Bifunctional π-conjugated ligand assisted stable and efficient perovskite solar cell fabrication via interfacial stitching

Ligand-assisted interface engineering has been considered as a promising strategy to improve the performance and stability of perovskite solar cells (PSCs) simultaneously. Due to the insulating properties of conventional non-conjugated ligands, trap passivation is always at the expense of the interface/bulk carrier transport of the perovskite film. To overcome this paradox, a functional organic amine salt, 3-phenyl-2-propen-1-amine iodide, (PPEAI), is introduced to modify the interfacial characteristics of perovskite films via an "interfacial stitching effect". This typical ligand could effectively contribute to the suppression of surface defects and ion migration. Furthermore, improved charge transport behavior of perovskite films can be achieved due to the conjugation and delocalization characteristics of PPEAI. By employing the optimized PPEAI modified perovskite film, a 21.01% efficiency was obtained from the champion device, with good stability under both ambient conditions and operation conditions without encapsulation.