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

Ligands-assisted interface engineering has been considered as a promising strategy to improve the performance and stability of the perovskite solar cells(PSCs) simultaneously. However, suffered from the insulating property of conventional non-conjugated ligands, trap passivation is always at the expense of sacrificing interface/bulk carrier transporting 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 characteristic of perovskite films via “interfacial stitching effect”. This typical ligand could effectively contribute to the suppression of surface defects and ion mitigation. Furthermore, improved charge transport behavior of perovskite film can be achieved due to the conjugated and delocalization characteristic 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 condition and operation condition without encapsulation.