Comparative study of the exciton binding energies of thin and ultrathin organic-inorganic perovskites due to dielectric mismatch effects

Abstract

Multi-quantum well organic-inorganic perovskites offer an approach to tunable exciton binding energies based on well-barrier dielectric mismatches, that is, the image-charge effect. As with other two-dimensional materials, ultrathin exfoliated perovskites are highly sensitive to their dielectric environments. We investigate ultrathin crystalline two-dimensional van der Waals layers of organic-inorganic perovskite crystals adjacent to the surface of a substrate. The exciton binding energies are strongly influenced by the surrounding dielectric environment. The Keldysh model describes this dependence. We compare our binding-energy results with data in the (C6H13NH3)2PbI4 perovskite and estimate binding-energy values for (C4H9NH3)2PbBr4.