Multilayered Perovskite Materials Based on Polymeric-Ammonium Cations for Stable Large-Area Solar Cell

Despite the dramatic rise in power conversion efficiencies (PCEs) of perovskite solar cells (PeSCs), concerns surrounding the long-term stability as well as the poor reproducibility in the archetypal three-dimensional (3D) perovskite, MAPbI 3 (MA = CH 3 NH 3 ), have the potential to derail commercialization. We have reported the fabrication and properties of a series of 2D perovskite compounds (PEI) 2 (MA) n −1 Pb n I 3 n +1 ( n = 3, 5, 7) by incorporating polyethylenimine (PEI) cations within the layered structure. The benefits of using intercalated polymer cations in the multilayered films are multiple: moisture resistance and film quality are greatly enhanced compared to that of their 3D MAPbI 3 analogue; charge transport within solar cells can also be improved compared to that of 2D materials using small-molecule bulky ammonium. The moisture-stable nature of the multilayered perovskite materials allow for the simple one-step fabrication of cells with an aperture area of 2.32 cm 2 under ambient humidity that have a PCE up to 8.77%. Overall, the 2D perovskite family offers rich multitudes of substituent and crystal structures, defining a promising class of stable and efficient light-absorbing materials.