Excitonic gaps and exciton binding energies in multilayer phosphorene quantum dots

TL;DR

This paper calculates the dielectric properties and excitonic gaps of multilayer phosphorene quantum dots using DFT, showing good agreement with experimental optical gaps and emphasizing the importance of dielectric screening in 2D materials.

Contribution

It introduces a method to compute dielectric screening and excitonic properties in multilayer phosphorene quantum dots using DFT-derived polarizabilities.

Findings

Excitonic gaps match experimental optical gaps in multilayer phosphorene.

Dielectric screening significantly influences exciton binding energies.

Large quantum dots show consistent excitonic properties with measurements.

Abstract

Dielectric screening is greatly important to an accurate calculation of the exciton binding energies in two-dimensional materials. In this work, we calculate the dielectric function and 2D polarizability of multilayer (up to three) phosphorene sheets using Density Functional Theory. The 2D polarizabilities are then used in the dielectric screening of the excitonic interaction in multilayer phosphorene quantum dots. In the limit of large quantum dots, excitonic gaps are shown to exhibit very good agreement with state-of-the-art measurements of the optical gaps of multilayer phosphorene sheets deposited in different substrates.