First-Principles Study of Enhanced Out-of-Plane Transport Properties and Stability in Dion–Jacobson Two-Dimensional Perovskite Semiconductors for High-Performance Solar Cell Applications

Two-dimensional (2D) perovskites have attracted much attention in research for solar cell applications because of their increased stability. The versatile structures of 2D perovskites enable fine-tuning of their optoelectronic properties. Newly reported Dion-Jacobson (DJ) perovskites have shown superior out-of-plane charge transport properties and better stability than the Ruddlesden-Popper (RP)-type perovskites because of their freedom from weak van der Waals interactions between adjacent layers. Tunable band gaps of 2D AMX₄ can be achieved by alternatively substituting the corresponding compositions at A, M, and X sites, and significantly enhanced stability is observed because of the two hydrogen bonds formed at both ends of the divalent organic cation. Enhanced interlayer charge transport properties are found in DJ perovskites because of the short apical I-I distance in AMX₄ perovskites, especially for PDAPbI₄ and PDASnI₄ perovskites. These findings provide us effective ways to tune the stability and optoelectronic properties of 2D perovskites.