# Quenching of exciton recombination in strained two-dimensional monochalcogenides

## TL;DR

This paper predicts that strain-induced localization in two-dimensional monochalcogenides can produce long-lived excitons with high binding energies, significantly reducing recombination rates.

## Contribution

It introduces a theoretical framework showing how local strain fields in 2D monochalcogenides create long-lived, highly bound excitons by spatially separating electrons and holes.

## Key findings

- Localized excitons have high binding energies.
- Strain fields hinder exciton recombination.
- Long-lived excitons are predicted in 2D monochalcogenides.

## Abstract

We predict that long-lived excitons with very large binding energies can also exist in a single or few layers of monochalcogenides such as GaSe. Our theoretical study shows that excitons confined by a radial local strain field are unable to recombine despite of electrons and holes co-existing in space. The localized single-particle states are calculated in the envelope function approximation based on a three-band $\boldsymbol{k}\cdot \boldsymbol{p}$ Hamiltonian obtained from DFT calculations. The binding energy and the decay rate of the exciton ground state are computed after including correlations in the basis of electron-hole pairs. The interplay between the localized strain and the caldera-type valence band, characteristic of few-layered monochalcogenides, creates localized electron and hole states with very different quantum numbers which hinders the recombination even for singlet excitons.