Comparative study of the binding energy in a thin and ultra-thin organic-inorganic perovskite within dielectric mismatches effects

The multi-quantum well (MQW) organic-inorganic perovskite offer an approach of tuning the exciton binding energy based on the well-barrier dielectric mismatch effect, which called the image charge effect. The exfoliation from MQW organic-inorganic perovskite forms a twodimensional (2D) nano-sheet. As with other 2D materials, like graphene or transition metal dichalcogenides (TMDs), the ultra-thin perovskites layers are highly sensitive to the dielectric environment. We investigate the ultrathin crystalline 2D van-der-Waals (vdW) layers of organic-inorganic perovskite crystals close to a surface of the substrate. We show that binding exciton energy is strongly influenced by the surrounding dielectric environment. We find that the Keldysh model somehow estimates the strong dependence of the exciton binding energies on environmental screening. We compare our binding energies results with experimental results in the (C6H13NH3)2PbI4 perovskite, and we estimate the binding energy values of (C4H9NH3)2PbBr4.