# Rigid band shifts in two-dimensional semiconductors through environmental screening

## TL;DR

This study demonstrates that environmental dielectric screening causes primarily rigid band gap reductions in 2D WS$_2$, with minimal impact on electronic dispersion, highlighting dielectric engineering as a tool for tuning 2D semiconductor properties.

## Contribution

It provides experimental and theoretical evidence that dielectric environment induces mainly rigid band shifts in 2D semiconductors, informing future material engineering strategies.

## Key findings

- Band gap reduction due to increased dielectric screening
- Minimal change in electronic dispersion
- Guidance for dielectric engineering in 2D materials

## Abstract

We investigate the effects of environmental dielectric screening on the electronic dispersion and the band gap in the atomically-thin, quasi two-dimensional (2D) semiconductor WS$_2$ using correlative angle-resolved photoemission and optical spectroscopies, along with first-principles calculations. We find the main effect of increased environmental screening to be a reduction of the band gap, with little change to the electronic dispersion of the band structure. These essentially rigid shifts of the bands results from the special spatial structure of the changes in the Coulomb potential induced by the dielectric environment in the 2D limit. Our results suggest dielectric engineering as a non-invasive method of tailoring the band structure of 2D semiconductors and provide guidance for understanding the electronic properties of 2D materials embedded in multilayer heterostructures.