The dielectric impact of layer distances on exciton and trion binding energies in van der Waals heterostructures

TL;DR

This paper investigates how the dielectric environment and interlayer distances in van der Waals heterostructures influence exciton and trion binding energies, combining electrostatic modeling with many-particle methods to match experimental data.

Contribution

It introduces a combined electrostatic and many-particle approach to accurately predict how layer distances affect excitonic properties in heterostructures.

Findings

Binding energies are sensitive to atomic-scale interlayer distances.

The model accurately predicts experimentally measured trion binding energies.

Spectroscopic measurements validate the theoretical predictions.

Abstract

The electronic and optical properties of monolayer transition-metal dichalcogenides (TMDs) and van der Waals heterostructures are strongly subject to their dielectric environment. In each layer the field lines of the Coulomb interaction are screened by the adjacent material, which reduces the single-particle band gap as well as exciton and trion binding energies. By combining an electrostatic model for a dielectric hetero-multi-layered environment with semiconductor many-particle methods, we demonstrate that the electronic and optical properties are sensitive to the interlayer distances on the atomic scale. Spectroscopical measurements in combination with a direct solution of a three-particle Schr\"odinger equation reveal trion binding energies that correctly predict recently measured interlayer distances.