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

TL;DR

This study investigates how dielectric mismatches affect exciton binding energies in ultra-thin organic-inorganic perovskite layers, highlighting environmental influence and comparing theoretical estimates with experimental data.

Contribution

It provides a comparative analysis of binding energies in thin and ultra-thin perovskite layers considering dielectric effects, using the Keldysh model and experimental validation.

Findings

Binding energy strongly depends on dielectric environment.

Keldysh model effectively estimates environmental screening effects.

Experimental results align with theoretical predictions.

Abstract

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.