Exciton-phonon relaxation bottleneck and radiative decay of thermal exciton reservoir in two-dimensional materials

TL;DR

This paper investigates how exciton-phonon interactions influence the radiative decay of excitons in 2D materials, revealing a temperature-dependent depletion of radiative states due to scattering limitations.

Contribution

It provides an analytical solution to the kinetic equation describing exciton distribution, highlighting the exciton-phonon scattering bottleneck in 2D materials.

Findings

Strong depletion of radiative excitons at low temperatures

Analytical kinetic model for exciton distribution

Temperature-dependent scattering effects

Abstract

We study exciton radiative decay in a two-dimensional material, taking into account large thermal population in the non-radiative states, from which excitons are scattered into the radiative states by acoustic phonons. We find an analytical solution of the kinetic equation for the non-equilibrium distribution function of excitons in the radiative states. Our estimates for bright excitons in transition metal dichalcogenides indicate a strong depletion of radiative state population due to insufficient exciton-phonon scattering rate at low temperatures.