Theory of Neutral and Charged Excitons in Monolayer Transition Metal Dichalcogenides

TL;DR

This paper develops a microscopic effective mass theory for neutral and charged excitons in monolayer transition metal dichalcogenides, accurately predicting binding energies and providing microscopic insights validated by experiments.

Contribution

It introduces a new effective mass model parametrized by ab initio data that accurately describes excitons and trions in monolayer TMDs, including screening effects.

Findings

Calculated exciton binding energies match many-body computations.

Trion binding energies agree with recent experimental data.

Provides atomistic understanding of microscopic features affecting trion binding.

Abstract

We present a microscopic theory of neutral excitons and charged excitons (trions) in monolayers of transition metal dichalcogenides, including molybdenum disulfide. Our theory is based on an effective mass model of excitons and trions, parametrized by ab initio calculations and incorporating a proper treatment of screening in two dimensions. The calculated exciton binding energies are in good agreement with high-level many-body computations based on the Bethe-Salpeter equation. Furthermore, our calculations for the more complex trion species compare very favorably with recent experimental measurements, and provide atomistic insight into the microscopic features which determine the trion binding energy.