Two-dimensional Dion-Jacobson (DJ) perovskites have shown improved structure stability in comparison with Ruddlesden-Popper (RP) perovskites. However, the mechanism behind the improved stability is still largely unexplored. Here a multifluorinated aromatic spacer, namely, 4F-PhDMA, has been successfully developed for 2D DJ perovskites. It is found that the 2D DJ perovskite with a 4F-PhDMA spacer exhibits a high dissociation energy due to the multiple noncovalent interactions. The optimized 2D DJ device based on the 4F-PhDMA spacer (n = 4) exhibits a champion efficiency of 16.62% with much improved light and thermal stability. This efficiency is much higher than that of the control device using an unfluorinated spacer (n = 4, PCE = 10.11%) and is among the highest efficiencies in aromatic-spacer-based 2D DJ perovskite solar cells (PSCs). Our work highlights the importance of incorporating multiple noncovalent interactions in the 2D DJ perovskite by employing a multifluorinated aromatic spacer to achieve DJ PSCs with both high efficiency and high stability.
Keywords: Dion−Jacobson perovskite; carrier lifetime; solar cells; trap density.