Rationally designed Dion-Jacobson Tin-halide perovskites with improved phase stability and Inter-layer charge transport by intercalating alkyl cation-ligands

Currently, the development of CsSnI3 perovskite is still greatly hindered by their intrinsic deficiencies, such as their easy phase transformation. To address this issue, we theoretically constructed Dion-Jacobson (DJ) perovskites intercalated by divalent 1,5-pentamethylenediamine (PeDA2+) exhibit significantly enhanced phase stability. However, the carrier mobility is always depressed owing to the charge localization and severe lattice distortion in the presence of spacers among wafers. Thus, the alkyl ligand cations (e.g., ethylenediamine (EDA), 1,3-propanediamine (PDA), 1,4-butanediamine (BDA)) with varying lengths as organic intercalators are examined for optimizing charge transfer. Compared with the other configures, the (PDA)Cs2Sn3I10 exhibits the most significantly improved stability due to the enhanced chemical bonding and faintest structural distortions, as evidenced by computed the formation enthalpy. Formation energy and transition level of tin-vacancy defect further confirm the improved stability and depressed defect-trapping states. Meanwhile, 2D-(PDA)Cs2Sn3I10 exhibit obviously increased electrical conductivity and reduced carrier effective masses, which might benefit the photoelectric conversion of solar cells.