# Giant excitonic absorption and emission in two-dimensional group-III nitrides

## TL;DR

This paper systematically investigates excitonic absorption and emission in monolayer group-III nitrides, revealing strong excitonic effects and potential for optoelectronic applications like LEDs and solar cells.

## Contribution

It provides a comprehensive ab-initio analysis of excitonic properties in 2D BN, AlN, GaN, and InN, highlighting their strong excitonic effects and potential for optoelectronic devices.

## Key findings

- Strong excitonic effects due to low dimensionality and reduced screening.
- Exciton radiative lifetimes vary from tenths of picoseconds to tenths of nanoseconds.
- InN shows promising properties for light-emitting diodes and solar cells.

## Abstract

Absorption and emission of pristine-like semiconducting monolayers of BN, AlN, GaN, and InN are here systematically studied by ab-initio methods. We calculate the absorption spectra for in-plane and out-of-plane light polarization including quasiparticle and excitonic effects. Chemical trends with the cation of the absorption edge and the exciton binding are discussed in terms of the band structures. Exciton binding energies and localization radii are explained within the Keldysh model for excitons in two dimensions. The strong excitonic effects are due to the interplay of low dimensionality, confinement effects, and reduced screening. We find exciton radiative lifetimes ranging from tenths of picoseconds (BN) to tenths of nanoseconds (InN) at room temperature, thus making 2D nitrides, especially InN, promising materials for light-emitting diodes and high-performance solar cells.