efficiency and operational stability of perovskite solar cells. We investigate the impact of diammonium iodide functional molecules with aryl or alkyl cores on 3D-perovskite surfaces. We found that piperazine dihydriodide, featuring an alkyl core and an electron-rich -NH terminal was effective in mitigating surface and bulk defects. This molecular passivator not only modifies surface chemistry but also improves carrier extraction efficiency, leading to an impressive 23.17% efficiency with superior long-term stability. Detailed device analysis suggests that robust bonding interactions significantly reduce defect densities in the perovskite film and suppress ion migration. This report provides insights into the synergistic effect of bifunctional molecules in defect mitigation, paving the way for design strategies centered on bonding-regulated molecular passivation to enhance both the performance and stability of solar cells.