# Dimensionality and Anisotropicity Dependence of Radiative Recombination in Nanostructured Phosphorene

## TL;DR

This paper develops a first-principles framework to study how dimensionality and anisotropicity influence radiative recombination in nanostructured phosphorene, revealing significant effects on exciton lifetime and polarization of emitted light.

## Contribution

It introduces a general first-principles approach to analyze exciton dynamics across different dimensions in low-dimensional semiconductors, highlighting the impact of anisotropicity.

## Key findings

- Radiative lifetime increases by about 1000 times when reducing dimensionality from 2D to 0D.
- Finite temperature radiative lifetime calculations require accurate exciton dispersion models.
- Monolayer phosphorene emits linearly polarized light, unlike isotropic 2D materials.

## Abstract

The interplay between dimensionality and anisotropicity leads to intriguing optoelectronic properties and exciton dynamics in low dimensional semiconductors. In this study we use nanostructured phosphorene as a prototypical example to unfold such complex physics and develop a general first-principles framework to study exciton dynamics in low dimensional systems. Specifically we derived the radiative lifetime and light emission intensity from 2D to 0D systems based on many-body perturbation theory, and investigated the dimensionality and anisotropicity effects on radiative recombination lifetime both at 0 K and finite temperature, as well as polarization and angle dependence of emitted light. We show that the radiative lifetime at 0 K increases by an order of $10^3$ with the lowering of one dimension (i.e. from 2D to 1D nanoribbons or from 1D to 0D quantum dots). We also show that obtaining the radiative lifetime at finite temperature requires accurate exciton dispersion beyond the effective mass approximation. Finally, we demonstrate that monolayer phosphorene and its nanostructures always emit linearly polarized light consistent with experimental observations, different from in-plane isotropic 2D materials like MoS2 and h-BN that can emit light with arbitrary polarization, which may have important implications for quantum information applications.