Surface post-treatment using organic spacer cations is one of the effective methods to suppress defects and reconstruct the microstructure of perovskite films. However, larger organic spacer cations can transform the perovskite surface structure into an uncontrollable low-dimensional phase, significantly limiting charge transport at the interface within perovskite solar cells ( PSCs ).
Liu Mingzhen and others from the University of Electronic Science and Technology of China designed a bimolecular competitive adsorption strategy using phenylmethylammonium iodide ( PMAI ) and octylamine iodide ( OAI ) as co-modifiers from the perspective of molecular dynamics. OA + is preferentially adsorbed on the surface of the perovskite film due to its larger molecular polarity and steric hindrance effect, thereby inhibiting the PMA + -induced transformation of the surface layer into a low-dimensional structural phase. Therefore, this strategy eliminates the limitations of interfacial charge separation and extraction on perovskites and enables devices with PCE as high as 25.23% .
This bimolecular dynamics competitive strategy was also applied to flexible PSC devices, which achieved a PCE of 23.52% . After 1,000 hours of maximum power point tracking ( MPPT ) under continuous illumination , the unencapsulated cells functionalized with bimolecular ligands maintained 88% of their initial performance, demonstrating excellent operational stability.
Yinyi Ma et.al Bi-molecular Kinetic Competition for Surface Passivation in High-Performance Perovskite Solar Cells EES 2024
DOI: 10.1039/D3EE03439A