Band Edge Engineering of 2D Perovskite Structures through Spacer Cation Engineering for Solar Cell Applications

Recently, Dion–Jacobson phases of 2D perovskites have emerged as potential candidates over Ruddlesden–Popper phases for solar cell applications due to their short inorganic layer contact distance. The band edge electronic structure of hybrid metal halide perovskites is mainly composed of inorganic counterparts. Exploring cationic substitution to change the nature of the conduction band edge of the perovskite can give a new direction to the 2D perovskite research. In this regard, we have designed pyrylium- and thiopyrylium-based new types of spacer cations in the Dion–Jacobson phase and shown that the perovskite conduction band edge states can be dominated by organic spacer cations as opposed to the previously reported systems. Therefore, we show here that the heterocyclic ring-based spacer cations in 2D perovskites not only assure the geometrical stability but also contribute significantly to the conduction band edge of the material.