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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.
Xu et al. (Mon,) studied this question.